ALBERT

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Recent observations and modeling increasingly reveal the key role of cold pools in organizing the convective cloud field. Several methods for detecting cold pools in simulations exist, but are usually based on buoyancy fields and fall short of reliably identifying the active gust front. The current cold pool (CP) detection and tracking algorithm (CoolDeTA), aims to identify cold pools and follow them in time, thereby distinguishing their active gust fronts and the “offspring” rain cells generated nearby. To accomplish these tasks, CoolDeTA utilizes a combination of thermodynamic and dynamical variables and examines the spatial and temporal relationships between cold pools and rain events. We demonstrate that CoolDeTA can reconstruct CP family trees. Using CoolDeTA we can contrast radiative convective equilibrium (RCE) and diurnal cycle CP dynamics, as well as cases with vertical wind shear and without. We show that the results obtained are consistent with a conceptual model where CP triggering of children rain cells follows a simple birth rate, proportional to a CP's gust front length. The proportionality factor depends on the ambient atmospheric stability and is lower for RCE, in line with marginal stability as traditionally ascribed to the moist adiabat. In the diurnal case, where ambient stability is lower, the birth rate thus becomes substantially higher, in line with periodic insolation forcing—resulting in essentially run‐away mesoscale excitations generated by a single parent rain cell and its CP.〈/p〉

Beschreibung: Plain Language Summary: Cold pools are cooled air masses below thunderstorm clouds, produced when rain evaporates underneath such clouds. Cold pools are important, as they produce strong gusts and have been associated with clumping of rain cells, whereby heavy rainfall over relatively small areas could be generated—with implications for flooding. The current work describes a method that helps identify such cold pools in computer simulation data. In contrast to earlier methods, we here show that the interaction between a CP and its surroundings can be reconstructed by the method. We show that this identification works under a range of contexts, such as when horizontal wind is applied in the simulations or when the surface temperature is not constant—as might often be the case over a land surface. The identification reveals interesting dynamical effects, such as that in some cases, cold pools can kick‐start a form of chain reaction, by which “rain cell children” of it give rise to additional cold pools that again produce children, and so forth. The dynamics revealed is in line with expectations of widespread, so‐called mesoscale convective systems over land, whereas over an ocean surface the dynamics is much less explosive.〈/p〉

Beschreibung: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Our CoolDeTA algorithm reliably detects and tracks cold pools and their causal chains〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉We propose a simple conceptual model which reproduces the cascade‐like mesoscale cold pool dynamics identified by CoolDeTA〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉CoolDeTA opens for new studies into the dynamics of convective self‐organization through cold pools〈/p〉〈/list-item〉 〈/list〉 〈/p〉

Beschreibung: Villum Fonden http://dx.doi.org/10.13039/100008398

Beschreibung: European Research Council http://dx.doi.org/10.13039/501100000781

Beschreibung: Novo Nordisk Foundation Interdisciplinary Synergy Program

Beschreibung: Scientific Steering Committee

Beschreibung: https://doi.org/10.5281/zenodo.6513224

Beschreibung: https://github.com/Shakiro7/coldPool-detection-and-tracking

Beschreibung: https://doi.org/10.5281/zenodo.10115957

Beschreibung: https://doi.org/10.7717/peerj.453

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Dansgaard‐Oeschger (D‐O) climate variability during the last glaciation was first evidenced in ice cores and marine sediments, and is also recorded in various terrestrial paleoclimate archives in Europe. The relative synchronicity across Greenland, the North Atlantic and Europe implies a tight and fast coupling between those regions, most probably effectuated by an atmospheric transmission mechanism. In this study, we investigated the atmospheric changes during Greenland interstadial (GI) and stadial (GS) phases based on regional climate model simulations using two specific periods, GI‐10 and GS‐9 both around 40 ka, as boundary conditions. Our simulations accurately capture the changes in temperature and precipitation as reconstructed by the available proxy data. Moreover, the simulations depict an intensified and southward shifted eddy‐driven jet during the stadial period. Ultimately, this affects the near‐surface circulation toward more southwesterly and cyclonic flow in western Europe during the stadial period, explaining much of the seasonal climate variability recorded by the proxy data, including oxygen isotopes, at the considered proxy sites.〈/p〉

Beschreibung: Plain Language Summary: The climate during the last ice age varied between colder and warmer periods on timescales ranging from hundreds to thousands of years. This variability was first detected in Greenland ice cores and marine sediment cores of the North Atlantic, as well as in continental geological records in Europe. The variation between the colder and warmer periods occur mostly simultaneously in Greenland and in Europe, which is why the atmosphere is assumed to have an important role in transferring the climate signals. We simulated two different periods of the last ice age, one colder and one warmer around 40,000 years ago, using a regional climate model. The aim was to study how the climate and atmospheric circulation changed during these two periods. We find the eddy‐driven jet over the North Atlantic intensified and shifted southward during the colder period. The jet influences the near‐surface atmospheric circulation and leads to more southwesterly and cyclonic flow in western Europe. Oxygen isotope variations observed in western European paleoclimate records may be partly explained by different, more southern moisture sources on top of changes in seasonal temperatures.〈/p〉

Beschreibung: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Simulated temperatures agree with proxy data; precipitation is biased but GI‐10 versus GS‐9 differences are well captured〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The stadial winter jet stream is intensified and shifted southward, consistent with dominant southwesterly/cyclonic flow in western Europe〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Oxygen isotope signal changes at western European proxy sites may be explained not only by temperature but also by varying moisture sources〈/p〉〈/list-item〉 〈/list〉 〈/p〉

Beschreibung: NRDIO

Beschreibung: AXA Research Fund http://dx.doi.org/10.13039/501100001961

Beschreibung: https://doi.org/10.5065/1dfh-6p97

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Unlike actual rainfall, the spatial extent of rainfall maps is often determined by administrative and political boundaries. Similarly, data from commercial microwave links (CMLs) is usually acquired on a national basis and exchange among countries is limited. Up to now, this has prohibited the generation of transboundary CML‐based rainfall maps despite the great extension of networks across the world. We present CML based transboundary rainfall maps for the first time, using independent CML data sets from Germany and the Czech Republic. We show that straightforward algorithms used for quality control strongly reduce anomalies in the results. We find that, after quality control, CML‐based rainfall maps can be generated via joint and consistent processing, and that these maps allow to seamlessly visualize rainfall events traversing the German‐Czech border. This demonstrates that quality control represents a crucial step for large‐scale (e.g., continental) CML‐based rainfall estimation.〈/p〉

Beschreibung: Plain Language Summary: Rainfall maps are usually based on gauge observations on the ground or radar. They are crucial for predicting or reconstructing flooding events. Commercial microwave links are special kinds of rainfall sensors. Their actual purpose is the signal propagation within a cellular network. However, since the signal is attenuated when it rains, they can also be exploited for rainfall estimation. To estimate rainfall from the observed attenuation requires careful data processing. Algorithms for that are usually adjusted to national data sets with their specific characteristics. In this study, we use, for the first time, two independent data sets of commercial microwave links (from Germany and the Czech Republic) with the aim of generating transboundary rainfall maps. As the data sets vary in many respects, several algorithms need to be adjusted and extended to allow processing them consistently. We show that it is possible to create meaningful rainfall maps of rain events that traverse the border between Germany and the Czech Republic. This can be considered a major step toward seamless rainfall maps on even larger, that is, continental scale.〈/p〉

Beschreibung: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Transboundary rainfall maps based on independent networks of commercial microwave links (CMLs) are generated for the first time〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉German and Czech data sets of CMLs differ significantly with respect to network characteristics〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Quality control is important for heterogeneous data of CMLs〈/p〉〈/list-item〉 〈/list〉 〈/p〉

Beschreibung: German Research Foundation

Beschreibung: Czech Science Foundation

Beschreibung: https://doi.org/10.5281/zenodo.4810169

Beschreibung: https://doi.org/10.5281/zenodo.7973736

Beschreibung: https://opendata.dwd.de/climate_environment/CDC

Beschreibung: An important aspect of rainfall estimation is to accurately capture extreme events. Commercial microwave links (CMLs) can complement weather radar and rain gauge data by estimating path‐averaged rainfall intensities near ground. Our aim with this paper was to investigate attenuation induced complete loss of signal (blackout) in the CML data. This effect can occur during heavy rain events and leads to missing extreme values. We analyzed 3 years of attenuation data from 4,000 CMLs in Germany and compared it to a weather radar derived attenuation climatology covering 20 years. We observed that the average CML experiences 8.5 times more blackouts than we would have expected from the radar derived climatology. Blackouts did occur more often for longer CMLs (e.g., 〉10 km) despite their increased dynamic range. Therefore, both the hydrometeorological community and network providers can consider our analysis to develop mitigation measures.

Beschreibung: Plain Language Summary: Commercial microwave links (CMLs) are used to transmit information between towers of cellphone networks. If there is rainfall along the transmission path, the signal level is attenuated. By comparing the transmitted and received signal levels, the average rainfall intensity along the path can be estimated. If the attenuation is too strong, no signal is received, no information can be transmitted and no rainfall estimate is available. This is unfavorable both for network stability and rainfall estimation. In this study, we investigated the frequency of such blackouts in Germany. How many blackouts per year are observed in a 3 year CML data set covering around 4,000 link paths and how many are expected from 20 years of weather radar data? We observed that the average CML experiences 8.5 times more blackouts than we would have expected from the radar derived climatology. Blackouts did occur more often for long CMLs, which was an unexpected finding. While only one percent of the annual rainfall amount is missed during blackouts, the probability that a blackout occurs was very high for high rain rates. Both, the hydrometeorological community and network providers can consider our analysis to develop mitigation measures.

Beschreibung: Key Points: Complete loss of commercial microwave link (CML) signals during heavy rain leads to missing rainfall extremes. Magnitude of observed blackouts exceeds climatologically expected values. Unexpectedly, longer CMLs experience more blackouts.

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: Helmholtz Association http://dx.doi.org/10.13039/501100009318

Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347

Beschreibung: Karlsruhe Institute of Technology http://dx.doi.org/10.13039/100009133

Beschreibung: https://doi.org/10.5281/zenodo.7245440

Beschreibung: https://github.com/pycomlink/pycomlink/blob/12fc302539851b19f7656cf7e2438c0ddbaa48bf/notebooks/Blackout%20gap%20detection%20examples.ipynb

Beschreibung: https://doi.org/10.5281/zenodo.6337557

Beschreibung: https://doi.org/10.5676/DWD/RADKLIM_YW_V2017.002

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉In 2022, western Europe experienced its hottest summer on record and widespread dry conditions, with substantial impacts on health, water and vegetation. We use a reanalysis to classify daily mean sea level pressure fields and to investigate the influence of synoptic circulations on the occurrence of temperature extremes and dry days. Summer 2022 featured an above‐normal occurrence of anticyclones extending from the British Isles to the Baltic countries, as well as enhanced easterly, southerly and low‐flow conditions which contributed to the observed extremes over southern and western Europe. While the hot summer of 2022 is only partially explained by circulation anomalies, such anomalies played a key role in the exceptional occurrence of dry days. The comparison with summer circulation anomalies projected by twenty global climate models moreover suggests that future circulation changes will further exacerbate hot and dry extremes over Europe.〈/p〉

Beschreibung: Plain Language Summary: In 2022, western Europe recorded its hottest summer up to date since preindustrial times. At the same time, widespread dry conditions caused dramatic impacts on human health, water resources, crop yields and wildfires. This was partly enhanced by the human–caused cumulative emissions of greenhouse gases, but also potentially by large‐scale circulation anomalies that may also be triggered by global warming. By grouping distinct weather patterns, we find that many extreme hot days during the summer of 2022 over well‐defined parts of Europe were favored by anomalous transport of hot and dry air masses or persistent low‐wind conditions. These weather patterns were essential but not the dominant factor that led to the occurrence of extreme temperatures. Yet, they played a key role in enhancing the number of dry days. We also find that the weather patterns observed in summer 2022 will become more common in coming decades if greenhouse gas emissions remain without reduction. This would further worsen hot and dry extremes in summer over Europe.〈/p〉

Beschreibung: Key Points : 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉European summer 2022 hot extremes have been enhanced by an anomalous occurrence of distinct circulation types over different subdomains〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Predominant circulation anomalies also contributed to the exceptional number of dry days, as much as local, mostly thermodynamical effects〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Such anomalous circulations will become more common, thus further worsening European hot and dry extremes〈/p〉〈/list-item〉 〈/list〉 〈/p〉

Beschreibung: HORIZON EUROPE Marie Sklodowska‐Curie Actions http://dx.doi.org/10.13039/100018694

Beschreibung: https://doi.org/10.24381/cds.adbb2d47

Beschreibung: https://doi.org/10.5194/gmd-9-1937-2016

Beschreibung: In this study, we investigate whether a better representation of precipitation in the Amazon basin arises through an explicit representation of convection and whether it is related to the representation of organized systems. In addition to satellite data, we use ensemble simulations of the ICON‐NWP model at storm‐resolving (2.5–5.0 km) scales with explicit convection (E‐CON) and coarse resolutions, with parameterized convection (P‐CON). The main improvements in the representation of Amazon precipitation by E‐CON are in the distribution of precipitation intensity and the spatial distribution in the diurnal cycle. By isolating precipitation from organized convective systems (OCS), it is shown that many of the well simulated precipitation features in the Amazon arise from the distribution of these systems. The simulated and observed OCS are classified into 6 clusters which distinguish nocturnal and diurnal OCS. While the E‐CON ensembles capture the OCS, especially their diurnal cycle, their frequency is reduced compared to observations. Diurnal clusters are influenced by surface processes such as cold pools, which aid to the propagation of OCS. Nocturnal clusters are rather associated with strong low‐level easterlies, possibly related to the Amazonian low‐level jet. Our results also show no systematic improvement with a twofold grid refinement and remaining biases related to stratiform features of OCS suggest that yet unresolved processes play an important role for correctly representing precipitating systems in the Amazon.

Beschreibung: Plain Language Summary: The Amazon basin is a relevant element of the Earth system because it influences the global water and carbon cycle, as well as it constitutes a unique ecosystem. Over this important region, conventional climate models do not simulate basic features of rainfall given their inability to resolve this physical process due to their coarse spatial resolution. In this study, we use high‐resolution simulations that allow an explicit representation of such physical process (moist convection) and compare them with a set of coarse‐resolution simulations and observed precipitation. We find that improvements in the representation of Amazon rainfall, such as the distribution of light and high intensity rain rates, as well as the spatial variability of the diurnal cycle, are explained by the explicit representation of moist convection. Moreover, these improvements arise from the representation of big and organized systems that produce intense rainfall (OCS). We find that particular environmental conditions are associated with the OCS according to their time of occurrence. Diurnal OCS are mainly influenced by interactions with the surface, while nocturnal OCS are related to strong low‐level winds. Some of the remaining discrepancies with observed OCS do not show improvements when refining the grid by a factor of two.

Beschreibung: Key Points: An explicit representation of convection enables the emergence of organized systems (OCS) leading to improved simulations of Amazon rainfall. Propagating cold‐pools and strong low‐level easterlies are related to the occurrence of diurnal and nocturnal OCS, respectively. Systematic biases in the size, intensity and nocturnal precipitation phase of OCS are insensitive to a twofold refinement in resolution.

Beschreibung: Max Planck Society for the Advancement of Science

Beschreibung: European Horizon 2020 project CONSTRAIN

Beschreibung: https://www.metoffice.gov.uk/hadobs/hadisst/data/download.html

Beschreibung: https://www.ncei.noaa.gov/data/cmorph-high-resolution-global-precipitation-estimates/access/30min/8km

Beschreibung: https://www.hydrosheds.org/products/hydrobasins

Beschreibung: https://esgf-data.dkrz.de/projects/cmip6-dkrz/

Beschreibung: https://pure.mpg.de/

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉We monitored stable water isotopes in liquid precipitation and atmospheric water vapour (δ〈sub〉v〈/sub〉) using in situ cavity ring‐down spectroscopy (CRDS) over a 2 month period in an urban green space area in Berlin, Germany. Our aim was to better understand the origins of atmospheric moisture and its link to water partitioning under contrasting urban vegetation. δ〈sub〉v〈/sub〉 was monitored at multiple heights (0.15, 2 and 10 m) in grassland and forest plots. The isotopic composition of δ〈sub〉v〈/sub〉 above both land uses was highly dynamic and positively correlated with that of rainfall indicating the changing sources of atmospheric moisture. Further, the isotopic composition of δ〈sub〉v〈/sub〉 was similar across most heights of the 10 m profiles and between the two plots indicating high aerodynamic mixing. Only at the surface at ~0.15 m height above the grassland δ〈sub〉v〈/sub〉 showed significant differences, with more enrichment in heavy isotopes indicative of evaporative fractionation especially after rainfall events. Further, disequilibrium between δ〈sub〉v〈/sub〉 and precipitation composition was evident during and right after rainfall events with more positive values (i.e., values of vapour higher than precipitation) in summer and negative values in winter, which probably results from higher evapotranspiration and more convective precipitation events in summer. Our work showed that it is technically feasible to produce continuous, longer‐term data on δ〈sub〉v〈/sub〉 isotope composition in urban areas from in situ monitoring using CRDS, providing new insights into water cycling and partitioning across the critical zone of an urban green space in Central Europe. Such data have the potential to better constrain the isotopic interface between the atmosphere and the land surface and to thus, improve ecohydrological models that can resolve evapotranspiration fluxes.〈/p〉

Beschreibung: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉In situ measurements of urban atmospheric water isotopes (δ〈sub〉v〈/sub〉) at different heights produce reliable and stable high‐resolution data. Urban atmospheric vapour is influenced by varying drivers depending on the type of green space. δ〈sub〉v〈/sub〉 above grassland and tree stands was similar at 10 m height, but near‐surface δ〈sub〉v〈/sub〉 indicated higher evaporation and vapour enrichment over grass. We detected occasional dis‐equilibrium between vapour and precipitation isotopes.〈boxed-text position="anchor" content-type="graphic" id="hyp14989-blkfxd-0001" xml:lang="en"〉 〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:08856087:media:hyp14989:hyp14989-toc-0001"〉 〈/graphic〉 〈/boxed-text〉〈/p〉

Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: Einstein Stiftung Berlin http://dx.doi.org/10.13039/501100006188

Beschreibung: Leverhulme Trust http://dx.doi.org/10.13039/501100000275

Beschreibung: German Research Foundation http://dx.doi.org/10.13039/501100001659

Beschreibung: Einstein Research Unit

Beschreibung: Einstein Foundation Berlin and Berlin University Alliance

Beschreibung: BiNatur

Beschreibung: BMBF http://dx.doi.org/10.13039/501100002347

Beschreibung: Leverhulme Trust through the ISO‐LAND project

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Many operational weather services use ensembles of forecasts to generate probabilistic predictions. Computational costs generally limit the size of the ensemble to fewer than 100 members, although the large number of degrees of freedom in the forecast model would suggest that a vastly larger ensemble would be required to represent the forecast probability distribution accurately. In this study, we use a computationally efficient idealised model that replicates key properties of the dynamics and statistics of cumulus convection to identify how the sampling uncertainty of statistical quantities converges with ensemble size. Convergence is quantified by computing the width of the 95% confidence interval of the sampling distribution of random variables, using bootstrapping on the ensemble distributions at individual time and grid points. Using ensemble sizes of up to 100,000 members, it was found that for all computed distribution properties, including mean, variance, skew, kurtosis, and several quantiles, the sampling uncertainty scaled as 〈mml:math id="jats-math-1" display="inline" overflow="scroll"〉〈mml:msup〉〈mml:mrow〉〈mml:mi〉n〈/mml:mi〉〈/mml:mrow〉〈mml:mrow〉〈mml:mo form="prefix"〉−〈/mml:mo〉〈mml:mn〉1〈/mml:mn〉〈mml:mo stretchy="false"〉/〈/mml:mo〉〈mml:mn〉2〈/mml:mn〉〈/mml:mrow〉〈/mml:msup〉〈/mml:math〉 for sufficiently large ensemble size 〈mml:math id="jats-math-2" display="inline" overflow="scroll"〉〈mml:mrow〉〈mml:mi〉n〈/mml:mi〉〈/mml:mrow〉〈/mml:math〉. This behaviour is expected from the Central Limit Theorem, which further predicts that the magnitude of the uncertainty depends on the distribution shape, with a large uncertainty for statistics that depend on rare events. This prediction was also confirmed, with the additional observation that such statistics also required larger ensemble sizes before entering the asymptotic regime. By considering two methods for evaluating asymptotic behaviour in small ensembles, we show that the large‐〈mml:math id="jats-math-3" display="inline" overflow="scroll"〉〈mml:mrow〉〈mml:mi〉n〈/mml:mi〉〈/mml:mrow〉〈/mml:math〉 theory can be applied usefully for some forecast quantities even for the ensemble sizes in operational use today.〈/p〉

Beschreibung: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉An idealised ensemble that replicates key properties of the dynamics and statistics of cumulus convection is used to identify how sampling uncertainty of statistical quantities converges with ensemble size. A universal asymptotic scaling for this convergence was found, which was dependent on the statistic and the distribution shape, with largest uncertainty for statistics that depend on rare events. This is demonstrated in the figure below for a Gaussian distributed model variable, where the sampling uncertainty (y‐axis) for 5 quantiles (red lines) indicates that after a certain ensemble size, it begins converging asymptotically (grey lines), and the more extreme the quantile, the more members it requires for this to be the case. 〈boxed-text position="anchor" id="qj4410-blkfxd-0001" content-type="graphic" xml:lang="en"〉〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:00359009:media:qj4410:qj4410-toc-0001"〉

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: Klaus Tschira Stiftung http://dx.doi.org/10.13039/501100007316

Beschreibung: One important component of precipitating convection is the formation of convective downdrafts. They can terminate the initial updraft, affect the mean properties of the boundary layer, and cause strong winds at the surface. While the basic forcing mechanisms for downdrafts are well understood, it is difficult to formulate general relationships between updrafts, environmental conditions, and downdrafts. To better understand what controls different downdraft properties, we analyze downdrafts over tropical oceans in a global storm resolving simulation. Using a global model allows us to examine a large number of downdrafts under naturally varying environmental conditions. We analyze the various factors affecting downdrafts using three alternative methods. First, hierarchical clustering is used to examine the correlation between different downdraft, updraft, and environmental variables. Then, either random forests or multiple linear regression are used to estimate the relationships between downdraft properties and the updraft and environmental predictors. We find that these approaches yield similar results. Around 75% of the variability in downdraft mass flux and 37% of the variability in downdraft velocity are predictable. Analyzing the relative importance of our various predictors, we find that downdrafts are coupled to updrafts via the precipitation generation argument. In particular, updraft properties determine rain amount and rate, which then largely control the downdraft mass flux and, albeit to a lesser extent, the downdraft velocity. Among the environmental variables considered, only lapse rate is a valuable predictor: a more unstable environment favors a higher downdraft mass flux and a higher downdraft velocity.

Beschreibung: Plain Language Summary: Once a cloud begins to rain, the air inside or below the cloud can gain negative buoyancy and sink to the ground. This downward movement of air is called a downdraft. Downdrafts can end the life cycle of a cloud and also result in strong, sometimes destructive, wind gusts at the surface. The basic driving forces for downdrafts are well understood. For example, we know that evaporation of rain and the associated latent cooling of air is usually critical in causing the air to become negatively buoyant. Even though the basic driving forces are known, many interrelated processes contribute simultaneously to the strength of the downdraft, making it difficult to predict the strength of a downdraft under specific conditions. In this study, we use an atmospheric simulation whose model domain spans the globe and can explicitly resolve rain clouds. Compared to previous studies, the use of a global domain allows us to study a very large number of rain clouds, and their associated downdrafts, which form under very different, naturally varying environmental conditions. Machine learning techniques and traditional statistical methods agree on the result that the strength of the downdraft can be well predicted if we know the strength of the updraft that caused the downdraft or, even better, if we know the amount of rain that an updraft produced. Surprisingly, we have found that downdrafts can be predicted only slightly better if we also know other environmental conditions of the air surrounding the downdraft, such as the temperature and/or humidity profiles.

Beschreibung: Key Points: The best predictors of downdraft mass flux and velocity are rain amount and rate, respectively. Updraft properties impact downdraft properties through their control on rain formation. For a given rain amount and rate, environmental conditions add little skill to downdraft prediction.

Beschreibung: Max Planck Institute for Meteorology

Beschreibung: ARC Centre of Excellence for Climate Extremes

Beschreibung: https://mpimet.mpg.de/en/science/modeling-with-icon/code-availability

Beschreibung: http://hdl.handle.net/21.11116/0000-0009-A854-B

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉〈italic toggle="no"〉Aeolus〈/italic〉 is the first satellite mission to acquire vertical profiles of horizontal line‐of‐sight winds globally and thus fills an important gap in the Global Observing System, most notably in the Tropics. This study explores the impact of this dataset on analyses and forecasts from the European Centre for Medium‐Range Weather Forecasts (ECMWF) and Deutscher Wetterdienst (DWD), focusing specifically on the West African Monsoon (WAM) circulation during the boreal summers of 2019 and 2020. The WAM is notoriously challenging to forecast and is characterized by prominent and robust large‐scale circulation features such as the African Easterly Jet North (AEJ‐North) and Tropical Easterly Jet (TEJ). Assimilating 〈italic toggle="no"〉Aeolus〈/italic〉 generally improves the prediction of zonal winds in both forecasting systems, especially for lead times above 24 h. These improvements are related to systematic differences in the representation of the two jets, with the AEJ‐North weakened at its southern flank in the western Sahel in the ECMWF analysis, while no obvious systematic differences are seen in the DWD analysis. In addition, the TEJ core is weakened in the ECMWF analysis and strengthened on its southern edge in the DWD analysis. The regions where the influence of 〈italic toggle="no"〉Aeolus〈/italic〉 on the analysis is greatest correspond to the Intertropical Convergence Zone (ITCZ) region for ECMWF and generally the upper troposphere for DWD. In addition, we show the presence of an altitude‐ and orbit‐dependent bias in the Rayleigh‐clear channel, which causes the zonal winds to speed up and slow down diurnally. Applying a temperature‐dependent bias correction to this channel contributes to a more accurate representation of the diurnal cycle and improved prediction of the WAM winds. These improvements are encouraging for future investigations of the influence of 〈italic toggle="no"〉Aeolus〈/italic〉 data on African Easterly Waves and associated Mesoscale Convective Systems.〈/p〉

Beschreibung: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Forecasting in tropical Africa is hampered by large model errors and low availability of conventional observations. The assimilation of 〈italic〉Aeolus〈/italic〉 wind data into the operational ECMWF system leads to a consistent root‐mean‐square error (RMSE) reduction of the order of 2% in +48 h zonal wind forecasts over the region during boreal summer 2019, including the African and Tropical Easterly Jets (AEJ, TEJ) and subtropical jets (STJ). 〈boxed-text position="anchor" id="qj4442-blkfxd-0001" content-type="graphic" xml:lang="en"〉〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:00359009:media:qj4442:qj4442-toc-0001"〉 〈/graphic〉 〈/boxed-text〉〈/p〉

Beschreibung: https://aeolus-ds.eo.esa.int/oads/access/collection

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Owing to the complicated spatial–temporal characteristics of East Asian precipitation (EAP), climate models have limited skills in simulating the modern Asian climate. This consequently leads to large uncertainties in simulations of the past EAP variation and future projections. Here, we explore the performance of the newly developed Alfred Wegener Institute Climate Model, version 3 (AWI‐CM3) in simulating the climatological summer EAP. To test whether the model's skill depends on its atmosphere resolution, we design two AWI‐CM3 simulations with different horizontal resolutions. The result shows that both simulations have acceptable performance in simulating the summer mean EAP, generally better than the majority of individual models participating in the Coupled Model Intercomparison Project (CMIP6). However, for the monthly EAP from June to August, AWI‐CM3 exhibits a decayed skill, which is due to the subseasonal movement of the western Pacific subtropical high bias. The higher‐resolution AWI‐CM3 simulation shows an overall improvement relative to the one performed at a relatively lower resolution in all aspects taken into account regarding the EAP. We conclude that AWI‐CM3 is a suitable tool for exploring the EAP for the observational period. Having verified the model's skill for modern climate, we suggest employing the AWI‐CM3, especially with high atmosphere resolution, both for applications in paleoclimate studies and future projections.〈/p〉

Beschreibung: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉This figure shows the skill scores of AWI‐CM3 and CMIP6 models in simulating the climatological summer East Asian precipitation (EAP), which indicates that AWI‐CM3 simulations perform better than most CMIP6 individual models for the summer mean EAP, while AWI‐CM3's skills decay from June to August.〈boxed-text position="anchor" content-type="graphic" id="joc8075-blkfxd-0001" xml:lang="en"〉 〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:08998418:media:joc8075:joc8075-toc-0001"〉 〈alt-text〉image〈/alt-text〉 〈/graphic〉 〈/boxed-text〉〈/p〉

Beschreibung: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: Helmholtz Climate Initiative REKLIM

Beschreibung: Helmholtz Program

Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347

Beschreibung: China Scholarship Council http://dx.doi.org/10.13039/501100004543

Beschreibung: https://opendata.dwd.de/climate_environment/GPCC/html/fulldata-monthly_v2022_doi_download.html

Beschreibung: https://crudata.uea.ac.uk/cru/data/hrg/cru_ts_4.05

Beschreibung: http://aphrodite.st.hirosaki-u.ac.jp/products.html

Beschreibung: https://jra.kishou.go.jp/JRA-55/index_en.html

Beschreibung: https://esgf-node.llnl.gov/search/cmip6

Beschreibung: This study investigates the impact of increased global warming on heat stress changes and the potential number of people exposed to heat risks over Africa. For this purpose a heat index has been computed based on an ensemble‐mean of high‐resolution regional climate model simulations from the Coordinated Output for Regional Evaluations embedded in the COordinated Regional Climate Downscaling EXperiment, under two Representative Concentration Pathways (RCPs) scenarios (RCP2.6 and RCP8.5), combined with projections of population growth developed based on the Shared Socioeconomic Pathways (SSPs) scenarios (SSP1 and SSP5). Results show that by the late 21st century, the increased global warming is expected to induce a 12‐fold increase in the area extent affected by heat stress of high‐risk level. This would result in an increase of about 10%–30% in the number of days with high‐risk heat conditions, as well as about 6%–20% in their magnitude throughout the seasonal cycle over West, Central, and North‐East Africa. Therefore, and because of the lack of adaptation and mitigation policies, the exacerbation of ambient heat conditions could contribute to the exposure of about 2–8.5 million person‐events to heat stress of high‐risk level over Burkina Faso, Ghana, Niger, and Nigeria. Furthermore, it was found that the interaction effect between the climate change and population growth seems to be the most dominant in explaining the total changes in exposure due to moderate and high heat‐related risks over all subregions of the African continent.

Beschreibung: Plain Language Summary: This study investigates the impact of increased global warming on heat stress changes and the potential number of persons likely to be exposed to heat risks over Africa. Results show that by the end of the 21st century, the increased global warming is expected to induce a 12‐fold increase in the total area affected by dangerous heat conditions over the continent. This would result in an increase of about 10%–30% in the number of days with these heat conditions, as well as about 6%–20% in their magnitude throughout the seasonal cycle over West, Central and North‐East Africa. Therefore, because of the lack of adaptation and mitigation policies, the exacerbation of ambient heat conditions could contribute to the exposure of about 2–8.5 million person‐events to heat stress of high‐risk level over Burkina Faso, Ghana, Niger, and Nigeria. Since these heat events would be partly driven by interactions effects between climate change and population growth, efficient measures allowing not only to mitigate the increased greenhouse gas emissions, but also the effects of high heat on the human body must be urgently implemented on the affected countries' scale, in order to significantly decrease the vulnerability of their populations to potential heat‐related health problems.

Beschreibung: Key Points: Increased global warming induces more spatially and temporally widespread extreme heat events over West, Central and North‐East Africa. Populations of some West African countries are projected to be particularly exposed to moderate and high heat conditions. Change in population exposure to dangerous heat categories is mainly driven by the interaction effect between climate and population growth.

Beschreibung: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655

Beschreibung: Projekt DEAL

Beschreibung: https://esg-dn1.nsc.liu.se/search/cordex/

Beschreibung: https://esgf-data.dkrz.de/projects/esgf-dkrz/

Beschreibung: https://www.isimip.org/gettingstarted/details/31

Beschreibung: https://sedac.ciesin.columbia.edu/data/set/popdynamics-1-8th-pop-base-year-projection-ssp-2000-2100-rev01/data-download

Beschreibung: https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels?tab=form

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉In this study, a new multilayer urban canopy parameterization for high‐resolution (∼1 km) atmospheric models using the nudging approach to represent the impacts of urban canopies on airflow is presented. In our parameterization, a nudging term is added to the momentum equations and a source term to the turbulent kinetic energy equation to account for building effects. The challenge of this parameterization lies in defining appropriate values for the nudging coefficient and the weighting function used to reflect canopy effects. Values of both are derived and the parameterization developed is implemented and tested for idealized cases in the Mesoscale Transport and Stream model (METRAS). Comparison data are taken from obstacle‐resolving microscale model results. Results show that the parameterization using the nudging approach can simulate aerodynamic effects induced within the canopy by obstacles well, in terms of reduction of wind speeds and production of additional turbulent kinetic energy. Thus, models with existing nudging can use this approach as an efficient and effective method to parameterize dynamic urban canopy effects.〈/p〉

Beschreibung: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉In this study, a new multilayer urban canopy parameterization for high‐resolution (∼1 km) atmospheric models using the nudging approach to represent the impacts of urban canopies on airflow is presented. Results show that the parameterization developed can simulate aerodynamic effects induced within the canopy by obstacles well, in terms of reduction of wind speeds and production of additional turbulent kinetic energy. Models with existing nudging can use this approach as an efficient and effective method to parameterize dynamic urban canopy effects. 〈boxed-text position="anchor" id="qj4524-blkfxd-0001" content-type="graphic" xml:lang="en"〉〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:00359009:media:qj4524:qj4524-toc-0001"〉 〈/graphic〉 〈/boxed-text〉〈/p〉

Beschreibung: Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy‐EXC 2037 'CLICCS‐Climate, Climatic Change, and Society'

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Projected changes in summer precipitation deficits partly depend on alterations in synoptic circulations. Here, the automated Jenkinson–Collison classification is used to assess the ability of 21 global climate models (GCMs) to capture the frequency of recurring circulation types (CTs) and their implications for European daily precipitation amounts in summer (JJA). The ability of the GCMs to reproduce the observed present‐day climate features is evaluated first. Most GCMs capture the observed links between the mean CTs directional flow characteristics and the occurrence of dry days and related dry months. The most robust relationships are found for anticyclonic and easterly CTs which are generally associated with higher‐than‐average occurrences of dry conditions. Future changes in summer CTs' frequencies are estimated in the high‐emission SSP5‐8.5 scenario for the sake of a high signal‐to‐noise ratio. Our results reveal consistent changes, mainly in the zonal CTs. A robust decrease in frequency of the westerlies and an increase in the frequency of easterly CTs favour more continental, dry and warm air masses over central Europe. These dynamical changes are shown to enhance the projected summer drying over central and southern Europe.〈/p〉

Beschreibung: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Summer large‐scale circulations are derived over Europe using an automated classification. Spatial characteristics of the patterns and their influence on dry days are investigated. Future changes are explored based on global climate models. The predicted drier summers in Europe are found to be influenced by consistent changes in west‐easterly circulations.〈boxed-text position="anchor" content-type="graphic" id="joc8033-blkfxd-0001" xml:lang="en"〉 〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:08998418:media:joc8033:joc8033-toc-0001"〉 〈/graphic〉 〈/boxed-text〉〈/p〉

Beschreibung: EU International Training Network (ITN) Climate Advanced Forecasting of sub‐seasonal Extremes (CAFE)

Beschreibung: H2020 Marie Skłodowska‐Curie Actions

Beschreibung: https://github.com/PedroLormendez/jcclass

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The prediction skill of sub‐seasonal forecast models is evaluated for seven year‐round weather regimes in the Atlantic–European region. Reforecasts based on models from three prediction centers are considered and verified against weather regimes obtained from ERA‐Interim reanalysis. Results show that predicting weather regimes as a proxy for the large‐scale circulation outperforms the prediction of raw geopotential height. Greenland blocking tends to have the longest year‐round skill horizon for all three models, especially in winter. On the other hand, the skill is lowest for the European blocking regime for all three models, followed by the Scandinavian blocking regime. Furthermore, all models struggle to forecast flow situations that cannot be assigned to a weather regime (so‐called no regime), in comparison with weather regimes. Related to this, variability in the occurrence of no regime, which is most frequent in the transition seasons, partly explains the predictability gap between transition seasons and winter and summer. We also show that models have difficulties in discriminating between related regimes. This can lead to misassignments in the predicted regime during flow situations in which related regimes manifest. Finally, we document the changes in skill between model versions, showing important improvements for the ECMWF and NCEP models. This study is the first multi‐model assessment of year‐round weather regimes in the Atlantic–European domain. It advances our understanding of the predictive skill for weather regimes, reveals strengths and weaknesses of each model, and thus increases our confidence in the forecasts and their usefulness for decision‐making.〈/p〉

Beschreibung: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉This study is the first sub‐seasonal multi‐model assessment of seven year‐round weather regimes in the Atlantic–European domain. Greenland blocking tends to have the longest year‐round skill horizon for all models, especially in winter. The skill is lowest for the European blocking regime for all models, followed by Scandinavian blocking. Variability in the occurrence of no regime partly explains the predictability gap between the transition seasons and winter and summer. 〈boxed-text position="anchor" id="qj4512-blkfxd-0001" content-type="graphic" xml:lang="en"〉〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:00359009:media:qj4512:qj4512-toc-0001"〉 〈/graphic〉 〈/boxed-text〉〈/p〉

Beschreibung: Helmholtz Association http://dx.doi.org/10.13039/501100001656

Beschreibung: AXPO Solutions AGN/A

Beschreibung: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Flow‐dependent errors in tropical analyses and short‐range forecasts are analysed using global observing‐system simulation experiments assimilating only temperature, only winds, and both data types using the ensemble Kalman filter (EnKF) Data Assimilation Research Testbed (DART) and a perfect model framework. The idealised, homogeneous observation network provides profiles of wind and temperature data from the nature run for January 2018 using the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM) forced by the observed sea‐surface temperature. The results show that the assimilation of abundant wind observations in a perfect model makes the temperature data in the Tropics largely uninformative. Furthermore, the assimilation of wind data reduces the background errors in specific humidity twice as much as the assimilation of temperature observations. In all experiments, the largest analysis uncertainties and the largest short‐term forecast errors are found in regions of strong vertical and longitudinal gradients in the background wind, especially in the upper troposphere and lower stratosphere over the Indian Ocean and Maritime Continent. The horizontal error correlation scales are on average short throughout the troposphere, just several hundred km. The correlation scales of the wind variables in precipitating regions are half of those in nonprecipitating regions. In precipitating regions, the correlations are elongated vertically, especially for the wind variables. Strong positive cross‐correlations between temperature and specific humidity in the precipitating regions are explained using the Clausius–Clapeyron equation.〈/p〉

Beschreibung: China Scholarship Council http://dx.doi.org/10.13039/501100004543

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉High spatio‐temporal resolution near‐surface projected data is vital for climate change impact studies and adaptation. We derived the highest statistically downscaled resolution multivariate ensemble currently available: daily 1 km until the end of the century. Deep learning models were employed to develop transfer functions for precipitation, water vapor pressure, radiation, wind speed, and, maximum, mean and minimum temperature. Perfect prognosis is the particular statistical downscaling methodology applied, using a subset of the ReKIS data set for Saxony as predictands, the ERA5 reanalysis as during‐training predictors and the CORDEX‐EUR11 ensemble as projected predictors. The performance of the transfer functions was validated with the VALUE framework, yielding highly satisfactory results. Particular attention was given to the three major perfect prognosis assumptions, for which several tests were carried out and thoroughly discussed. From the latter, we corroborated their fulfillment to a high degree, thus, the derived projections are considered adequate and relevant for impact modelers. In total, 18 runs for RCP85, 1 for RCP45, and 4 for RCP26 were downscaled under both stochastic and deterministic approaches. This multivariate ensemble could drive more accurate and diverse impact studies in the region. Generally, the projected climatologies are in agreement with coarser resolution projections. Nevertheless, statistical particularities were observed for some projections, thus, a list of caveats for potential users is given. Due to the scalability of the presented methodology, further possible applications with additional datasets are proposed. Lastly, several potential improvement prospects are discussed toward the ideal subsequent iteration of the perfect prognosis statistical downscaling methodology.〈/p〉

Beschreibung: Plain Language Summary: There is a great worldwide demand for high spatio‐temporal resolution projections to develop climate change adaptation and mitigation schemes. Despite recent improvements, the resolution of both global and regional climate models is still too coarse to properly represent local variability, particularly in complex terrains. Depending on the application, impact modelers and decision makers require kilometer‐scale projections, with a minimum daily temporal resolution, of near‐surface variables. To fill this information gap, we employed artificial intelligence algorithms to downscale, to a novel daily 1 km resolution, a projection ensemble until the end of the century consisting of precipitation, water vapor pressure, radiation, wind speed, and, maximum, mean and minimum temperature. The ensemble comprises 18 runs of the business‐as‐usual worst‐case scenario (RCP85), 1 run of the stabilization scenario (RCP45), and 4 of the optimistic low‐emissions scenario (RCP26). The main assumptions of the methodology were thoroughly tested and discussed. The validation carried out yielded highly satisfactory results. Thus, we consider the projections to be adequate and relevant for impact studies. The region studied is located in Saxony (Germany), still, the methodology shown is potentially applicable anywhere in the world.〈/p〉

Beschreibung: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Highest statistically downscaled spatio‐temporal resolution multivariate ensemble currently available, consisting of 23 projection runs〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉We downscaled precipitation, water vapor pressure, radiation, wind speed, and, maximum, mean and minimum temperature〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The methodology complied to a high degree with the three perfect prognosis assumptions and is scalable to other spatio‐temporal resolutions〈/p〉〈/list-item〉 〈/list〉 〈/p〉

Beschreibung: European Social Fund, Freistaat Sachsen http://dx.doi.org/10.13039/501100004895

Beschreibung: https://rekis.hydro.tu-dresden.de/

Beschreibung: https://doi.org/10.5281/zenodo.7570247

Beschreibung: https://doi.org/10.5281/zenodo.7559173

Beschreibung: https://doi.org/10.5281/zenodo.7558945

Beschreibung: https://doi.org/10.5281/zenodo.8059248

Beschreibung: https://doi.org/10.5281/zenodo.8198925

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The usually short lifetime of convective storms and their rapid development during unstable weather conditions makes forecasting these storms challenging. It is necessary, therefore, to improve the procedures for estimating the storms' expected life cycles, including the storms' lifetime, size, and intensity development. We present an analysis of the life cycles of convective cells in Germany, focusing on the relevance of the prevailing atmospheric conditions. Using data from the radar‐based cell detection and tracking algorithm KONRAD of the German Weather Service, the life cycles of isolated convective storms are analysed for the summer half‐years from 2011 to 2016. In addition, numerous convection‐relevant atmospheric ambient variables (e.g., deep‐layer shear, convective available potential energy, lifted index), which were calculated using high‐resolution COSMO‐EU assimilation analyses (0.0625°), are combined with the life cycles. The statistical analyses of the life cycles reveal that rapid initial area growth supports wider horizontal expansion of a cell in the subsequent development and, indirectly, a longer lifetime. Specifically, the information about the initial horizontal cell area is the most important predictor for the lifetime and expected maximum cell area during the life cycle. However, its predictive skill turns out to be moderate at most, but still considerably higher than the skill of any ambient variable is. Of the latter, measures of midtropospheric mean wind and vertical wind shear are most suitable for distinguishing between convective cells with short lifetime and those with long lifetime. Higher thermal instability is associated with faster initial growth, thus favouring larger and longer living cells. A detailed objective correlation analysis between ambient variables, coupled with analyses discriminating groups of different lifetime and maximum cell area, makes it possible to gain new insights into their statistical connections. The results of this study provide guidance for predictor selection and advancements of nowcasting applications.〈/p〉

Beschreibung: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Based on a combination of data of the cell tracking algorithm KONRAD of the German Weather Service and COSMO‐EU model analyses for the summer half‐years from 2011 to 2016, statistical relationships between storm attributes (lifetime and maximum horizontal area), and ambient variables as well as the storms' history are quantified. The initial growth of the cell area is a better indicator of the lifetime and maximum area than ambient variables are. Of the latter, measures of the midtropospheric wind and vertical wind shear, in particular, are most suitable for distinguishing between convective cells with short and long lifetimes, whereas higher convective instability favours larger cells. 〈boxed-text position="anchor" id="qj4505-blkfxd-0001" content-type="graphic" xml:lang="en"〉〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:00359009:media:qj4505:qj4505-toc-0001"〉 〈/graphic〉 〈/boxed-text〉〈/p〉

Beschreibung: Bundesministerium für Digitales und Verkehr http://dx.doi.org/10.13039/100008383

Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉As projected by multiple climate models, short‐duration heavy precipitation events (SDHPEs) are expected to intensify particularly quickly under the changing climate posing substantial risk to natural and human systems. Yet over the years, SDHPEs have received less scientific attention than long‐duration heavy precipitation events (LDHPEs), mainly due to the limitations of measurement systems. Our aim is to provide insight into spatial and temporal variability of SDHPEs detected by the radar network of the 〈italic toggle="no"〉Deutscher Wetterdienst〈/italic〉 (DWD) in Germany from 2001 to 2020 as well as to explore their links to circulation patterns (CPs). The study is based on the Catalogue of Radar‐based heavy Rainfall Events (CatRaRE) generated using reprocessed gauge‐adjusted data of the DWD radar network as well as a new numerical method for classifying CPs over Central Europe called “〈italic toggle="no"〉Großwetterlagen〈/italic〉 for Reanalyses” (GWL‐REA). The results have demonstrated that SDHPEs, which are defined based on either locally valid precipitation values with a return period of 5 years (CatRaRE T5) or absolute precipitation values equal to DWD Warning Level 3 (CatRaRE W3), are common phenomena occurring most frequently in the afternoon hours of the summer season. They constitute up to 90% of all heavy precipitation events included in the catalogues covering relatively small areas—the median area of SDHPEs ranges from 22 km〈sup〉2〈/sup〉 (CatRaRE T5) to 24 km〈sup〉2〈/sup〉 (CatRaRE W3), while the median area of LDHPEs ranges from 175 km〈sup〉2〈/sup〉 (CatRaRE W3) to 184 km〈sup〉2〈/sup〉 (CatRaRE T5). As compared to LDHPEs, SDHPEs are generated by a wider spectrum of circulation conditions, including not only cyclonic but also anticyclonic CPs. In the warm season, the anticyclonic CPs, often accompanied by air mass advection from the south, can induce high thermal instability leading to the development of relatively small, isolated convective cells, which often cannot be captured by rain gauge stations.〈/p〉

Beschreibung: Federal Ministry for Digital and Transport (BMDV)

Beschreibung: https://www.dwd.de/DE/leistungen/catrare/catrare.html

Beschreibung: Statistical analysis of reanalysis and observed data reveals that high dust surface mass concentration in northern Greenland is associated with a Pacific Decadal Oscillation like pattern in its negative phase in the North Pacific as well as with La Niña conditions in the tropical Pacific region. The sea surface temperature anomalies in the Pacific realm resemble the Interdecadal Pacific Oscillation (IPO). The associated atmospheric circulation pattern, in the form of a wave‐train from the North Pacific to the Eurasian continent, favors enhanced dust uptake and transport toward the northern Greenland. Similar patterns are associated with a low‐resolution stacked record of five Ca2+ ice cores, that is, ngt03C93.2 (B16), ngt14C93.2 (B18), ngt27C94.2 (B21), GISP2−B, and NEEM‐2011‐S1, from northern Greenland, a proxy for regional dust concentration, during the last 400 years. We argue that northern Greenland ice core dust records could be used as proxies for the IPO and related teleconnections.

Beschreibung: Plain Language Summary: Observational and modeling studies show that, during the observational period, interannual to multidecadal dust concentration variability is related to the dominant modes of climate variability at these time scales. Here we show that Interdecadal Pacific Oscillation (IPO) signal is robustly recorded in low‐resolution dust ice core records from the northern Greenland during the last 400 years. We argue that northern Greenland ice core dust records could be used to put the IPO activity and related teleconnections during the observational period into a long‐term perspective.

Beschreibung: Key Points: Northern Greenland dust concentration variability shows global teleconnections during the instrumental period. The most stable pattern associated with northern Greenland ice core dust variability is the Interdecadal Pacific Oscillation (IPO). Northern Greenland ice core dust records could be used as a complementary source of information about IPO during the past.

Beschreibung: Changing Earth—Sustaining our Future

Beschreibung: Helmholtz Climate Initiative—REKLIM

Beschreibung: https://doi.org/10.1594/PANGAEA.57092

Beschreibung: https://doi.org/10.1594/PANGAEA.57294

Beschreibung: https://doi.org/10.1594/PANGAEA.107285

Beschreibung: https://doi.org/10.1594/PANGAEA.55536

Beschreibung: https://disc.gsfc.nasa.gov/datasets?project=MERRA-2

Beschreibung: https://psl.noaa.gov/data/gridded/data.cobe.html

Beschreibung: https://psl.noaa.gov/data/gridded/data.20thC_ReanV2c.html

Beschreibung: https://www.ncdc.noaa.gov/paleo-search/study/33092

Beschreibung: https://www.wdc-climate.de/ui/entry?acronym=EKF400_v2.0

Beschreibung: Ridging South Atlantic Anticyclones contribute an important amount of precipitation over South Africa. Here, we use a global coupled climate model and the ERA5 reanalysis to separate for the first time ridging highs (RHs) based on whether they occur together with Rossby wave breaking (RWB) or not. We show that the former type of RHs are associated with more precipitation than the latter type. The mean sea level pressure anomalies caused by the two types of RHs are characterized by distinct patterns, leading to differences in the flow of moisture‐laden air onto land. We additionally find that RWB mediates the effect of climate change on RHs during the twenty‐first century. Consequently, RHs occurring without RWB exhibit little change, while those occurring with RWB contribute more precipitation over the southern and less precipitation over the northeastern South Africa in the future.

Beschreibung: Plain Language Summary: The high pressure system located above the South Atlantic Ocean occasionally extends eastward over South Africa, leading to winds that blow onshore and carry moisture from the warm waters of the Southwest Indian Ocean to the coast. These events, termed ridging highs (RHs), bring an important contribution to precipitation over the southern and eastern parts of South Africa. Their occurrence is related to the propagation and breaking of atmospheric waves at the boundary between the troposphere and the stratosphere. This study categorizes RHs based on the behavior of atmospheric waves above and shows that events that are accompanied by wave breaking result in more precipitation over South Africa. In addition, model simulations are used to investigate the impact of climate change during the twenty‐first century on RHs and the associated precipitation. Although the model predicts that in total South Africa will experience drier conditions in the future, RHs contribute to this drying trend only in the northeastern part of the country. In the southern part of South Africa, the model simulates that RHs will bring more precipitation in the future.

Beschreibung: Key Points: Ridging South Atlantic Anticyclones are accompanied by Rossby wave breaking (RWB) aloft in 44% of the cases. Ridging highs that are accompanied by RWB lead to more precipitation over South Africa than those that are not. Ridging highs bring more precipitation over the southern and less precipitation over the northeastern part of South Africa in the future.

Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347

Beschreibung: Water Research Commission http://dx.doi.org/10.13039/501100004424

Beschreibung: https://doi.org/10.5281/zenodo.6523956

Beschreibung: https://doi.org/10.24381/cds.bd0915c6

Beschreibung: https://psl.noaa.gov/data/gridded/data.cpc.globalprecip.html

Beschreibung: Atmospheric circulation is a key driver of climate variability, and the representation of atmospheric circulation modes in regional climate models (RCMs) can enhance the credibility of regional climate projections. This study examines the representation of large‐scale atmospheric circulation modes in Coupled Model Inter‐comparison Project phase 5 RCMs once driven by ERA‐Interim, and by two general circulation models (GCMs). The study region is Western Europe and the circulation modes are classified using the Promax rotated T‐mode principal component analysis. The results indicate that the RCMs can replicate the classified atmospheric modes as obtained from ERA5 reanalysis, though with biases dependent on the data providing the lateral boundary condition and the choice of RCM. When the boundary condition is provided by ERA‐Interim that is more consistent with observations, the simulated map types and the associating time series match well with their counterparts from ERA5. Further, on average, the multi‐model ensemble mean of the analysed RCMs, driven by ERA‐Interim, indicated a slight improvement in the representation of the modes obtained from ERA5. Conversely, when the RCMs are driven by the GCMs that are models without assimilation of observational data, the representation of the atmospheric modes, as obtained from ERA5, is relatively less accurate compared to when the RCMs are driven by ERA‐Interim. This suggests that the biases stem from the GCMs. On average, the representation of the modes was not improved in the multi‐model ensemble mean of the five analysed RCMs driven by either of the GCMs. However, when the best‐performed RCMs were selected on average the ensemble mean indicated a slight improvement. Moreover, the presence of the North Atlantic Oscillation (NAO) in the simulated modes depends also on the lateral boundary conditions. The relationship between the modes and the NAO was replicated only when the RCMs were driven by reanalysis. The results indicate that the forcing model is the main factor in reproducing the atmospheric circulation.

Beschreibung: Regional and local wind systems are often complex, particularly near coastal areas with a highly variable orography. Thus, the realistic representation of regional wind systems in weather and climate models is of strong relevance. Here, we evaluate the ability of a 13‐year convection‐permitting climate simulation in reproducing the interaction of several regional summer wind systems over the complex orography in the eastern Mediterranean region. The COSMO‐CLM simulations are driven by hourly ERA‐5 reanalysis and have a spatial resolution of 2.8 and 7.0 km. The simulated near‐surface wind fields are compared with unique very high‐resolution wind observations collected within the “Dead Sea Research Venue” project (DESERVE) and data from the Israel Meteorological Service synop network. The high‐resolution COSMO‐CLM simulations largely reproduce the main characteristics of the regional wind systems (Mediterranean and Dead Sea breeze, slope winds in the Judean Mountains and winds along the Jordan Rift valley), whereas ERA‐5 is only able to represent the Mediterranean Sea breeze. The high‐resolution simulations substantially improve the representation of regional winds, particularly over complex orography. Indeed, the 2.8 km simulation outperforms the 7.0 km run, on 88% of the days. Two mid‐July 2015 case studies show that only the 2.8 simulation can realistically simulate the penetration of the Mediterranean Sea Breeze into the Jordan Rift valley and complex interactions with other wind systems like the Dead Sea breeze. Our results may have profound implications for regional weather and climate prediction since very high‐resolution information seems to be necessary to reproduce the main summertime climatic features in this region. We envisage that such simulations may also be required at other regions with complex orography.

Beschreibung: In this paper we show that COSMO‐CLM regional climate model simulations at 7.0 (CLM‐7.0) and 2.8km (CLM‐2.8) resolution can realistically reproduce near‐surface regional and local wind systems over the complex orography of the eastern Mediterranean as opposite to coarser resolutions (ERA‐5, 31 km). The Mediterranean and local Dead Sea breezes, slope winds over the Judean Mountains, and winds along the Jordan Rift valley are well represented both climatologically and on individual days. CLM‐2.8 captures the small‐scale variability of the wind field better than CLM‐7.0 particularly near the Dead Sea and on 88% of the days CLM‐2.8 represents wind speed even more realistically than CLM‐7.0. image

Beschreibung: German Helmholtz Association (“Changing Earth” program)

Beschreibung: AXA Research Fund http://dx.doi.org/10.13039/501100001961

Beschreibung: Ministry of Science, Research and Arts

Beschreibung: Helmholtz Association of German Research Centers

Beschreibung: Climate model simulations typically exhibit a bias, which can be corrected using statistical approaches. In this study, a geostatistical approach for bias correction of daily precipitation at ungauged locations is presented. The method utilizes a double quantile mapping with dry day correction for future periods. The transfer function of the bias correction for the ungauged locations is established using distribution functions estimated by ordinary kriging with anisotropic variograms. The methodology was applied to the daily precipitation simulations of the entire CORDEX‐Africa ensemble for a study region located in the West African Sudanian Savanna. This ensemble consists of 23 regional climate models (RCM) that were run for three different future scenarios (RCP 2.6, RCP 4.5, and RCP 8.5). The evaluation of the approach for a historical 50‐year period (1950–2005) showed that the method can reduce the inherent strong precipitation bias of RCM simulations, thereby reproducing the main climatological features of the observed data. Moreover, the bias correction technique preserves the climate change signal of the uncorrected RCM simulations. However, the ensemble spread is increased due to an overestimation of the rainfall probability of uncorrected RCM simulations. The application of the bias correction method to the future period (2006–2100) revealed that annual precipitation increases for most models in the near (2020–2049) and far future (2070–2099) with a mean increase of up to 165mm⋅a−1 (18%). An analysis of the monthly and daily time series showed a slightly delayed onset and intensification of the rainy season.

Beschreibung: Adapting water management strategies to future precipitation projected by climate models is associated with high uncertainty in sparsely gauged catchments. Kriging was utilized to estimate distribution parameters for ungauged locations in a West African region to perform a bias correction of the CORDEX‐Africa ensemble. The application of the bias correction method revealed higher annual precipitation amounts and an intensifaction of the rainy season but only little change to the onset of the rainy season.

Beschreibung: German Federal Ministry of Education and Research, Bonn (BMBF), West African Science Service Centre on Climate Change and Adapted Land Use (WASCAL)

Beschreibung: Warming of the North Atlantic region in climate history often was associated with massive melting of the Greenland Ice Sheet. To identify the meltwater's impacts and isolate these from internal variability and other global warming factors, we run single‐forcing simulations including small ensembles using three complex climate models differing only in their ocean components. In 200‐year‐long preindustrial climate simulations, we identify robust consequences of abruptly increasing Greenland runoff by 0.05 Sv: sea level rise of 44 ± 10 cm, subpolar North Atlantic surface cooling of 0.7°C, and a moderate AMOC decline of 1.1–2.0 Sv. The latter two emerge in under three decades—and reverse on the same timescale after the perturbation ends in year 100. The ocean translates the step‐change perturbation into a multidecadal‐to‐centennial signature in the deep overturning circulation. In all simulations, internal variability creates notable uncertainty in estimating trends, time of emergence, and duration of the response.

Beschreibung: Plain Language Summary: Enhanced melting of Greenland's glaciers is considered to be a major player in past rapid climate transitions and anticipated to soon impact ocean circulation under current global warming. Global warming triggers complex processes and feedbacks, of which greater amounts of meltwater slowing the large‐scale ocean circulation is only one. To better understand the sensitivity of the real but also the model ocean to just this meltwater, we run idealized experiments with up‐to‐date climate models, which use the same atmosphere and land but different ocean components. We find that sea level rise, cooling of the North Atlantic region, and slowing of the ocean circulation are responses common to all models while regional magnitudes of these responses differ considerably. Once we stop adding freshwater, all three models show that surface temperature and ocean circulation recover as quickly (or slowly) as they changed at the beginning of the experiment. Sea level rise is a lasting impact though.

Beschreibung: Key Points: Sudden increase in Greenland freshwater release is turned into century scale change by deep ocean dynamics. Upper ocean responses to moderately enhanced freshwater release from Greenland reverse on the same timescale once release ceases. Ocean model formulation affects regional expressions but basin‐scale responses are robust, so is the timing on decadal to centennial scales.

Beschreibung: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347

Beschreibung: Accurate and reliable precipitation data with high spatial and temporal resolution are essential in studying climate variability, water resources management, and hydrological forecasting. A range of global precipitation data are available to this end, but how well these capture actual precipitation remains unknown, particularly for mountain regions where ground stations are sparse. We examined the performance of three global high‐resolution precipitation products for capturing precipitation over Central Asia, a hotspot of climate change, where reliable precipitation data are particularly scarce. Specifically, we evaluated MSWEP, CHIRPS, and GSMAP against independent gauging stations for the period 1985–2015. Our results show that MSWEP and CHIRPS outperformed GSMAP for wetter periods (i.e., winter and spring) and wetter locations (150–600 mm·year−1), lowlands, and mid‐altitudes (0–3,000 m), and regions dominated by winter and spring precipitation. MSWEP performed best in representing temporal precipitation dynamics and CHIRPS excelled in capturing the volume and distribution of precipitation. All precipitation products poorly estimated precipitation at higher elevations (〉3,000 m), in drier areas (〈150 mm), and in regions characterized by summer precipitation. All products accurately detected dry spells, but their performance decreased for wet spells with increasing precipitation intensity. In sum, we find that CHIRPS and MSWEP provide the most reliable high‐resolution precipitation estimates for Central Asia. However, the high spatial and temporal heterogeneity of the performance call for a careful selection of a suitable product for local applications considering the prevailing precipitation dynamics, climatic, and topographic conditions.

Beschreibung: We present the first quantitative evaluation of global high‐resolution (below 12 km) precipitation products against independent ground observations over Central Asia. Our results show that MSWEP was best at representing temporal precipitation dynamics, and CHIRPS was most prominent in representing the volume and distribution of precipitation. This is especially the case of wet seasons, altitudes below 3,000 m, and regions dominated by spring and winter precipitation. Our analysis provides key insights on the precipitation products' suitability for local hydrological applications.

Beschreibung: Leibniz‐Institut für Agrarentwicklung in Transformationsökonomien

Beschreibung: Volkswagen Foundation http://dx.doi.org/10.13039/501100001663

Beschreibung: Observation‐based and modeling studies have identified the Eastern Mediterranean and Middle East (EMME) region as a prominent climate change hotspot. While several initiatives have addressed the impacts of climate change in parts of the EMME, here we present an updated assessment, covering a wide range of timescales, phenomena and future pathways. Our assessment is based on a revised analysis of recent observations and projections and an extensive overview of the recent scientific literature on the causes and effects of regional climate change. Greenhouse gas emissions in the EMME are growing rapidly, surpassing those of the European Union, hence contributing significantly to climate change. Over the past half‐century and especially during recent decades, the EMME has warmed significantly faster than other inhabited regions. At the same time, changes in the hydrological cycle have become evident. The observed recent temperature increase of about 0.45°C per decade is projected to continue, although strong global greenhouse gas emission reductions could moderate this trend. In addition to projected changes in mean climate conditions, we call attention to extreme weather events with potentially disruptive societal impacts. These include the strongly increasing severity and duration of heatwaves, droughts and dust storms, as well as torrential rain events that can trigger flash floods. Our review is complemented by a discussion of atmospheric pollution and land‐use change in the region, including urbanization, desertification and forest fires. Finally, we identify sectors that may be critically affected and formulate adaptation and research recommendations toward greater resilience of the EMME region to climate change.

Beschreibung: Key Points: The Eastern Mediterranean and Middle East is warming almost two times faster than the global average and other inhabited parts of the world. Climate projections indicate a future warming, strongest in summers. Precipitation will likely decrease, particularly in the Mediterranean. Virtually all socio‐economic sectors will be critically affected by the projected changes.

Beschreibung: European Union Horizon 2020

Beschreibung: https://esg-dn1.nsc.liu.se/search/esgf-liu/

Beschreibung: In this paper we coupled a crop growth model to the Weather Research and Forecasting model with its land surface model Noah‐MP and demonstrated the influence of the weather driven crop growth on land‐atmosphere (L‐A) feedback. An impact study was performed at the convection permitting scale of 3 km over Germany. While the leaf area index (LAI) in the control simulation was the same for all cropland grid cells, the inclusion of the crop growth model resulted in heterogeneous crop development with higher LAI and stronger seasonality. For the analyses of L‐A coupling, a two‐legged metric was applied based on soil moisture, latent heat flux and convective available potential energy. Weak atmospheric coupling is enhanced by the crop model, the terrestrial coupling determines the regions with the L‐A feedback. The inclusion of the crop model turns regions with no L‐A feedback on this path into regions with strong positive coupling. The number of non‐atmospherically controlled days between April and August is increased by 10–15 days in more than 50% of Germany. Our work shows that this impact results in a reduction of both cold bias and warm biases and thus improves the metrics of distributed added value of the monthly mean temperatures. The study confirms that the simulation of the weather driven annual phenological development of croplands for the regional climate simulations in mid‐latitudes is crucial due to the L‐A feedback processes and the currently observed and expected future change in phenological phases.

Beschreibung: Key Points: Coupling a crop growth model with the Weather and Research Forecasting model significantly improves the simulation of the leaf area index. Land‐atmosphere coupling strength is enhanced by weather dependent crop growth simulation. The distributed added value metric shows a reduction in temperature biases of up to 80% in croplands throughout the season in Germany.

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: https://opendata.dwd.de/climate_environment/CDC/grids_germany/daily/Project_TRY/air_temperature_mean/

Beschreibung: https://doi.org/10.5281/zenodo.6501984

Beschreibung: http://land.copernicus.eu/pan-european/corine-land-cover/clc-2006/view

Beschreibung: https://doi.org/10.1594/WDCC/WRF_NOAH_HWSD_world_TOP_SOILTYP

Beschreibung: In‐depth understanding of the potential implications of climate change is required to guide decision‐ and policy‐makers when developing adaptation strategies and designing infrastructure suitable for future conditions. Impact models that translate potential future climate conditions into variables of interest are needed to create the causal connection between a changing climate and its impact for different sectors. Recent surveys suggest that the primary strategy for validating such models (and hence for justifying their use) heavily relies on assessing the accuracy of model simulations by comparing them against historical observations. We argue that such a comparison is necessary and valuable, but not sufficient to achieve a comprehensive evaluation of climate change impact models. We believe that a complementary, largely observation‐independent, step of model evaluation is needed to ensure more transparency of model behavior and greater robustness of scenario‐based analyses. This step should address the following four questions: (1) Do modeled dominant process controls match our system perception? (2) Is my model's sensitivity to changing forcing as expected? (3) Do modeled decision levers show adequate influence? (4) Can we attribute uncertainty sources throughout the projection horizon? We believe that global sensitivity analysis, with its ability to investigate a model's response to joint variations of multiple inputs in a structured way, offers a coherent approach to address all four questions comprehensively. Such additional model evaluation would strengthen stakeholder confidence in model projections and, therefore, into the adaptation strategies derived with the help of impact models.

Beschreibung: A comprehensive evaluation of climate change impact models combining both observation‐based and response‐based strategies.

Beschreibung: This article is categorized under: Climate Models and Modeling 〉 Knowledge Generation with Models Assessing Impacts of Climate Change 〉 Evaluating Future Impacts of Climate Change

Beschreibung: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156

Beschreibung: Engineering and Physical Sciences Research Council http://dx.doi.org/10.13039/501100000266

Beschreibung: The moisture sources of precipitation in the Tianshan Mountains, one of the regions with the highest precipitation in Central Asia during 1979–2017 are comprehensively and quantitatively summarized by using a Lagrangian moisture source detection technique. Continental sources provide about 93.2% of the moisture for precipitation in the Tianshan Mountain, while moisture directly from the ocean is very limited, averaging only 6.8%. Central Asia plays a dominant role in providing moisture for all sub‐regions of the Tianshan Mountains. For the Western Tianshan, moisture from April to October comes mainly from Central Asia (41.4%), while moisture from November to March is derived primarily from Western Asia (45.7%). Nearly 13.0% of moisture to precipitation for Eastern Tianshan in summer originates from East and South Asia, and the Siberia region. There is a significant decreasing trend in the moisture contribution of local evaporation and Central Asia in the Eastern Tianshan during winter. The contribution of moisture from Europe to summer precipitation in the Central and Eastern Tianshan and the contribution of the North Atlantic Ocean to summer precipitation in the Northern, Central, and Eastern Tianshan also exhibit a decreasing trend. The largest increase in moisture in Western Tianshan stems from West Asia during extreme winter precipitation months. Europe is also an important contributor to extreme precipitation in the Northern Tianshan. The moisture from East and South Asia and Siberia during extreme precipitation months in both winter and summer is significantly enhanced in the Eastern Tianshan.

Beschreibung: Key Points: Local evaporation and Central Asia play a leading role in providing moisture for all sub‐regions of the Tianshan Mountains. The largest moisture component during the months of extreme winter precipitation for Western Tianshan derives from western Asia. Moisture from East and South Asia and Siberia during extreme precipitation months is significantly enhanced in the Eastern Tianshan.

Beschreibung: China Scholarship Council

Beschreibung: Humboldt‐Universität zu Berlin

Beschreibung: https://zenodo.org/record/6451656#.YrrfbqhBwuU

Beschreibung: The significant climate feedback of stratospheric water vapor (SWV) necessitates quantitative estimates of SWV budget changes. Model simulations driven by the newest European Centre for Medium‐Range Weather Forecast reanalysis ERA5, satellite observations from the Stratospheric Water and OzOne Satellite Homogenized data set, Microwave Limb Sounder, and in situ frost point hygrometer observations from Boulder all show substantial and persistent stratospheric moistening after a sharp drop in water vapor at the turn of the millennium. This moistening occurred mainly during 2000–2006 and SWV abundances then remained high over the last decade. We find strong positive trends in the Northern Hemisphere and weak negative trends over the South Pole, mainly during austral winter. Moistening of the tropical stratosphere after 2000 occurred during late boreal winter/spring, reached values of ∼0.2 ppm/decade, was well correlated with a warming of the cold point tropopause by ∼0.4 K/decade and can only be partially attributed to El Nino‐Southern Oscillation and volcanic eruptions.

Beschreibung: Plain Language Summary: Water vapor is an effective greenhouse gas. Human‐induced climate change has led to warmer air in the troposphere, which consequently can hold more moisture, thus enhancing the greenhouse effect. The long‐term change in stratospheric water vapor (SWV) is less clear and currently under debate. Using satellite observations, balloon soundings and model simulations, we find an increase of SWV after 2000. This moistening occurred mainly during 2000–2006 and the stratospheric moisture content then remained high over the last decade. The increase of SWV is stronger in the Northern than in the Southern Hemisphere. Over the South Pole, a weak decrease was found. Moistening of the tropical stratosphere occurred mainly during late winter and spring, and was in line with warming of the tropical tropopause, the coldest region that separates the troposphere and stratosphere. Natural causes such as volcanic eruptions cannot completely explain this stratospheric moistening.

Beschreibung: Key Points: Stratospheric moistening after 2000 is clearly detectable in ERA5‐driven simulations, satellite and in situ observations. Hemispheric asymmetry is found with strong positive trends in the Northern Hemisphere and weak negative trends over the South Pole. Moistening of the lower tropical stratosphere is only partially caused by El Nino‐Southern Oscillation and volcanic eruptions.

Beschreibung: https://doi.org/10.5067/Aura/MLS/DATA2508

Beschreibung: https://doi.org/10.5067/GLOSSAC-L3-V2.0

Beschreibung: https://doi.org/10.5067/GLOSSAC-L3-V2.0

Beschreibung: Worldwide, rice production contributes about 10% of total greenhouse gas (GHG) emissions from the agricultural sector, mainly due to CH4 emissions from continuously flooded fields. Alternate Wetting and Drying (AWD) is a promising crop technology for mitigating CH4 emissions and reducing the irrigation water currently being applied in many of the world's top rice‐producing countries. However, decreased emissions of CH4 may be partially counterbalanced by increased N2O emissions. In this case study for the Philippines, the national mitigation potential of AWD is explored using the process‐based biogeochemical model LandscapeDNDC. Simulated mean annual CH4 emissions under conventional rice production for the time period 2000–2011 are estimated as 1,180 ± 163 Gg CH4 yr−1. During the cropping season, this is about +16% higher than a former estimate using emission factors. Scenario simulations of nationwide introduction of AWD in irrigated landscapes suggest a considerable decrease in CH4 emissions by −23%, while N2O emissions are only increased by +8%. Irrespective of field management, at national scale, the radiative forcing of irrigated rice production is always dominated by CH4 (〉95%). The reduction potential of GHG emissions depends on, for example, number of crops per year, residue management, amount of applied irrigation water, and sand content. Seasonal weather conditions also play an important role since the mitigation potential of AWD is almost double as high in dry as compared to wet seasons. Furthermore, this study demonstrates the importance of temporal continuity, considering off‐season emissions and the long‐term development of GHG emissions across multiple years.

Beschreibung: Plain Language Summary: Worldwide, rice production contributes to about 10% of total greenhouse gas emissions of the agricultural sector mainly due to CH4 emissions from fields that are continuously flooded. Alternate Wetting and Drying (AWD) is an alternative cropping practice where fields are irrigated a few days after the disappearance of the ponded water. This study explores the mitigation potential of nationwide introduction of AWD in the Philippines. Results from the application of a process‐based model suggest a considerable decrease in CH4 emissions by −23%. Compared to N2O, CH4 is responsible for more than 95% of the total radiative forcing under conventional or AWD field management.

Beschreibung: Key Points: Nationwide, Alternate Wetting and Drying (AWD) reduces CH4 emissions by −23%. N2O emissions contribute to less than 5% to the total radiative forcing under conventional or AWD field management. Mitigation of AWD depends on, for example, seasonal weather conditions, cropping intensity, irrigation, residue management, and soil texture.

Beschreibung: DFG

Beschreibung: https://doi.org/10.35097/588

Beschreibung: Natural forcing from solar and volcanic activity contributes significantly to climate variability. The post‐eruption cooling of strong volcanic eruptions was hypothesized to have led to millennial‐scale variability during Glacials. Cooling induced by volcanic eruption is potentially weaker in the warmer climate. The underlying question is whether the climatic response to natural forcing is state‐dependent. Here, we quantify the response to natural forcing under Last Glacial and Pre‐Industrial conditions in an ensemble of climate model simulations. We evaluate internal and forced variability on annual to multicentennial scales. The global temperature response reveals no state dependency. Small local differences result mainly from state‐dependent sea ice changes. Variability in forced simulations matches paleoclimate reconstructions significantly better than in unforced scenarios. Considering natural forcing is therefore important for model‐data comparison and future projections.

Beschreibung: Plain Language Summary: Climate variability describes the spatial and temporal variations of Earth's climate. Understanding these variations is important for estimating the occurrence of extreme climate events such as droughts. Yet, it is unclear whether climate variability depends on the mean surface temperature of the Earth or not. Here, we investigate the effects of natural forcing from volcanic eruptions and solar activity changes on climate variability. We compare simulations of a past (cold) and present (warm) climate with and without volcanism and solar changes. We find that overall, the climate system responds similarly to natural forcing in the cold and warm state. Small local differences mainly occur where ice can form. To evaluate the simulated variability, we use data from paleoclimate archives, including trees, ice‐cores, and marine sediments. Climate variability from forced simulations agrees better with the temperature variability obtained from data. Natural forcing is therefore critical for reliable simulation of variability in past and future climates.

Beschreibung: Key Points: We present Glacial/Interglacial climate simulations and quantify effects of time‐varying volcanic and solar forcing on climate variability. The mean global and local response to these forcings is similar in Glacial and Interglacial climate, suggesting low state dependency. In both climate states, modeled temperature variance agrees better with palaeoclimate data when volcanic and solar forcing is included.

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: Heinrich Böll Stiftung (Heinrich Böll Foundation) http://dx.doi.org/10.13039/100009379

Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347

Beschreibung: https://doi.org/10.5281/zenodo.6074747

Beschreibung: https://github.com/paleovar/StateDependency

Beschreibung: https://doi.org/10.5281/zenodo.6474769

Beschreibung: The Madden–Julian oscillation (MJO) is the dominant component of tropical intraseasonal variability, with wide‐reaching impacts even on extratropical weather and climate patterns. However, predicting the MJO is challenging. One reason is the suboptimal state estimates obtained with standard data assimilation (DA) approaches. These are typically based on filtering methods with Gaussian approximations and do not take into account physical properties that are important specifically for the MJO. In this article, a constrained ensemble DA method is applied to study the impact of different physical constraints on the state estimation and prediction of the MJO. The quadratic programming ensemble (QPEns) algorithm utilized extends the standard stochastic ensemble Kalman filter (EnKF) with specifiable constraints on the updates of all ensemble members. This allows us to recover physically more consistent states and to respect possible associated non‐Gaussian statistics. The study is based on identical twin experiments with an adopted nonlinear model for tropical intraseasonal variability. This so‐called skeleton model succeeds in reproducing the main large‐scale features of the MJO and closely related tropical waves, while keeping adequate simplicity for fast experiments on intraseasonal time‐scales. Conservation laws and other crucial physical properties from the model are examined as constraints in the QPEns. Our results demonstrate an overall improvement in the filtering and forecast skill when the model's total energy is conserved in the initial conditions. The degree of benefit is found to be dependent on the observational setup and the strength of the model's nonlinear dynamics. It is also shown that, even in cases where the statistical error in some waves remains comparable with the stochastic EnKF during the DA stage, their prediction is improved remarkably when using the initial state resulting from the QPEns.

Beschreibung: Unsatisfactory predictions of the MJO are partly due to DA methods that do not respect non‐Gaussian PDFs and the physical properties of the tropical atmosphere. Therefore the QPEns, an algorithm extending a stochastic EnKF with state constraints, is tested here on a simplified model for the MJO and associated tropical waves. Our series of identical twin experiments shows, in particular, that a constraint on the truth's nonlinear total energy improves forecasts statistically and can, in certain situations, even prevent filter divergence. image

Beschreibung: Deutsche Forschungsgemeinschaft : Heisenberg Award (DFG JA1077/4‐1); Transregional Collaborative Research Center SFB / TRR 165 “Waves to Weather” http://dx.doi.org/10.13039/501100001659

Beschreibung: Office of Naval Research (ONR) http://dx.doi.org/10.13039/100000006

Beschreibung: Abundant rainfall over tropical land masses sustains rich ecosystems, a crucial source of biodiversity and sink of carbon. Here, we use two characteristics of the observed tropical precipitation distribution, its distinctive zonal arrangement and its partitioning between land and ocean, to understand whether land conditions the climate to receive more than its fair share of precipitation as set by the land‐sea distribution. Our analysis demonstrates that it is not possible to explain the tropics‐wide partitioning of precipitation unless one assumes that rain is favored over land. Land receives more than its fair share of precipitation by broadening and letting the tropical rainbelts move more, effectively underpinning a negative feedback between surface water storage and precipitation. In contrast, rain is disfavored over land in climate models. Our findings suggest that the abundance of rainfall that shapes the terrestrial tropical biosphere is more robust to perturbations than models have suggested.

Beschreibung: Plain Language Summary: Many ecosystems depend on the presence of a land surface exposed to precipitation to exist and prosper. In contrast to the marine biota, though, the terrestrial biosphere cannot directly tap into an unlimited reservoir of water molecules that can be recycled to support life. Yet, observations indicate that it rains in mean 3 mm day−1 over tropical land and 3 mm day−1 over tropical ocean, giving the surprising impression that precipitation amounts are not altered by the presence of land. Investigating the factors controlling this tropics‐wide partitioning of precipitation, we show that geometrical constraints actually would lead to a precipitation ratio of 0.86, not 1.0, if the presence of land would not matter. Comparing this theoretical value to observations, we find that the land receives more than its fair share of precipitation. This happens by broadening and letting the tropical rainbelt moves more over land. By quantifying the strength of the land control on the tropics‐wide partitioning of precipitation, we can also deduce that a negative feedback exists between evapotranspiration and precipitation. In contrast, repeating the same analysis with climate models reveals a positive feedback, questioning the ability of climate models to simulate regional tropical precipitation changes.

Beschreibung: Key Points: A conceptual model of tropical precipitation is derived to understand the tropics‐wide partitioning of precipitation between land and ocean. The size and location of continent constrain the tropical land‐to‐ocean precipitation ratio to lie between 0.74 and 0.95 with a mean of 0.86. Observed ratios from six data sets are larger than these values, indicating that land receives more than its fair share of precipitation.

Beschreibung: http://hdl.handle.net/21.11116/0000-000A-1DEC-D

Beschreibung: High ground‐level ozone concentrations and high air temperatures present two health‐relevant natural hazards. The most severe health outcomes are generally associated with concurrent elevated levels of both variables, representing so‐called compound ozone and temperature (o‐t‐) events. These o‐t‐events, their relationship with identified main meteorological and synoptic drivers, as well as ozone and temperature levels themselves and the linkage between both variables, vary temporally and with the location of sites. Due to the serious health burden and its spatiotemporal variations, the analysis of o‐t‐events across the European domain represents the focus of the current work. The main objective is to model and project present and future o‐t‐events, taking region‐specific differences into account. Thus, a division of the European domain into six o‐t‐regions with homogeneous, similar ground‐level ozone and temperature characteristics and patterns built the basis of the study. In order to assess region‐specific main meteorological and synoptic drivers of o‐t‐events, statistical downscaling models were developed for selected representative stations per o‐t‐region. Statistical climate change projections for all central European o‐t‐regions were generated to assess potential frequency shifts of o‐t‐events until the end of the 21st century. The output of eight Earth System Models from the sixth phase of the Coupled Model Intercomparison Project considering SSP245 and SSP370 scenario assumptions was applied. By comparing midcentury (2041–2060) and late century (2081–2100) time slice differences with respect to a historical base period (1995–2014), substantial increases of the health‐relevant compound o‐t‐events were projected across all central European regions.

Beschreibung: Plain Language Summary: Compound events with concurrent high levels of ozone, being a major pollutant present in the air near Earth's surface, and of air temperature, have strong negative impacts on the health of humans. In this study, these compound events were investigated under present and future European climate. Six regions of similar ozone and temperature characteristics and patterns were defined. For each region, representative stations being typical examples for the overall region were extracted. Models for these stations were developed and their results analyzed to define factors that highly influence the occurrence of compound ozone and temperature events in each region, for example, mean air temperature or humidity levels. The generated models were later applied to project future frequency shifts of these compound events under climate change in central Europe. As a major result of the study, the future health‐relevant compound ozone and temperature events were projected to occur more frequently in the middle as well as at the end of the 21st century across all central European regions.

Beschreibung: Key Points: A clustering approach based on ground‐level ozone and air temperature leads to a division of Europe into six ozone and temperature regions. Statistical downscaling models identify region‐specific main meteorological and synoptic drivers of compound ozone and temperature events. Climate change projections point to an increase in these compound events until the end of the 21st century in central Europe.

Beschreibung: Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)

Beschreibung: During the period 2018–2020, Europe experienced a series of hot and dry weather conditions with significant socioeconomic and environmental consequences. Yet, the extremity of these multi‐year dry conditions is not recognized. Here, we provide a comprehensive spatio‐temporal assessment of the drought hazard over Europe by benchmarking past exceptional events during the period from 1766 to 2020. We identified the 2018–2020 drought event as a new benchmark having an unprecedented intensity that persisted for more than 2 years, exhibiting a mean areal coverage of 35.6% and an average duration of 12.2 months. What makes this event truly exceptional compared with past events is its near‐surface air temperature anomaly reaching +2.8 K, which constitutes a further evidence that the ongoing global warming is exacerbating present drought events. Furthermore, future events based on climate model simulations Coupled Model Intercomparison Project v5 suggest that Europe should be prepared for events of comparable intensity as the 2018–2020 event but with durations longer than any of those experienced in the last 250 years. Our study thus emphasizes the urgent need for adaption and mitigation strategies to cope with such multi‐year drought events across Europe.

Beschreibung: Plain Language Summary: This manuscript demonstrates that the 2018–2020 multi‐year drought event constitutes a new benchmark in Europe, with an unprecedented level of intensity over the past 250 years. What makes this event truly exceptional compared with past events is its temperature anomaly reaching +2.8 K. This finding provides new evidence that the ongoing global warming exacerbates current drought events. The key message of this study is that the projected future events across the European continent will have a comparable intensity as the 2018–2020 drought but exhibit considerably longer durations than any of those observed during the last 250 years. Our analysis also shows that these exceptional temperature‐enhanced droughts significantly negatively impact commodity crops across Europe.

Beschreibung: Key Points: The 2018–2020 multi‐year drought shows unprecedented level of intensity during the past 250 years. The 2018–2020 event reached record‐breaking +2.8 K temperature anomaly and negatively impacted major crops. Future drought events reach comparable intensity of 2018–2020 but with considerably longer durations.

Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659

Beschreibung: Grantová Agentura České Republiky (GAČR) http://dx.doi.org/10.13039/501100001824

Beschreibung: Helmholtz‐Fonds (Helmholtz‐Fonds e.V.) http://dx.doi.org/10.13039/501100013655

Beschreibung: Variability of the North Atlantic Oscillation (NAO) drives wintertime temperature anomalies in the Northern Hemisphere. Dynamical seasonal prediction systems can skilfully predict the winter NAO. However, prediction of the NAO‐dependent air temperature anomalies remains elusive, partially due to the low variability of predicted NAO. Here, we demonstrate a hidden potential of a multi‐model ensemble of operational seasonal prediction systems for predicting wintertime temperature by increasing the variability of predicted NAO. We identify and subsample those ensemble members which are close to NAO index statistically estimated from initial autumn conditions. In our novel multi‐model approach, the correlation prediction skill for wintertime Central Europe temperature is improved from 0.25 to 0.66, accompanied by an increased winter NAO prediction skill of 0.9. Thereby, temperature anomalies can be skilfully predicted for the upcoming winter over a large part of the Northern Hemisphere through increased variability and skill of predicted NAO.

Beschreibung: Plain Language Summary: Wintertime temperature in the Northern Hemisphere is regulated by the variations of atmospheric pressure, represented by the so‐called North Atlantic Oscillation (NAO). The NAO's phase—negative or positive—is associated with the pathways of cold and warm air masses leading to cold or warm winters in Europe. While the NAO phase can be predicted well, predictions of the NAO‐dependent air temperature remain elusive. Specifically, it is challenging to predict the strength of the NAO, the most important requirement for the accurate prediction of wintertime temperature. Here, we improve wintertime temperature prediction by increasing the strength of the predicted NAO. We use observation based autumn Northern Hemisphere ocean and air temperature, as well as ice and snow cover for statistical estimation of the first guess NAO for the upcoming winter. Then, we sub‐select only those simulations from the multi‐model ensemble, which are consistent with our first guess NAO. As a result, based on these selected members, the wintertime temperature prediction is substantially improved over a large part of the Northern Hemisphere.

Beschreibung: Key Points: Amplitude and skill of predicted North Atlantic Oscillation (NAO) improve significantly by subsampling of ensemble of existing seasonal prediction systems. Amplified NAO variability leads to significant improvement in predicting the upcoming winter temperature anomalies in the Northern Hemisphere.

Beschreibung: Deutsche Forschungsgemeinschaft

Beschreibung: Climate, Climatic Change, and Society

Beschreibung: Marine Institute grant

Beschreibung: European Union's Horizon 2020 research and innovation programme

Beschreibung: https://cds.climate.copernicus.eu/cdsapp#!/dataset/seasonal-original-single-levels?tab=overview

Beschreibung: http://www.ecmwf.int/en/forecasts/datasets

Beschreibung: Hydrological extreme events are generated by different sequences of hydrometeorological drivers, the importance of which may vary within the sample of drought events. Here, we investigate how the importance of different hydrometeorological driver sequences varies by event magnitude using a large sample of catchments in Europe. To do so, we develop an automated classification scheme for streamflow drought events. The classification scheme standardizes a previous qualitative drought typology and assigns events to one of eight drought event types—each characterized by a set of single or compounding drivers—using information about seasonality, precipitation deficits, and snow availability. The objective event classification reveals how drought drivers vary not just in space and by season, but also with event magnitude. Specifically, we show that (a) rainfall deficit droughts and cold snow season droughts are the dominant drought event type in Western Europe and Eastern and Northern Europe, respectively; (b) rainfall deficit and cold snow season droughts are important from autumn to spring while snowmelt and wet‐to‐dry season droughts are important in summer; and (c) moderate droughts are mainly driven by rainfall deficits while severe events are mainly driven by snowmelt deficits in colder climates and by streamflow deficits transitioning from the wet to the dry season in warmer climates. These differences in sequences of drought generation mechanisms for severe and moderate events suggest that future changes in hydrometeorological drivers may affect moderate and severe events differently.

Beschreibung: Key Points: We develop a standardized and objective classification scheme for streamflow droughts using hydroclimatic information. The most severe drought events are governed by other processes than moderate events. Moderate droughts are dominated by rainfall deficits and severe droughts by snowmelt deficits or prolonged rainfall deficit droughts.

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: EC/H2020/PRIORITY 'Excellent science'/H2020 European Research Council http://dx.doi.org/10.13039/100010663

Beschreibung: https://www.bafg.de/GRDC/EN/02_srvcs/21_tmsrs/riverdischarge_node.html

Beschreibung: https://doi.pangaea.de/10.1594/PANGAEA.887470

Beschreibung: https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-land?tab=overview

Beschreibung: http://www.hydroshare.org/resource/77114d4dfdfd4dd39e0e1d99165f27b3

Beschreibung: During the last 20 years some very hot and dry summers affected Europe, resulting in regionally record‐breaking high temperature or low precipitation values. Long‐term changes of such extremely hot and dry summers are of great relevance for our society, as they are connected with manifold negative impacts on human society, natural ecosystems, and diverse economic sectors. Long‐term variations in drought and five record drought summer half years are studied based on 63 stations across Europe with high‐quality precipitation and temperature time series spanning the period 1901–2018. Eight drought indices are deployed to analyse drought intensity, frequency, and duration; four of them purely precipitation‐based and four integrating potential evapotranspiration in the computation. Additionally, three heavy precipitation indices and simultaneous increases in drought and heavy precipitation are studied. The five driest summer half years over Europe are identified (1947, 2018, 2003, 1921, and 1911). They are analysed by aggregating eight drought indices into the aggregated drought evaluation index (ADE) for five subregions. The ADE shows increasing summer drought conditions over most of Europe, except for some stations in northern Europe. The increase in drought conditions during the warm part of the year is particularly pronounced for indices integrating evapotranspiration in their definition. At the same time, the intensity of heavy precipitation events shows a positive trend, as well as an increased contribution to total precipitation. Several stations in central Europe show simultaneously increasing drought conditions and increasing heavy precipitation events. This increases the risks connected with precipitation extremes.

Beschreibung: Drought and heavy precipitation trends are studied for selected stations with long time series. Both extreme events are related to specific impacts on different economic sectors and thus society. Stations that simultaneously show increasing trends in drought and heavy precipitation mainly occur in central Europe. This indicates a probably higher exposure to these risks in central Europe as well as a demand for broader adaptation options in this region.

Beschreibung: Enhancing the resilience of complex social‐ecological systems (SES) to climate change requires transformative changes. Yet, there are knowledge gaps on how best to achieve transformation. In this study, we present an approach for assessing governance performance in SES and identifying leverage points to ultimately enhance climate resilience. The approach combines three different methods including a capital approach framework, fuzzy cognitive mapping, and a leverage points analysis. Using a coastal case‐study in Algoa Bay, South Africa, the performance of governance processes contributing to different forms of capital is assessed. Subsequently, leverage points ‐ where a small shift may lead to transformative changes in the system as a whole ‐ are identified based on measures of centrality and performance. Results suggest that a range of leverage points can improve governance performance and therefore climate resilience in the case‐study. Leverage points include improving (a) support from the provincial government; (b) priority given to climate change in the integrated development plan; (c) frequency of collaborations; (d) participation in the implementation of climate action plans; (e) allocation of funding to climate change actions; (f) the overall level of preparedness in terms of staff with relevant expertise; (g) public awareness and understanding of climate change. The approach can also be used to analyze and model the relations and interactions between capitals. The study advances methodological and theoretical knowledge on the identification of leverage points for enabling transformations toward climate resilience and broader sustainability goals in SES.

Beschreibung: Plain Language Summary: Climate change has severe impacts on both people and nature. Enhancing the ability to persist and adapt to climate change requires transformative governance of social‐ecological systems. However, more knowledge is required on how to enable such transformations. In this paper, we present an approach to measure the performance of different governance processes, such as decisions and actions for climate change adaptation made by public and governmental organizations. The approach aims to identify key processes, where a small intervention may improve overall performance for climate change adaptation, and therefore transformation. We apply the approach in a real‐world example in Algoa Bay, South Africa. Results suggest that different processes in the case‐study can be changed in order to enhance the ability to persist and adapt to climate change. This includes seven actions: (a) more support from governmental organizations; (b) greater priority given to climate change in relevant policies; (c) increasing the frequency of interactions between organizations; (d) enhancing the participation in the implementation of climate action plans; (e) better allocation of funding to climate change actions; (f) training staff within organizations to enhance their climate expertise; (g) improving public awareness and understanding of climate change.

Beschreibung: Key Points: The study presents an approach for assessing governance performance and identifying leverage points in social‐ecological systems. The approach combines three different methods: a capital approach framework, fuzzy cognitive mapping, and a leverage points analysis. The study advances methodological and theoretical knowledge on how to operationalize transformation toward climate resilience.

Beschreibung: Helmholtz‐Zentrum Hereon

Beschreibung: Western Indian Ocean Marine Science Association http://dx.doi.org/10.13039/501100009106

Beschreibung: https://doi.org/10.6084/m9.figshare.20732788

Beschreibung: The diversity of El Niño events is commonly described by two distinct flavors, the Eastern Pacific (EP) and Central Pacific (CP) type. While the remote impacts, that is, teleconnections, of EP and CP events have been studied for different regions individually, a global picture of their structure is still lacking. Here, we use Forman‐Ricci curvature applied on climate networks constructed from surface air temperature data to distinguish regional links from teleconnections. Our results confirm that both El Niño types influence the teleconnection patterns, however, with different spatial manifestations. Our analysis suggests that EP El Niños alter the general circulation which changes the teleconnection structure to primarily tropical teleconnections. In contrast, the teleconnection pattern of CP El Niños show only subtle changes to normal conditions. Moreover, this work identifies the dynamics of the Eastern Pacific as a proxy for the remote impact of both El Niño types.

Beschreibung: Plain Language Summary: El Niño events, characterized by anomalous sea surface temperatures (SSTs) in the Tropical Pacific, come in two flavors; Eastern Pacific (EP) and Central Pacific (CP) types, depending on the longitudinal location of the strongest SST anomalies. Their remote impacts, known as teleconnections, differ. Although there are many studies investigating teleconnections of EP and CP events for individual target regions, a global analysis of the spatial distribution of their teleconnections is still lacking. In this study, we use the theory of complex networks to study EP and CP El Niño teleconnections. We construct “climate networks” from global surface air temperature data and use the notion of “curvature” of a network link to uncover their spatial organization. We show that the most negatively curved links highlight important teleconnection patterns that differ depending on the El Niño type. EP events change the teleconnection structure to the tropics while CP and Normal year conditions reveal teleconnections to all latitudes. Interestingly, the Central Pacific does not show many teleconnections, even during CP El Niño events which we attribute to the varying location of warm water anomalies in the Central Pacific. The Eastern Pacific changes more consistently allowing identifying remote impacts of both El Niños types.

Beschreibung: Key Points: Ricci curvature of boreal winter climate networks reveals long‐range teleconnection structure. Eastern Pacific (EP) El Niños show primarily teleconnections in tropical while Central Pacific El Niños teleconnections on all latitudes. The EP contains robust teleconnections for both El Niño types.

Beschreibung: Deutsche Forschungsgemeinschaft, DFG http://dx.doi.org/10.13039/501100001659

Beschreibung: research

Beschreibung: The novel Aeolus satellite, which carries the first Doppler wind lidar providing profiles of horizontal line‐of‐sight (HLOS) winds, addresses a significant gap in direct wind observations in the global observing system. The gap is particularly critical in the tropical upper troposphere and lower stratosphere (UTLS). This article validates the Aeolus Rayleigh–clear wind product and short‐range forecasts of the European Centre for Medium‐Range Weather Forecasts (ECMWF) with highly accurate winds from the Loon super pressure balloon network at altitudes between 16 and 20 km. Data from 229 individual balloon flights are analysed, applying a collocation criterion of 2 hr and 200 km. The comparison of Aeolus and Loon data shows systematic and random errors of -0.31 and 6.37 m·s〈sup〉-1〈/sup〉, respectively, for the Aeolus Rayleigh–clear winds. The horizontal representativeness error of Aeolus HLOS winds (nearly the zonal wind component) in the UTLS ranges from 0.6–1.1 m·s〈sup〉-1〈/sup〉 depending on the altitude. The comparison of Aeolus and Loon datasets against ECMWF model forecasts suggests that the model systematically underestimates the HLOS winds in the tropical UTLS by about 1 m·s〈sup〉-1〈/sup〉. While Aeolus winds are currently considered as point winds by the ECMWF data assimilation system, the results of the present study demonstrate the need for a more realistic HLOS wind observation operator for assimilating Aeolus winds.

Beschreibung: El Niño–Southern Oscillation (ENSO) is one of the most important modes of climate variability on interannual timescales. We aim to find out whether a change in ENSO frequency can be predicted for the nearer future. We analyse the unforced pre‐industrial control run and the forced 1%/year CO〈sub〉2〈/sub〉 increase run for an ensemble of 43 general circulation models that participated in the Coupled Model Intercomparison Project Phase 6 (CMIP6). We assume that the uncertainty of ENSO frequency trend estimates from an ensemble is caused by apparent trends as well as model differences. The part of the uncertainty caused by apparent trends is estimated from the pre‐industrial control simulations. As a measure for ENSO frequency, we use the number of El Niño‐ and La Niña‐like months in a moving 30‐year time window. Its linear decadal trend is calculated for every member. The multimember mean of the trend for both experiments is less than 0.7 events per decade. Given that the standard error is of the same order of magnitude, we consider this a negligible trend. The uncertainties are large in both experiments and we can attribute most of the intermember variability to apparent trends due to natural variability rather than different model reactions to CO〈sub〉2〈/sub〉 forcing. This means that the impact of intermodel differences might have been overstated in previous studies. Apparent trends make it very difficult to make reliable predictions of changes in ENSO frequency based on 120‐year time series.

Beschreibung: The 1pctCO2 and piControl ensembles from CMIP6 are analysed for 43 models with a focus on changes in ENSO frequency. We find that most of the intermember variability can be attributed to natural variability instead of model differences. Therefore, the uncertainty can only marginally be reduced and it is very difficult to reliably predict changes in ENSO frequency on a timescale of 150 years.

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: https://doi.org/10.5281/zenodo.6841964

Beschreibung: A new version of the AWI Coupled Prediction System is developed based on the Alfred Wegener Institute Climate Model v3.0. Both the ocean and the atmosphere models are upgraded or replaced, reducing the computation time by a factor of 5 at a given resolution. This allowed us to increase the ensemble size from 12 to 30, maintaining a similar resolution in both model components. The online coupled data assimilation scheme now additionally utilizes sea‐surface salinity and sea‐level anomaly as well as temperature and salinity profile observations. Results from the data assimilation demonstrate that the sea‐ice and ocean states are reasonably constrained. In particular, the temperature and salinity profile assimilation has mitigated systematic errors in the deeper ocean, although issues remain over polar regions where strong atmosphere‐ocean‐ice interaction occurs. One‐year‐long sea‐ice forecasts initialized on 1 January, 1 April, 1 July and 1 October from 2003 to 2019 are described. To correct systematic forecast errors, sea‐ice concentration from 2011 to 2019 is calibrated by trend‐adjusted quantile mapping using the preceding forecasts from 2003 to 2010. The sea‐ice edge raw forecast skill is within the range of operational global subseasonal‐to‐seasonal forecast systems, outperforming a climatological benchmark for about 2 weeks in the Arctic and about 3 weeks in the Antarctic. The calibration is much more effective in the Arctic: Calibrated sea‐ice edge forecasts outperform climatology for about 45 days in the Arctic but only 27 days in the Antarctic. Both the raw and the calibrated forecast skill exhibit strong seasonal variations.

Beschreibung: Plain Language Summary: Ocean data sparseness and systematic model errors pose problems for the initialization of coupled seasonal forecasts, especially in polar regions. Our global forecast system follows a seamless approach with refined ocean resolution in the Arctic. The new version presented here features higher computational efficiency and utilizes more ocean and sea‐ice observations. Ice‐edge forecasts outperform a climatological benchmark for about 1 month, comparable to established systems.

Beschreibung: Key Points: We describe an upgrade of the AWI Coupled Prediction System with new ocean and atmosphere models and more observations assimilated. Independent evaluations show advances in the new version on the analysis of the sea‐ice and ocean states against the old one. Calibrated sea‐ice edge forecasts outperform a climatological benchmark for around 1 month in both hemispheres.

Beschreibung: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809

Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347

Beschreibung: Deutsche Forschungsgemeinschaft

Beschreibung: https://doi.org/10.5281/zenodo.6335383

Beschreibung: https://github.com/FESOM/fesom2/releases/tag/AWI-CM3_v3.0

Beschreibung: https://doi.org/10.5281/zenodo.6335498

Beschreibung: https://oasis.cerfacs.fr/en/

Beschreibung: https://doi.org/10.5281/zenodo.4905653

Beschreibung: http://forge.ipsl.jussieu.fr/ioserver

Beschreibung: https://doi.org/10.5281/zenodo.6335474

Beschreibung: http://pdaf.awi.de/

Beschreibung: https://doi.org/10.5281/zenodo.6481116

Beschreibung: Using the global and coupled ICOsahedral Nonhydrostatic model with the Sapphire configuration (ICON‐S) and a grid spacing of 5 km, we describe seasonal and diurnal features of the tropical rainbelt and assess the limits of ICON‐S in representing tropical precipitation. ICON‐S shows that, by resolving meso‐beta scale process, the rainbelt structure and its seasonality (zonal and meridional migration and enlargement) is reproduced, with better performance over land than over ocean and with a very high degree of agreement to observations. ICON‐S especially struggles in capturing the seasonal features of the tropical rainbelt over the oceans of the Eastern Hemisphere, an issue associated with a cold sea surface temperature (SST) bias at the equator. ICON‐S also shows that a perfect representation of the diurnal cycle of precipitation over land is not a requirement to capture the seasonal features of the rainbelt over land, while over the ocean, 5 km is sufficient to adequately represent the diurnal cycle of precipitation.

Beschreibung: Plain Language Summary: Over the tropics, precipitation falls in distinct bands, that span the circumference of the Earth. These bands migrate from the Northern to the Southern Hemisphere and vice versa following the seasonal migration of the sun. Their center of mass also varies east‐west, as well as their area. Where rain ends up falling is of key importance but conventional climate models relying on statistical approaches to simulate convection cannot represent these characteristics. Here we report on the results of simulations on a global domain and, to our knowledge, for the first time integrated with an atmosphere‐ocean coupled over a full seasonal cycle and with a grid spacing fine enough to explicitly represent convection and Mesoscale Ocean eddies. We show that such simulations can reproduce many aspects of the seasonal migration of the rainbelt over land. For instance, the north‐south and east‐west migration of the rainbelt as well as its expansion during the summer season are well captured. This is also the case for the rainbelt in the eastern Pacific and the Atlantic, but not in the Eastern Hemisphere, where the poor representation of the sea surface temperature pattern distorts the representation of the rainbelt and its seasonal characteristics.

Beschreibung: Key Points: In one year of simulation, the ICOsahedral Nonhydrostatic model with the Sapphire configuration (ICON‐S) reproduces the seasonal features of the tropical rainbelt over land with high agreement with observations. In the eastern Pacific and Atlantic, the seasonal structure and movement of the rainbelt are also reproduced by ICON‐S. Biases in sea surface temperature explain the struggles of ICON‐S in simulating the oceanic rainbelt of the Eastern Hemisphere.

Beschreibung: Hans‐Ertel Centre for Weather Research

Beschreibung: European Union's Horizon 2020

Beschreibung: DKRZ compute time

Beschreibung: https://doi.org/10.17617/3.1XTSR6

Beschreibung: https://mpimet.mpg.de/en/science/modeling-with-icon/code-availability

Beschreibung: https://doi.org/10.5067/GPM/IMERG/3B-HH/06

Beschreibung: https://www.cen.uni-hamburg.de/en/icdc/data/atmosphere/imerg-precipitation-amount.html

Beschreibung: https://www.cen.uni-hamburg.de/en/icdc/data/ocean/hadisst1.html

Beschreibung: https://hdl.handle.net/21.11116/0000-000B-4BAE-E

Beschreibung: This work focuses on the potential of a network of Doppler lidars for the improvement of short‐term forecasts of low‐level wind. For the impact assessment, we developed a new methodology that is based on ensemble sensitivity analysis (ESA). In contrast to preceding network design studies using ESA, we calculate the explicit sensitivity including the inverse of the background covariance B matrix to account directly for the localization scale of the assimilation system. The new method is applied to a pre‐existing convective‐scale 1,000‐member ensemble simulation to mitigate effects of spurious correlations. We evaluate relative changes in the variance of a forecast metric, that is, the low‐level wind components averaged over the Rhein–Ruhr metropolitan area in Germany. This setup allows us to compare the relative variance change associated with the assimilation of hypothetical observations from a Doppler wind lidar with respect to the assimilation of surface‐wind observations only. Furthermore, we assess sensitivities of derived variance changes to a number of settings, namely observation errors, localization length scale, regularization factor, number of instruments in the network, and their location, as well as data availability of the lidar measurements. Our results demonstrate that a network of 20–30 Doppler lidars leads to a considerable variance reduction of the forecast metric chosen. On average, an additional network of 25 Doppler lidars can reduce the 1–3 hr forecast error by a factor of 1.6–3.3 with respect to 10‐m wind observations only. The results provide the basis for designing an operational network of Doppler lidars for the improvement of short‐term low‐level wind forecasts that could be especially valuable for the renewable energy sector.

Beschreibung: This study presents the potential of a Doppler lidar network to improve short‐term low‐level wind forecasts. The approach used in this study does not require real observations and can provide valuable information for designing an operational network. The study is based on a convective‐scale 1,000‐member ensemble simulation over Germany. The results show that Doppler lidars lead to considerable variance reduction and should be considered for future observational networks.

Beschreibung: Hans‐Ertel‐Centre for Weather Research funded by the German Federal Ministry for Transportation and Digital Infrastructure

Beschreibung: https://doi.org/10.5281/zenodo.6331758

Beschreibung: Climate hazards associated with compound events (CEs) have lately received increasing attention over South America (SA) due to their potential risks and amplification of impacts. This work addressed the evaluation of different temperature‐ and precipitation‐based CE in SA considering the CORDEX‐CORE ensemble of regional climate models (RCMs) and their driving earth system models (ESMs) in the reference period 1981–2010 and the late 21st century (2070–2099), for the Representative Concentration Pathways (RCPs) 2.6 and 8.5 scenarios. The assessment focused on model performance for the individual events—heatwaves (HWs), Extreme rainfall (ER) days, and dry‐spells (DSs)—and their compound occurrence in terms of climatological frequency and duration. The spatial patterns of individual events were adequately reproduced by the RCMs, evidencing general overestimations in extreme precipitation intensities. In terms of CE, the frequencies of coincident HWs and DSs (sequential DSs and ER) were remarkable over central‐eastern Brazil and southern SA (southeastern SA). The main features of CE were generally well‐simulated by the RCMs, although they presented regional differences such as an underestimation of the maximum frequencies of these two CE in northeastern Brazil and southeastern SA, respectively. The high‐resolution information was generally in line with the larger‐scale driving ESMs. The climate change signal analysis generally showed robust future increases in CE frequency and duration in different areas of SA, as for coincident HWs and DSs (sequential DSs and ER) over northern SA and southern Brazil (southeastern SA). This was mostly consistent among the RCMs ensemble and notably strengthened in the worst‐case scenario (RCP 8.5).

Beschreibung: Key Points: Coincident heatwaves and dry‐spells (DSs) and sequential DSs and extreme rainfall are remarkable compound events (CEs) over South America. Regional climate models can reproduce the frequency and duration of CEs, but with some regional differences. CEs are generally expected to be more frequent in the late 21st century, particularly in the Representative Concentration Pathway 8.5 scenario.

Beschreibung: UBA Secretaría de Ciencia y Técnica, Universidad de Buenos Aires http://dx.doi.org/10.13039/501100010253

Beschreibung: Argentinian ANPCyT

Beschreibung: https://www.ecmwf.int/en/forecasts/datasets/reanalysis-datasets/era5

Beschreibung: https://esgf-data.dkrz.de/projects/esgf-dkrz/

Beschreibung: https://psl.noaa.gov/data/gridded/

Beschreibung: Geometric 3D models are a very efficient tool to visualize geological units and structural features that have been presented before just in two dimensions on maps or cross-sections. Most of the information of 3D models is presented as 3D views, virtual wells or horizontal or vertical cross-sections. However, are there further options to transfer as much as possible of the complex information of a 3D model in an adequate way to the user? Is it useful and promising to analyse 3D objects like surfaces or volumes in GIS software? In our investigation we performed a GIS based analysis of an existing geotechnical-geological 3D model of periglacial sediments. The two steps were multiple raster calculations to create geotechnical maps and a digital analysis of surface parameters based on geomorphological techniques and statistics. The investigation area is located in southern Lower Saxony and covers the city of Goettingen and surrounding regions within the valley of the river Leine. The valley is filled by unconsolidated, periglacial sediments of Quaternary age with a variable thickness ranging from 1 to 70 m. The analysed 3D model was constructed with GoCAD in a former project (Nix et al. 2009). The model is based on a heterogenous dataset comprising well data, thematic maps, and outcrop descriptions. Finally, the surfaces and volumes of the following units were modelled, with a special focus on their different geotechnical properties: (1) anthropogenic material, (2) floodplain and slope deposits, (3) freshwater limestone, peat and organic clay, (4) loess, displaced loess, and loess loam, (5) fluvial gravel, (6) outwash fan material, (7) solifluction material, (8) mixed, hetereougenous fillings of subrosion sinks and (9) the surface of the underlying hardrocks. Each top and bottom surface of the Gocad volumes was exported as raster file with additional information stored in an associated attribute table. In ArcGIS various geoprocessing tools were used to calculate and analyse these rasters and to develope thematic geotechnical and geological maps. The geomorphological analysis was subdivided in several steps. Firstly, the surfaces were described visually, concerning their outline, shape and distribution, as well as superficial structures like distinct edges, holes, channels. Secondarily, descriptive statistic parameters of thickness, area and elevation of each surface were calculated. Thirdly, geoprocessing tools of the Spatial Analyst were performed on each surface. Finally, several surfaces were combined to analyse them together, calculating ratios and overlay combinations. Seven thematical geoengineering and geological maps were created, each of them presenting one portion of the three-dimensional dataset: Map of the stratigraphy and depth of the Quaternary base, Map of the thickness of the Quaternary sediments, Distribution map of model units 1 m below ground level, Distribution map of model units 2 m below ground level, Maps of types of different foundation soils, Distribution map of sediments with low loading capacity and Map of distribution and quality of the wells. While the map creation focused on the geotechnical aspects of the model, the applied geomorphological analysis revealed various parameters and values that are related to the geological formation of the model units. Despite the complex dataset represented by the analysed 3D model, thematical information could be transfered into 2D as thematic maps. Some geological characteristics and parameters of the model units were extracted by the descriptive and GIS-based analysis. References Nix, T., Wagner, B., Lange, T. , Fritz, J., Sauter, M. (2009): 3D-Baugrundmodell der quartären Sedimente des Leinetals bei Göttingen. – 17. Tagung für Ingenieurgeologie, S. 223-227, Zittau

Beschreibung: poster

Beschreibung: The mineralogy, chemical composition, and physical properties of cratonic mantle eclogites with oceanic crustal protoliths can be modified by secondary processes involving interaction with fluids and melts, generated in various slab lithologies upon subduction (auto‐metasomatism) or mantle metasomatism after emplacement into the cratonic lithosphere. Here we combine new and published data to isolate these signatures and evaluate their effects on the chemical and physical properties of eclogite. Mantle metasomatism involving kimberlite‐like, ultramafic carbonated melts (UM carbonated melts) is ubiquitous though not pervasive, and affected between ~20% and 40% of the eclogite population at the various localities investigated here, predominantly at ~60–150 km depth, overlapping cratonic midlithospheric seismic discontinuities. Its hallmarks include lower jadeite component in clinopyroxene and grossular component in garnet, an increase in bulk‐rock MgO ± SiO2, and decrease in FeO and Al2O3 contents, and LREE‐enrichment accompanied by higher Sr, Pb, Th, U, and in part Zr and Nb, as well as lower Li, Cu ± Zn. This is mediated by addition of a high‐temperature pyroxene from a UM carbonated melt, followed by redistribution of this component into garnet and clinopyroxene. As clinopyroxene‐garnet trace‐element distribution coefficients increase with decreasing garnet grossular component, clinopyroxene is the main carrier of the metasomatic signatures. UM carbonated melt‐metasomatism at 〉130–150 km has destroyed the diamond inventory at some localities. These mineralogical and chemical changes contribute to low densities, with implications for eclogite gravitational stability, but negligible changes in shear‐wave velocities, and, if accompanied by H2O‐enrichment, will enhance electrical conductivities compared to unenriched eclogites.

Beschreibung: Plain Language Summary: Oceanic crust formed at spreading ridges is recycled in subduction zones and undergoes metamorphism to eclogite. Some of this material is captured in the overlying lithospheric mantle, where it is exhumed by passing magmas. Having formed in spreading ridges, these eclogites have proven invaluable archives for the onset of plate tectonics, for the construction of cratons during subduction/collision, as probes of the convecting mantle from which their precursors formed, and as generators of heterogeneity upon recycling into Earth's convecting mantle. During subduction and until exhumation, interaction with fluids and melts (called metasomatism) can change the mineralogy, chemical composition, and physical properties of mantle eclogites, complicating their interpretation, but a comprehensive study of these effects is lacking so far. We investigated mantle eclogites from ancient continents (cratons) around the globe in order to define hallmarks of metasomatism by subduction‐related fluids and small‐volume ultramafic carbonated mantle melts. We find that the latter is pervasive and occurs predominantly at midlithospheric depths where seismic discontinuities are detected, typically causing diamond destruction and a reduction in density. This has consequences for their gravitational stability and for the interpretation of shearwave velocities in cratons.

Beschreibung: Key Points: Exploration of metasomatic effects during subduction of ancient oceanic crust and after its emplacement into cratonic lithospheric mantle. Metasomatism by kimberlite‐like ultramafic melt affected between 20% and 40% of mantle eclogite suites worldwide, mostly at 2–5 GPa. Metasomatism lowers FeO, hence density in eclogite; no significant effect on shearwave velocities.

Beschreibung: German Research Foundation http://dx.doi.org/10.13039/501100001659

Beschreibung: National Research Foundation (NRF) http://dx.doi.org/10.13039/501100001321

Beschreibung: Wilhelm and Else Heraeus Foundation http://dx.doi.org/10.13039/501100011618

Beschreibung: Deutsche Forschungsgemeinschaft (DFG, INST

Beschreibung: research

Beschreibung: Pyrroloquinoline quinone (PQQ) is an important cofactor of calcium‐ and lanthanide‐dependent alcohol dehydrogenases, and has been known for over 30 years. Crystal structures of Ca–MDH enzymes (MDH is methanol dehydrogenase) have been known for some time; however, crystal structures of PQQ with biorelevant metal ions have been lacking in the literature for decades. We report here the first crystal structure analysis of a Ca–PQQ complex outside the protein environment, namely, poly[[undecaaquabis(μ‐4,5‐dioxo‐4,5‐dihydro‐1H‐pyrrolo[2,3‐f]quinoline‐2,7,9‐tricarboxylato)tricalcium(II)] dihydrate], {[Ca3(C14H3N2O8)2(H2O)11]·2H2O}n. The complex crystallized as Ca3PQQ2·13H2O with Ca2+ in three different positions and PQQ3−, including an extensive hydrogen‐bond network. Similarities and differences to the recently reported structure with biorelevant europium (Eu2PQQ2) are discussed.

Beschreibung: Pyrroloquinoline quinone (PQQ) is an important cofactor of calcium‐ and lanthanide‐dependent alcohol dehydrogenases. The crystal structure of a Ca–PQQ complex (Ca3PQQ2·13H2O) is reported for the first time outside a protein environment. image

Beschreibung: research

Beschreibung: In Structural Geology, many projects start with intensive field-based data acquisition campaigns, which might be performed in quite different types of natural or artificial outcrops. For some years, this field work has been substantially influenced and transformed by various close-range sensing techniques that allow the field geologist to create a digital outcrop model (DOM) and to take along plenty of geometrical and spectral information about the outcropping rocks. In general, DOMs can be utilized for outcrop visualization, documentation, manual outcrop analysis (“point-picking”), extraction of spectral data and/or semi-automatic extraction of geometric data. Within a structural investigation DOMs might be deployed for fold analysis, fault analysis, extraction of fracture networks, fracture roughness estimation, detection of neotectonic activities or digitization of geological features for 3D-models of various scales resulting in a large number of analyzing techniques. Latter might be carried out on point clouds or meshes (with or without spectral information) and may differ in pre-processing and processing steps as well as in software solution. Therefore, the analyzing structural geologist faces various tools, data formats, file types, operations and outcomes. Our investigation focus on the compilation of useful, transparent, sustainable and comparable workflows or “pipelines”, which can be executed by open-source/open-access solutions.

Beschreibung: poster

Beschreibung: Quantitative fold structure analyses at different scales are essential for deducing deformation mechanisms and the reconstruction of the deformation history of orogens. However, not only the field surveying of fold structures, especially in view of their quantification in three dimensions with the classical tools as measuring tape, grid mapping with measuring tapes, geological compass, field book and camera is a time consuming and laborious job, but also the construction of a georeferenced 3D-model of fold structures based on classical data. Another crucial aspect of the classical field surveying of folds is the limitation by poor outcrop conditions. Reasons might be restricted or no accessibility due to high outcrop walls, water or fences, limited visibility because of vegetation, difficult measurability due to very smooth walls or complexity as a result of irregular outcrop walls or distant outcrops. Furthermore, inappropriate oriented outcrop surfaces in respect to the fold geometry can make a survey even worse. Over the past years modern 3D surveying techniques like terrestrial Lidar and digital photogrammetry became progressively affordable for geological field work and now start to complement or replace traditional methods. We started to utilize these techniques on fold structure surveying and to apply quantitative fold structure analysis on different outcrop settings in Central Germany. Different workflows were developed and tested to optimize data conversion, handling and representation. We applied a laser scanner and a single lens reflex camera, complemented by a differential GPS device and laser tachymeter. Data conversion, correction and analysis were done by means of different free as well as commercial software packages. To test different outcrop situations, different quarries, salt mines and steep cliffs, exposing from single fold to complex folds in limestone, greywacke, cherts, rock salt or potassium salt, were selected. As a result, exact 3D point clouds of all exposed folds could be generated by the use of both techniques. The resultant point clouds are suited as excellent visualisation objects as well as base for accurate geometrical measurements in the range of mm or cm of single and complex folds. In addition, the point clouds serve as input dataset for the construction of detailed geological 3D models comprising punctual, linear and plane fold elements. In summary, terrestrial Lidar and digital photogrammetry are excellent field techniques to survey and document exposed folds in the range of few meters to tens of meters, especially under poor outcrop conditions. Different fold sections can now easily be correlated in 3D space to construct complete fold structures with their 3D-fold geometry. Certain fold elements, e.g. axial planes, can be reconstructed much faster and much more accurate compared to the classical approach. The only limiting factor are the very large datasets and the processing power. As next steps, we seek (1) to involve drones for completing data sets from inaccessible areas and perspectives and (2) to incorporate 3D-microfabric analysis data in the fold models as e.g. grain shape an crystallographic preferred orientations to better understand stain paths and deformation mechanisms.

Beschreibung: poster

Beschreibung: Under certain conditions, ocean surface gravity waves (SGW) interact with the seafloor underneath to trigger relatively faint but measurable seismic waves known as ocean microseisms. Cyclonic storms (e.g. hurricanes, typhoons) wandering over the ocean are major (non-stationary) sources of the former, thus opening the possibility of tracking and studying cyclones by means of their corresponding microseims. For this purpose, we identified storm-related microseisms hidden in the ambient seismic wavefield via array processing. Polarization beamforming, a robust and well-known technique is implemented. The analyses hinge on surface waves (Love and Rayleigh) which, in contrast to P-waves, are stronger but only constrain direction of arrival (without source remoteness). We use a few land-based virtual seismic arrays surrounding the North Atlantic to investigate the signatures of major hurricanes in the microseismic band (0.05-0.16 Hz), in a joint attempt to continuously triangulate their tracks. Our findings show that storm microseisms are intermittently excited with modulated amplitude at localized oceanic regions, particularly over the shallow continental shelves and slopes, having maximum amplitudes virtually independent of storm category. In most cases no detection was possible over deep oceanic regions, nor at distant arrays. Additionally, the rear quadrants and trailing swells of the cyclone provide the optimum SGW spectrum for the generation of microseisms, often shifted more than 500 km off the "eye". As a result of the aforementioned and added to the strong attenuation of storm microseisms, the inversion of tracks or physical properties of storms using a few far-field arrays is discontinuous in most cases, being reliable only if benchmark atmospheric and/or oceanic data is available for comparison. Even if challenging due to the complexity of the coupled phenomena responsible for microseisms, the inversion of site properties, such as bathymetric parameters (e.g. depth, seabed geomorphology), near- bottom geology or SGW spectrum might be possible if storms are treated as natural sources in time-lapse ambient noise investigations. This will likely require near-field (land and underwater) observations using optimal arrays or dense, widespread sensor networks. Improved detection and understanding of ocean microseisms carries a great potential to contribute to mechanically coupled atmosphere-ocean-earth models.

Beschreibung: Universität Hamburg

Beschreibung: poster

Beschreibung: The transient climate response (TCR) is 20% higher in the Alfred Wegener Institute Climate Model (AWI‐CM) compared to the Max Planck Institute Earth System Model (MPI‐ESM) whereas the equilibrium climate sensitivity (ECS) is by up to 10% higher in AWI‐CM. These results are largely independent of the two considered model resolutions for each model. The two coupled CMIP6 models share the same atmosphere‐land component ECHAM6.3 developed at the Max Planck Institute for Meteorology (MPI‐M). However, ECHAM6.3 is coupled to two different ocean models, namely the MPIOM sea ice‐ocean model developed at MPI‐M and the FESOM sea ice‐ocean model developed at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). A reason for the different TCR is related to ocean heat uptake in response to greenhouse gas forcing. Specifically, AWI‐CM simulations show stronger surface heating than MPI‐ESM simulations while the latter accumulate more heat in the deeper ocean. The vertically integrated ocean heat content is increasing slower in AWI‐CM model configurations compared to MPI‐ESM model configurations in the high latitudes. Weaker vertical mixing in AWI‐CM model configurations compared to MPI‐ESM model configurations seems to be key for these differences. The strongest difference in vertical ocean mixing occurs inside the Weddell and Ross Gyres and the northern North Atlantic. Over the North Atlantic, these differences materialize in a lack of a warming hole in AWI‐CM model configurations and the presence of a warming hole in MPI‐ESM model configurations. All these differences occur largely independent of the considered model resolutions.

Beschreibung: Plain Language Summary: The transient climate response (TCR) describes how strongly near‐surface temperatures warm in response to gradually increasing greenhouse‐gas levels. Here we investigate the role of the ocean which takes up heat and thereby delays the surface warming. Two models of the Coupled Model Intercomparison Project Phase 6 (CMIP6), the Alfred Wegener Institute Climate Model (AWI‐CM) and the Max Planck Institute Earth System Model (MPI‐ESM), which use the same atmosphere model but different ocean models are selected for this study. In AWI‐CM the upper ocean layers heat faster than in MPI‐ESM, while the opposite is true for the deep ocean. As a consequence, the TCR is 20% stronger in AWI‐CM compared to MPI‐ESM. We find that weaker vertical ocean mixing in AWI‐CM compared to MPI‐ESM, especially over the northern North Atlantic and the Weddell and Ross Gyres, is key for these differences. Our findings corroborate the importance of realistic ocean mixing in climate models when it comes to getting the strength and timing of climate change right.

Beschreibung: Key Points: The transient climate response in two coupled models with the same atmosphere but different ocean components differs by 20%. The upper (deeper) ocean heats faster (slower) in AWI‐CM compared to MPI‐ESM, independent of model resolution. Vertical mixing in the northern North Atlantic and the Weddell and Ross Gyres appears to be key for these differences.

Beschreibung: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347

Beschreibung: German Climate Computing Centre (DKRZ)

Beschreibung: Federal Ministry of Education and Research of Germany

Beschreibung: Helmholtz Association http://dx.doi.org/10.13039/501100009318

Beschreibung: https://esgf-data.dkrz.de/projects/cmip6-dkrz/

Beschreibung: In the hyperarid Atacama Desert in northern Chile, rare precipitation events can leave long‐lasting geomorphological traces and have strong impacts on biota. While moisture conveyor belts (MCBs) and atmospheric rivers (ARs) have been associated with extreme precipitation in semiarid regions, their role for the Atacama Desert has not been previously investigated. This study reveals that about four MCBs per year make landfall in the Atacama Desert. According to simulated precipitation, 40–80% of the total precipitation between the coast and the Andean foothills is associated with MCBs. A case study reveals an elevated moisture transport decoupled from the maritime boundary layer, which is generalized by a composite analysis. Back trajectories reveal the Amazon Basin as the main source of moisture. MCB landfall times are derived from the AR catalog by Guan and Waliser (2015), https://doi.org/10.1002/2015jd024257. Implications of the results on paleoclimate reconstructions are discussed.

Beschreibung: Plain Language Summary: In the extremely dry Atacama Desert in northern Chile, rare rain events can trigger landscape alterations and have strong impacts on various life forms. Traces of such events are conserved within the desert soil over long time periods throughout the enduring dryness. Such traces constitute climate archives, which can be excavated and explored. Understanding particular conditions, which lead to extreme precipitation events is necessary to interpret such archives, reconstruct climate history, and explore thresholds of life at the dry limit. In this study, the role of a weather phenomenon called moisture conveyor belt (MCB) is quantified for the first time for the Atacama Desert. It is demonstrated that depending on region, 40–80% of the total rainfall is associated with these phenomena. In contrast to atmospheric river characteristics reported for midlatitudes, a unique vertical structure with an elevated moisture transport independent of the near‐surface layer is discovered here. Even though the identified MCBs approach the Atacama Desert from northwesterly directions across the Pacific Ocean, the associated moisture mostly originates from the Amazon Basin.

Beschreibung: Key Points: For most parts of the Atacama Desert, more than half of the total precipitation is related to moisture conveyor belts (MCBs). In contrast to midlatitudes, main moisture transport takes place in mid‐tropospheric layers decoupled from the maritime boundary layer. The main origin of the MCB‐related moisture is found to be the Amazon Basin.

Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659

Beschreibung: https://www.crc1211db.uni-koeln.de/search/view.php?dataID=38

Beschreibung: http://www.cr2.cl/datos-de-precipitacion/

Beschreibung: http://explorador.cr2.cl/

Beschreibung: Large artificial lakes and reservoirs affect the meteorological regime of the shore area and the local climate takes on a number of new features that were previously absent. This work focuses on the weather impact of the Alqueva reservoir, the largest artificial lake in Western Europe. An extensive set of numerical simulations using Meso‐NH mesoscale atmospheric model coupled with FLake (Freshwater Lake) scheme was carried out. The simulations covered a 12‐month period that was chosen to compose a so‐called Typical Meteorological Year. This artificial time period is meant to represent the typical meteorological conditions in the region and the model results are used to assess the changes in the local climate. To evaluate the raw impact of the reservoir, two different scenarios of simulations were compared: (A) with the reservoir as it exists nowadays and (B) without the reservoir using the older surface dataset. The results show decrease of air temperature during daytime (10–9°C) and nighttime increase (up to 10°C). In nearest towns, daily maximum temperature decreased and daily minimum temperature increased, which refers to milder weather conditions. Alqueva mainly showed suppression in fog formation in the nearby area. Local breeze regime was studied and monthly lake/land breezes were described.

Beschreibung: Large lakes and artificial reservoirs can affect the meteorological regime of their coastal areas and impact the local climate. This work focuses on the weather impact of the Alqueva reservoir, the largest artificial lake in Western Europe, studied on the basis of mesoscale atmospheric modelling data over the 12‐month period composed in a typical meteorological year for the region of interest.

Beschreibung: ALOP project

Beschreibung: COMPETE 2020 ICT project

Beschreibung: Fundação para a Ciência e a Tecnologia http://dx.doi.org/10.13039/501100001871

Beschreibung: TOMAQAPA

Beschreibung: http://mesonh.aero.obs-mip.fr/mesonh54/Download

Beschreibung: With increasing resolution of numerical weather prediction (NWP) models, classical subgrid‐scale processes become increasingly resolved on the model grid. In particular, turbulence in the planetary boundary layer (PBL) is vertically already partially resolved in contemporary models. For classical local PBL schemes, resulting up‐gradient heat transports cannot be treated correctly. Thus, nonlocal turbulence schemes have been developed in the past. As the horizontal grid sizes of NWP models become smaller than a few kilometers, the large turbulence eddies in the PBL will also start to become partially resolved in the horizontal direction. A very flexible way to formulate nonlocal turbulent exchange is the transilient matrix method, which is used here to develop a new turbulence parameterization. The resulting NLT3D scheme applies transilient mixing matrices to subgrid‐scale transports in all three dimensions. We compare results of WRF real‐case simulations including our scheme, a classical local turbulence scheme (MYNN), and an existing nonlocal one‐dimensional scheme (ACM2) with observations from field campaigns over homogeneous terrain (CASES‐99) and complex terrain (CAPTEX). Over homogeneous terrain, all three schemes similarly well capture the observed surface fluxes and radiosonde profiles, whereas over complex terrain more differences become obvious. During a tracer release experiment (CAPTEX) over the Appalachian mountain region, the mixing and vertical extent of the PBL turn out to be decisive to reproduce the observed advection speed of the tracer‐marked air mass. Deeper mixing not only accelerates surface winds but also enables tracer to travel faster at higher altitudes and then mix back to the ground. As results from a version of NLT3D with only standard horizontal Smagorinsky diffusion (NLT1D) demonstrate, simulating three‐dimensional turbulence can be beneficial already at horizontal grid sizes of a few kilometers.

Beschreibung: Decreasing grid sizes in numerical weather prediction models demand the inclusion of nonlocal effects and horizontal turbulence in turbulence parameterizations. This is the motivation for the development of the nonlocal three‐dimensional turbulence (NLT3D) scheme. Vertical nonlocal mixing accelerates the horizontal transport of near‐surface tracers by fast advection at higher altitudes (see figure), and horizontal turbulence enhances tracer dispersion. As validated by observations, both effects are beneficial to the forecast quality already at grid sizes of a few kilometers.

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: Compound weather and climate events are combinations of climate drivers and/or hazards that contribute to societal or environmental risk. Studying compound events often requires a multidisciplinary approach combining domain knowledge of the underlying processes with, for example, statistical methods and climate model outputs. Recently, to aid the development of research on compound events, four compound event types were introduced, namely (a) preconditioned, (b) multivariate, (c) temporally compounding, and (d) spatially compounding events. However, guidelines on how to study these types of events are still lacking. Here, we consider four case studies, each associated with a specific event type and a research question, to illustrate how the key elements of compound events (e.g., analytical tools and relevant physical effects) can be identified. These case studies show that (a) impacts on crops from hot and dry summers can be exacerbated by preconditioning effects of dry and bright springs. (b) Assessing compound coastal flooding in Perth (Australia) requires considering the dynamics of a non‐stationary multivariate process. For instance, future mean sea‐level rise will lead to the emergence of concurrent coastal and fluvial extremes, enhancing compound flooding risk. (c) In Portugal, deep‐landslides are often caused by temporal clusters of moderate precipitation events. Finally, (d) crop yield failures in France and Germany are strongly correlated, threatening European food security through spatially compounding effects. These analyses allow for identifying general recommendations for studying compound events. Overall, our insights can serve as a blueprint for compound event analysis across disciplines and sectors.

Beschreibung: Plain Language Summary: Many societal and environmental impacts from events such as droughts and storms arise from a combination of weather and climate factors referred to as a compound event. Considering the complex nature of these high‐impact events is crucial for an accurate assessment of climate‐related risk, for example to develop adaptation and emergency preparedness strategies. However, compound event research has emerged only recently, therefore our ability to analyze these events is still limited. In practice, studying compound events is a challenging task, which often requires interaction between experts across multiple disciplines. Recently, compound events were divided into four types to aid the framing of research on this topic, but guidelines on how to study these four types are missing. Here, we take a pragmatic approach and—focusing on case studies of different compound event types—illustrate how to address specific research questions that could be of interest to users. The results allow identifying recommendations for compound event analyses. Furthermore, through the case studies, we highlight the relevance that compounding effects have for the occurrence of landslides, flooding, vegetation impacts, and crop failures. The guidelines emerged from this work will assist the development of compound event analysis across disciplines and sectors.

Beschreibung: Key Points: Using case studies representative of four main compound event types we show how compound event‐related research questions can be tackled. We present user‐friendly guidelines for compound event analysis applicable to different compound event types. We demonstrate that compound events cause vegetation impacts, coastal flooding, landslides, and continental‐scale crop yield failures.

Beschreibung: European COST action DAMOCLES

Beschreibung: NERC

Beschreibung: Swiss National Science Foundation

Beschreibung: Helmholtz Initiative and Networking Fund

Beschreibung: Netherlands Organisation for Scientific Research (NWO)

Beschreibung: Fundação para a Ciência e a Tecnologia

Beschreibung: Scientific Employment Stimulus 2017

Beschreibung: Italian Ministry of University and Research

Beschreibung: European Union's Horizon 2020 research and innovation programme

Beschreibung: AXA Research Fund for support

Beschreibung: Portuguese Foundation for Science and Technology

Beschreibung: Twenty‐first‐century climate change projections are uncertain, especially on regional scales. An important source of uncertainty is that climate models exhibit biases, which limits their ability to predict climate. One of the largest biases is the too warm sea surface temperature (SST) in the eastern tropical Atlantic (TA), reflecting deficient atmospheric and oceanic circulation. Here, we show that CO2‐forced TA‐sector climate changes simulated by state‐of‐the‐art climate models exhibit a strong mean‐state dependence. In particular, models simulating largest SST warming in the eastern TA, consistent with the warming observed since the mid‐20th century, typically exhibit a more realistic mean state than models simulating largest warming in the western TA. The former models exhibit a larger climate sensitivity, and predict stronger and in part qualitatively different climate changes over the TA sector, for example in precipitation. These findings may help to reducing uncertainty in TA‐climate change projections.

Beschreibung: Plain Language Summary: Twenty‐first‐century climate change projections are uncertain, especially on regional scales. An important source of uncertainty is that climate models exhibit biases, which limits their ability to predict climate. One of the largest biases is the too warm sea surface temperature in the eastern tropical Atlantic (TA), reflecting deficient atmospheric and oceanic circulation. Here, we show that CO2‐forced TA‐sector climate changes simulated by state‐of‐the‐art climate models exhibit a strong relationship to the quality of simulating the mean state. These findings may help to reducing uncertainty in climate change projections over the TA sector.

Beschreibung: Key Points: Climate projections for the tropical Atlantic sector depend on the quality of simulating present‐day conditions. Less biased climate models provide more reliable projections. Spread in CO2‐forced climate changes over the Tropical Atlantic region.

Beschreibung: Helmholtz Society

Beschreibung: JPI Climate and JPI Ocean

Beschreibung: German Ministry of Education and Research

Beschreibung: https://www.dkrz.de/up/services/data-management/cmip-data-pool

Beschreibung: https://www.metoffice.gov.uk/hadobs/hadisst/

Beschreibung: https://psl.noaa.gov/data/gridded/data.noaa.ersst.v5.html

Beschreibung: https://psl.noaa.gov/data/gridded/data.cobe2.html

Beschreibung: https://rda.ucar.edu/datasets/ds090.2/

Beschreibung: https://psl.noaa.gov/data/gridded/data.hadslp2.html

Beschreibung: http://www.esrl.noaa.gov/psd/data/gridded/data.coads.2deg.html

Beschreibung: Quantifying the anthropogenic fluxes of CO2 is important to understand the evolution of carbon sink capacities, on which the required strength of our mitigation efforts directly depends. For the historical period, the global carbon budget (GCB) can be compiled from observations and model simulations as is done annually in the Global Carbon Project's (GCP) carbon budgets. However, the historical budget only considers a single realization of the Earth system and cannot account for internal climate variability. Understanding the distribution of internal climate variability is critical for predicting the future carbon budget terms and uncertainties. We present here a decomposition of the GCB for the historical period and the RCP4.5 scenario using single‐model large ensemble simulations from the Max Planck Institute Grand Ensemble (MPI‐GE) to capture internal variability. We calculate uncertainty ranges for the natural sinks and anthropogenic emissions that arise from internal climate variability, and by using this distribution, we investigate the likelihood of historical fluxes with respect to plausible climate states. Our results show these likelihoods have substantial fluctuations due to internal variability, which are partially related to El Niño‐Southern Oscillation (ENSO). We find that the largest internal variability in the MPI‐GE stems from the natural land sink and its increasing carbon stocks over time. The allowable fossil fuel emissions consistent with 3 C warming may be between 9 and 18 Pg C yr−1. The MPI‐GE is generally consistent with GCP's global budgets with the notable exception of land‐use change emissions in recent decades, highlighting that human action is inconsistent with climate mitigation goals.

Beschreibung: Key Points: We use a single‐model large ensemble to estimate uncertainties from internal climate variability in the global carbon budget. The land sink accounts for most internal climate uncertainty which may permit 9–18 Pg C yr−1 in allowable emissions by 2050 (for 3°C warming).

Beschreibung: European Union's Horizon 2020

Beschreibung: research

Beschreibung: Water isotopologues, as natural tracers of the hydrological cycle on Earth, provide a unique way to assess the skill of climate models in representing realistic atmospheric‐terrestrial water pathways. This study presents the newly developed WRF‐Hydro‐iso, which is a version of the coupled atmospheric‐hydrological WRF‐Hydro model enhanced with a joint soil‐vegetation‐atmospheric description of water isotopologue motions. It allows the consideration of isotopic fractionation processes during water phase changes in the atmosphere, the land surface, and the subsurface. For validation, WRF‐Hydro‐iso is applied to two different climate zones, namely Europe and Southern Africa under the present climate conditions. Each case is modeled with a domain employing a 5 km grid‐spacing coupled with a terrestrial subgrid employing a 500 m grid‐spacing in order to represent lateral terrestrial water flow. A 10‐year slice is simulated for 2003–2012, using ERA5 reanalyses as driving data. The boundary condition of isotopic variables is prescribed with mean values from a 10‐year simulation with the Community Earth System Model Version 1. WRF‐Hydro‐iso realistically reproduces the climatological variations of the isotopic concentrations δPO18 and δPH2 from the Global Network of Isotopes in Precipitation. In a sensitivity analysis, it is found that land surface evaporation fractionation increases the isotopic concentrations in the rootzone soil moisture and slightly decreases the isotopic concentrations in precipitation. Lateral terrestrial water flow minorly affects these isotopic concentrations through changes in evaporation‐transpiration partitioning.

Beschreibung: Plain Language Summary: Global climate models are limited by their coarse resolution, which may reduce their meaningfulness. This problem can be circumvented for a specific region with regional climate models, which provide, for example, a detailed description of clouds and land‐atmosphere interactions. But it remains a question: How realistic is the model representation of water transport through the different compartments of the hydrological cycle, the atmosphere, the land, and the sea? A unique way to assess modeled water transport is the comparison to natural tracers, such as water isotopologues, which requires to include the fate of these water isotopologues in the model. This is what we pursue here with the newly developed WRF‐Hydro‐iso model. A model description and a proof of concept are provided for two climate zones, using the Global Network of Isotopes in Precipitation data set as reference.

Beschreibung: Key Points: A new coupled atmospheric‐hydrological regional modeling system of water isotopologues is presented. Land surface evaporation fractionation increases the isotopic concentrations in the rootzone. Lateral terrestrial water flow has a minor effect on isotopic concentrations in the rootzone.

Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659

Beschreibung: German Federal Ministry of Science and Education

Beschreibung: Bavarian State Ministry of Science and the Arts

Beschreibung: Weather regime forecasts are a prominent use case of sub‐seasonal prediction in the midlatitudes. A systematic evaluation and understanding of year‐round sub‐seasonal regime forecast performance is still missing, however. Here we evaluate the representation of and forecast skill for seven year‐round Atlantic–European weather regimes in sub‐seasonal reforecasts from the European Centre for Medium‐Range Weather Forecasts. Forecast calibration improves regime frequency biases and forecast skill most strongly in summer, but scarcely in winter, due to considerable large‐scale flow biases in summer. The average regime skill horizon in winter is about 5 days longer than in summer and spring, and 3 days longer than in autumn. The Zonal Regime and Greenland Blocking tend to have the longest year‐round skill horizon, which is driven by their high persistence in winter. The year‐round skill is lowest for the European Blocking, which is common for all seasons but most pronounced in winter and spring. For the related, more northern Scandinavian Blocking, the skill is similarly low in winter and spring but higher in summer and autumn. We further show that the winter average regime skill horizon tends to be enhanced following a strong stratospheric polar vortex (SPV), but reduced following a weak SPV. Likewise, the year‐round average regime skill horizon tends to be enhanced following phases 4 and 7 of the Madden–Julian Oscillation (MJO) but reduced following phase 2, driven by winter but also autumn and spring. Our study thus reveals promising potential for year‐round sub‐seasonal regime predictions. Further model improvements can be achieved by reduction of the considerable large‐scale flow biases in summer, better understanding and modeling of blocking in the European region, and better exploitation of the potential predictability provided by weak SPV states and specific MJO phases in winter and the transition seasons.

Beschreibung: The overall sub‐seasonal forecast performance (biases and skill) for predicting seven year‐round Atlantic–European weather regimes is highest in winter and lowest in summer. The year‐round skill horizon is shortest for the European Blocking and longest for the Zonal Regime and Greenland Blocking (see figure). Furthermore, the winter skill horizon tends to be enhanced following a strong stratospheric polar vortex but reduced following a weak one. Madden–Julian Oscillation phases 4 and 7 tend to increase and phase 2 to decrease the year‐round skill horizon.

Beschreibung: Helmholtz‐Gemeinschaft http://dx.doi.org/10.13039/501100001656

Beschreibung: We investigate the glacial climate conditions in the southeastern Carpathian Basin (Vojvodina, Serbia) based on the reconstruction of malacological palaeotemperatures and results from a high‐resolution regional climate simulation. Land snail assemblages from eight loess profiles are used to reconstruct July temperatures during the Last Glacial Maximum (LGM). The malacological reconstructed temperatures are in good agreement with the simulated LGM July temperatures by the Weather Research and Forecast model. Both methods indicate increasing temperatures from the northwestern towards the southeastern parts of the study area. LGM aridity indices calculated based on the regional climate model data suggest more arid conditions in the southeastern parts compared with more humid conditions in the northwestern parts. However, for present‐day conditions, the moisture gradient is reversed, exhibiting more humid (arid) conditions in the southeast (northwest). An explanation for the reversed LGM aridity pattern is provided by an analysis of the prevailing wind directions over the South Banat district (Serbia). The prevailing moist northwesterly winds during summer are not able to compensate for the annual lack of moisture induced by the dry winds from the southeast that are more frequent during the LGM for the other seasons.

Beschreibung: Helmholtz Association http://dx.doi.org/10.13039/501100009318

Beschreibung: Past Global Changes http://dx.doi.org/10.13039/100010439

Beschreibung: The Tianshan Mountains, with their status as ‘water tower’, receive quantities of precipitation that are among the highest in Central Asia. There are considerable knowledge gaps regarding the understanding of spatial and temporal patterns of precipitation over this water‐scarce region. Based on the Global Precipitation Climatology Centre (GPCC) data set, this study evaluated the precipitation variations over Tianshan Mountains on different time scales by using Mann‐Kendall (M‐K) test approaches and the ensemble empirical mode decomposition (EEMD) method. The results show that (a) most parts of Tianshan experienced increasing annual precipitation during 1950–2016 while Western Tianshan, which is the wettest region, faced a downtrend of precipitation during the same 67 years; (b) the annual precipitation in the Tianshan Mountains has exhibited high‐frequency variations with 3‐ and 6‐year quasi‐periods and low‐frequency variations with 12‐, 27‐year quasi‐periods. On the decadal scale, Tianshan had two dry periods (1950–1962 and 1973–1984) and two wet periods (1962–1972 and 1985–2016) and has experienced a tendency of continuous humidification since 2004; (c) the precipitation over the Tianshan Mountains shows a strong seasonality. In total, 63.6% of all precipitation falls in spring and summer. Distinctive differences are found in seasonal precipitation variations among the sub‐Tianshan regions. Obvious upward trends of precipitation over Eastern Tianshan were found in all seasons, with Eastern Tianshan entering a humid period as early as 1986. Northern and Central Tianshan experienced a decreasing trend in summer and spring. However, in the other seasons, those two sub‐Tianshan regions have been in humid periods since the 1990s. The precipitation over Western Tianshan showed an upward trend in summer and autumn. The obvious downward trends in spring and winter have led to dry periods in these two seasons from 1997–2014 to 2008–2016, respectively.

Beschreibung: Most parts of Tianshan experienced increasing annual precipitation during 1950–2016 while Western Tianshan, which is the wettest region, faced a downtrend of precipitation during the same 67 years. Distinctive differences are found in seasonal precipitation variations among the sub‐Tianshan regions.

Beschreibung: Humboldt‐Universität zu Berlin National Natural Science Foundation of China

Beschreibung: China Scholarship Council (CSC)

Beschreibung: The European Space Agency Earth Explorer mission Aeolus with the first spaceborne Doppler Wind Lidar onboard provides global coverage of wind profiles twice per day. This paper discusses the impact of assimilating Aeolus winds on the quality of tropical analyses and forecasts using the observing system experiments of the European Centre for Medium‐Range Weather (ECMWF). Presented examples show that Aeolus wind profiles bring changes to the Kelvin wave structure in the layers with a significant vertical shear during the easterly phase of the quasi‐biennial oscillation in the period May to September 2020. Comparing Kelvin waves in analyses and forecasts with and without Aeolus winds, it is argued that improved ECMWF forecasts in the tropical tropopause layer are due to vertically propagating Kelvin waves.

Beschreibung: Plain Language Summary: The tropics are the region with the largest uncertainties in the initial states for numerical weather prediction, called analyses. Analysis uncertainties are largest in the tropical upper troposphere and the lower stratosphere (UTLS). One of the reasons is a lack of wind profiles which are more useful than temperature profiles in the tropics. This classical effect was described by Smagorinsky as “Not all data are equal in their information‐yielding capacity. Some are more equal than others.” ESA's ongoing Aeolus mission provides the first global wind profile observations from space. Despite their small number and relatively large random error, Aeolus winds have a positive impact on the quality of global weather forecasts, especially in the UTLS. In this paper, we discuss the impact of the Aeolus winds in UTLS focusing on the vertically propagating Kelvin waves, which are a major contributor to tropical variability. Several case studies are presented using the ECMWF model and data assimilation with and without Aeolus winds. The studied period May to September 2020 was characterized by a weakening easterly phase of the quasi‐biennial oscillation (QBO). Results suggest that a stronger impact of Aeolus winds in May than later in summer was associated with the QBO and the background flow.

Beschreibung: Key Points: Impact of assimilating Aeolus winds in the ECMWF system from May to September 2020 is coupled to the easterly QBO phase. Aeolus assimilation modifies the representation of vertically propagating Kelvin waves in the tropical UTLS. Forecast improvements in May 2020 could be associated with the alteration in the upward‐propagating Kelvin waves.

Beschreibung: European Space Agency (ESA) http://dx.doi.org/10.13039/501100000844

Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659

Beschreibung: https://doi.org/10.5281/zenodo.5207392

Beschreibung: Molecular hydrogen (H2) released during serpentinization of mantle rocks is one of the main fuels for chemosynthetic life. Processes of H2 production at slow-spreading mid-ocean ridges (MORs) have received much attention in the past. Less well understood is serpentinization at passive continental margins where different rock types are involved (lherzolite instead of harzburgite/dunite at MORs) and the alteration temperatures tend to be lower (〈200°C vs. 〉200°C). To help closing this knowledge gap we investigated drill core samples from the West Iberia margin. Lherzolitic compositions and spinel geochemistry indicate that the exhumed peridotites resemble sub-continental lithospheric mantle. The rocks are strongly serpentinized, mainly consist of serpentine with little magnetite, and are generally brucite-free. Serpentine can be uncommonly Fe- rich, with XMg Mg/(Mg + Fe) 〈 0.8, and shows distinct compositional trends toward a cronstedtite endmember. Bulk rock and silicate fraction Fe(III)/ Fe ratios are 0.6–0.92 and 0.58–0.8, respectively; our data show that 2/3 of the ferric Fe is accounted for by Fe(III)- serpentine. Mass balance and thermodynamic calculations suggest that the sample’s initial serpentinization produced ∼120 to 〉300 mmol H2 per kg rock. The cold, late-stage weathering of the serpentinites at the seafloor caused additional H2 formation. These results suggest that the H2 generation potential evolves during the transition from continental break-up to ultraslow and, eventually, slow MOR spreading. Metamorphic phase assemblages systematically vary between these settings, which has consequences for H2 yields during serpentinization. At magma-poor rifted margins and ultraslow- spreading MORs, serpentine hosts most Fe(III). Hydrogen yields of 120 to 〉300 mmol and 50–150 mmol H2 per kg rock, respectively, may be expected at temperatures of 〈200°C. At slow-spreading MORs, in contrast, serpentinization may produce 200–350 mmol H2, most of which is related to magnetite formation at 〉200°C. Since, in comparison to slow-spreading MORs, geothermal gradients at magma-poor margins and ultraslow-spreading MORs are lower, larger volumes of low-temperature serpentinite should form in these settings. Serpentinization of lherzolitic rocks at magma-poor margins should produce particularly high amounts of H2 under conditions within the habitable zone. Magma-poor margins may hence be more relevant environments for hydrogenotrophic microbial life than previously thought.

Beschreibung: research

Beschreibung: https://doi.org/10 .1594/PANGAEA.920208

Beschreibung: research

Beschreibung: Few data exist that provide insight into pro- cesses affecting the long-term carbon cycle at shallow fore- arc depths. To better understand the mobilization of C in sediments and crust of the subducting slab, we investigated carbonate materials that originate from the subduction chan- nel at the Mariana forearc (〈 20 km) and were recovered during International Ocean Discovery Program Expedition 366. Calcium carbonates occur as vein precipitates within metavolcanic and metasedimentary clasts. The clasts repre- sent portions of the subducting lithosphere, including ocean island basalt, that were altered at lower blueschist facies conditions and were subsequently transported to the fore- arc seafloor by serpentinite mud volcanism. Euhedral arag- onite and calcite and the lack of deformation within the veins suggest carbonate formation in a stress-free environ- ment after peak metamorphism affected their hosts. Inter- growth with barite and marked negative Ce anomalies in car- bonate attest the precipitation within a generally oxic envi- ronment, that is an environment not controlled by serpen- tinization. Strontium and O isotopic compositions in car- bonate (87Sr/86Sr = 0.7052 to 0.7054, δ18OVSMOW = 20 to 24 ‰) imply precipitation from slab-derived fluids at tem- peratures between ∼ 130 and 300 ◦C. These temperature es- timates are consistent with the presence of blueschist facies phases such as lawsonite coexisting with the carbonates in some veins. Incorporated C is inorganic (δ13CVPDB = −1 ‰ to +4 ‰) and likely derived from the decarbonation of cal- careous sediment and/or oceanic crust. These findings pro- vide evidence for the mobilization of C in the downgoing slab at depths of 〈 20 km. Our study shows for the first time in detail that a portion of this C forms carbonate precipitates in the subduction channel of an active convergent margin. This process may be an important asset in understanding the deep carbon cycle since it highlights that some C is lost from the subducting lithosphere before reaching greater depths.

Beschreibung: research

Beschreibung: Changes in penguin populations on the Antarctic Peninsula have been linked to several environmental factors, but the potentially devastating impact of volcanic activity has not been considered. Here we use detailed biogeochemical analyses to track past penguin colony change over the last 8,500 years on Ardley Island, home to one of the Antarctic Peninsula’s largest breeding populations of gentoo penguins. The first sustained penguin colony was established on Ardley Island c. 6,700 years ago, pre-dating sub-fossil evidence of Peninsula- wide occupation by c. 1,000 years. The colony experienced five population maxima during the Holocene. Overall, we find no consistent relationships with local-regional atmospheric and ocean temperatures or sea-ice conditions, although the colony population maximum, c. 4,000–3,000 years ago, corresponds with regionally elevated temperatures. Instead, at least three of the five phases of penguin colony expansion were abruptly ended by large eruptions from the Deception Island volcano, resulting in near-complete local extinction of the colony, with, on average, 400–800 years required for sustainable recovery.

Beschreibung: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3080_ESM.xlsx

Beschreibung: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3081_ESM.xlsx

Beschreibung: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3082_ESM.xlsx

Beschreibung: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3083_ESM.xlsx

Beschreibung: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3084_ESM.xlsx

Beschreibung: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3085_ESM.xlsx

Beschreibung: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3086_ESM.xlsx

Beschreibung: research

Beschreibung: Existing climate projections and impact assessments in Nepal only consider a limited number of generic climate indices such as means. Few studies have explored climate extremes and their sectoral implications. This study evaluates future scenarios of extreme climate indices from the list of the Expert Team on Sector-specific Climate Indices (ET-SCI) and their sectoral implications in the Karnali Basin in western Nepal. First, future projections of 26 climate indices relevant to six climate-sensitive sectors in Karnali are made for the near (2021–2045), mid (2046–2070), and far (2071–2095) future for low- and high-emission scenarios (RCP4.5 and RCP8.5, respectively) using bias-corrected ensembles of 19 regional climate models from the COordinated Regional Downscaling EXperiment for South Asia (CORDEX-SA). Second, a qualitative analysis based on expert interviews and a literature review on the impact of the projected climate extremes on the climate-sensitive sectors is undertaken. Both the temperature and precipitation patterns are projected to deviate significantly from the historical reference already from the near future with increased occurrences of extreme events. Winter in the highlands is expected to become warmer and dryer. The hot and wet tropical summer in the lowlands will become hotter with longer warm spells and fewer cold days. Low-intensity precipitation events will decline, but the magnitude and frequency of extreme precipitation events will increase. The compounding effects of the increase in extreme temperature and precipitation events will have largely negative implications for the six climate-sensitive sectors considered here.

Beschreibung: Rheinische Friedrich-Wilhelms-Universität Bonn (1040)

Beschreibung: Integrating palaeoclimatological proxies and historical records, which is necessary to achieve a more complete understanding of climate impacts on past societies, is a challenging task, often leading to unsatisfactory and even contradictory conclusions. This has until recently been the case for Italy, the heart of the Roman Empire, during the transition between Antiquity and the Middle Ages. In this paper, we present new high-resolution speleothem data from the Apuan Alps (Central Italy). The data document a period of very wet conditions in the sixth c. AD, probably related to synoptic atmospheric conditions similar to a negative phase of the North Atlantic Oscillation. For this century, there also exist a significant number of historical records of extreme hydroclimatic events, previously discarded as anecdotal. We show that this varied evidence reflects the increased frequency of floods and extreme rainfall events in Central and Northern Italy at the time. Moreover, we also show that these unusual hydroclimatic conditions overlapped with the increased presence of “water miracles” in Italian hagiographical accounts and social imagination. The miracles, performed by local Church leaders, strengthened the already growing authority of holy bishops and monks in Italian society during the crucial centuries that followed the “Fall of the Roman Empire”. Thus, the combination of natural and historical data allows us to show the degree to which the impact of climate variability on historical societies is determined not by the nature of the climatic phenomena per se, but by the culture and the structure of the society that experienced it.

Beschreibung: Fondazione Cassa di Risparmio di Lucca

Beschreibung: European Research Council http://dx.doi.org/10.13039/501100000781

Beschreibung: Earth’s climatic evolution over the last 5 million years is primarily understood from the perspective of marine mechanisms, however, the role of terrestrial feedbacks remains largely unexplored. Here we reconstruct the last 5 million years of soil moisture variability in Central Asia using paleomagnetism data and isotope geochemistry of an 80 m-thick sedimentary succession at Charyn Canyon, Kazakhstan. We identify a long-term trend of increasing aridification throughout the period, along with shorter-term variability related to the interaction between mid-latitude westerlies and the Siberian high-pressure system. This record highlights the long-term contribution of mid-latitude Eurasian terrestrial systems to the modulation of moisture transfer into the Northern Hemisphere oceans and back onto land via westerly air flow. The response of Earth-surface dynamics to Plio-Pleistocene climatic change in Central Asia likely generated terrestrial feedbacks affecting ocean and atmospheric circulation. This missing terrestrial link elucidates the significance of land-water feedbacks for long-term global climate.

Beschreibung: Late Cenozoic variation in Central Asian hydroclimate resulted from the interaction between mid-latitude westerlies and the Siberian high-pressure system and may have driven terrestrial feedbacks, according to analyses of sediments from Charyn Canyon, Kazakhstan.

Beschreibung: Palaeomagnetic, rock magnetic and grain-size analyses were funded by the grant CNPq

Beschreibung: Deutsche Forschungsgemeinschaft (German Research Foundation) https://doi.org/10.13039/501100001659

Beschreibung: Wilhelm und Else Heraeus-Stiftung (Wilhelm and Else Heraeus Foundation) https://doi.org/10.13039/501100011618

Beschreibung: https://doi.org/10.17632/v9s3bhn27k.1

Beschreibung: In mountain environments dimensions of climate change are unclear because of limited availability of meteorological stations. However, there is a necessity to assess the scope of local climate change, as the livelihood and food systems of subsistence-based communities are already getting impacted. To provide more clarity about local climate trends in the Pamir Mountains of Tajikistan, this study integrates measured climate data with community observations in the villages of Savnob and Roshorv. Taking a transdisciplinary approach, both knowledge systems were considered as equally pertinent and mutually informed the research process. Statistical trends of temperature and snow cover were retrieved using downscaled ERA5 temperature data and the snow cover product MOD10A1. Local knowledge was gathered through community workshops and structured interviews and analysed using a consensus index. Results showed, that local communities perceived increasing temperatures in autumn and winter and decreasing amounts of snow and rain. Instrumental data records indicated an increase in summer temperatures and a shortening of the snow season in Savnob. As both knowledge systems entail their own strengths and limitations, an integrative assessment can broaden the understanding of local climate trends by (i) reducing existing uncertainties, (ii) providing new information, and (iii) introducing unforeseen perspectives. The presented study represents a time-efficient and global applicable approach for assessing local dimensions of climate change in data-deficient regions.

Beschreibung: Projekt DEAL

Beschreibung: Drought is the absence or below-required supply of precipitation, runoff and or moisture for an extended time period. Modelling drought is relevant in assessing drought incidence and pattern. This study aimed to model the spatial variation and incidence of the 2018 drought in Brandenburg using GIS and remote sensing. To achieve this, we employed a Multi-Criteria Approach (MCA) by using three parameters including Precipitation, Land Surface Temperature and Normalized Difference Vegetation Index (NDVI). We acquired the precipitation data from Deutsche Wetterdienst, Land Surface Temperature and NDVI from Landsat 8 imageries on the USGS Earth Explorer. The datasets were analyzed using ArcGIS 10.7. The information from these three datasets was used as parameters in assessing drought prevalence using the MCA. The MCA was used in developing the drought model, ‘PLAN’, which was used to classify the study area into three levels/zones of drought prevalence: moderate, high and extreme drought. We went further to quantify the agricultural areas affected by drought in the study area by integrating the land use map. Results revealed that 92% of the study area was severely and highly affected by drought especially in districts of Oberhavel, Uckermark, Potsdam-Staedte, and Teltow-Flaeming. Finding also revealed that 77.54% of the total agricultural land falls within the high drought zones. We advocated for the application of drought models (such as ‘PLAN’), that incorporates flexibility (tailoring to study needs) and multi-criteria (robustness) in drought assessment. We also suggested that adaptive drought management should be championed using drought prevalence mapping.

Beschreibung: Rheinische Friedrich-Wilhelms-Universität Bonn (1040)

Beschreibung: Atmospheric circulation is a vital process in the transport of heat, moisture, and pollutants around the globe. The variability of rainfall depends to some extent on the atmospheric circulation. This paper investigates synoptic situations in southern Africa that can be associated with wet days and dry days in Free State, South Africa, in addition to the underlying dynamics. Principal component analysis was applied to the T-mode matrix (variable is time series and observation is grid points at which the field was observed) of daily mean sea level pressure field from 1979 to 2018 in classifying the circulation patterns in southern Africa. 18 circulation types (CTs) were classified in the study region. From the linkage of the CTs to the observed rainfall data, from 11 stations in Free State, it was found that dominant austral winter and late austral autumn CTs have a higher probability of being associated with dry days in Free State. Dominant austral summer and late austral spring CTs were found to have a higher probability of being associated with wet days in Free State. Cyclonic/anti-cyclonic activity over the southwest Indian Ocean, explained to a good extent, the inter-seasonal variability of rainfall in Free State. The synoptic state associated with a stronger anti-cyclonic circulation at the western branch of the South Indian Ocean high-pressure, during austral summer, leading to enhanced low-level moisture transport by southeast winds was found to have the highest probability of being associated with above-average rainfall in most regions in Free State. On the other hand, the synoptic state associated with enhanced transport of cold dry air, by the extratropical westerlies, was found to have the highest probability of being associated with (winter) dryness in Free State.

Beschreibung: Julius-Maximilians-Universität Würzburg (3088)

Beschreibung: https://www.ecmwf.int/en/forecasts/datasets/reanalysis-datasets/era-interim

Beschreibung: http://www.dwa.gov.za/Hydrology/Verified/hymain.aspx

Beschreibung: Megadroughts are notable manifestations of the American Southwest, but not so much of the European climate. By using long-term hydrological and meteorological observations, as well as paleoclimate reconstructions, here we show that central Europe has experienced much longer and severe droughts during the Spörer Minimum (~AD 1400–1480) and Dalton Minimum (~AD 1770–1840), than the ones observed during the 21st century. These two megadroughts appear to be linked with a cold state of the North Atlantic Ocean and enhanced winter atmospheric blocking activity over the British Isles and western part of Europe, concurrent with reduced solar forcing and explosive volcanism. Moreover, we show that the recent drought events (e.g., 2003, 2015, and 2018), are within the range of natural variability and they are not unprecedented over the last millennium.

Beschreibung: Central Europe experienced long-lasting droughts during the Spörer and Dalton solar minima around AD 1450 and 1800 that were more severe and extensive than those observed in the 21st century, according to palaeoclimate reconstructions.

Beschreibung: Predicting rainfall-induced landslides hinges on the quality of the rainfall product. Satellite rainfall estimates or rainfall reanalyses aid in studying landslide occurrences especially in ungauged areas, or in the absence of ground-based rainfall radars. Quality of these rainfall estimates is critical; hence, they are commonly crosschecked with their ground-based counterparts. Beyond their temporal precision compared to ground-based observations, we investigate whether these rainfall estimates are adequate for hindcasting landslides, which particularly requires accurate representation of spatial variability of rainfall. We developed a logistic regression model to hindcast rainfall-induced landslides in two sites in Japan. The model contains only a few topographic and geologic predictors to leave room for different rainfall products to improve the model as additional predictors. By changing the input rainfall product, we compared GPM IMERG and ERA5 rainfall estimates with ground radar–based rainfall data. Our findings emphasize that there is a lot of room for improvement of spatiotemporal prediction of landslides, as shown by a strong performance increase of the models with the benchmark radar data attaining 95% diagnostic performance accuracy. Yet, this improvement is not met by global rainfall products which still face challenges in reliably capturing spatiotemporal patterns of precipitation events.

Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347

Beschreibung: Disaster Prevention Research Institute, Kyoto University http://dx.doi.org/10.13039/501100006086

Beschreibung: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655

Beschreibung: Lake‐level reconstructions are a key tool in hydro‐climate reconstructions, based on the assumption that lake‐level changes primarily reflect climatic changes. Although it is known that land cover changes can affect evapotranspiration and groundwater formation, this factor commonly receives little attention in the interpretation of past lake‐level changes. To address this issue in more detail, we explore the effects of land cover change on Holocene lake‐level fluctuations in Lake Tiefer See in the lowlands of northeastern Germany. We reconstruct lake‐level changes based on the analysis of 28 sediment records from different water depths and from the shore. We compare the results with land cover changes inferred from pollen data. We also apply hydrological modelling to quantify effects of land cover change on evapotranspiration and the lake level. Our reconstruction shows an overall lake‐level amplitude of about 10 m during the Holocene, with the highest fluctuations during the Early and Late Holocene. Only smaller fluctuations during the Middle Holocene can unambiguously be attributed to climatic fluctuations because the land cover was stable during that period. Fluctuations during the Early and Late Holocene are at least partly related to changes in natural and anthropogenic land cover. For several intervals the reconstructed lake‐level changes agree well with variations in modelled groundwater recharge inferred from land cover changes. In general, the observed amplitudes of lake‐level fluctuations are larger than expected from climatic changes alone and thus underline that land cover changes in lake catchments must be considered in climatic interpretations of past lake‐level fluctuations.

Beschreibung: Helmholtz Association http://dx.doi.org/10.13039/501100001656

Beschreibung: Leibniz‐Gemeinschaft http://dx.doi.org/10.13039/501100001664

Beschreibung: While the evidence for anthropogenic climate change continues to strengthen, and concerns about severe weather events are increasing, global projections of regional climate change are still uncertain due to model‐dependent changes in large‐scale atmospheric circulation, including over North Atlantic and Europe. Here, the Jenkinson–Collison classification of daily circulation patterns is used to evaluate past and future changes in their seasonal frequencies over Central Europe for the 1900–2100 period. Three reanalyses and eight global climate models from the Coupled Model Intercomparison Project phase 6, were used based on daily mean sea‐level pressure data. Best agreement in deriving relative frequencies of the synoptic types was found between the reanalyses. Global models can generally capture the interannual variability of circulation patterns and their climatological state, especially for the less frequent synoptic types. Based on historical data and the shared socioeconomic pathway 5 scenario, the evaluated trends show more robust signals during summer, given their lesser internal variability. Increasing frequencies were found for circulation types characterized by weak pressure gradients, mainly at the expense of decreasing frequencies of westerlies. Our findings indicate that given a high‐emission scenario, these signals will likely emerge from past climate variability towards the mid‐21st century for most altered circulation patterns.

Beschreibung: Daily synoptic circulation patterns are derived using the Jenkinson–Collinson automated classification over Central Europe to evaluate past and future changes in their temporal frequencies. Reanalyses and eight global climate models from the CMIP6 were used based on the historical experiment and a high‐emission scenario. More robust signals were found during the summer season leading to emerging changes towards the mid‐21st century.

Beschreibung: H2020 Marie Skłodowska‐Curie Actions http://dx.doi.org/10.13039/100010665

Beschreibung: EU International Training Network (ITN) Climate Advanced Forecasting of sub‐seasonal Extremes (CAFE)

Beschreibung: Smallholder livelihoods throughout Central America are built on rain‐fed agriculture and depend on seasonal variations in temperature and precipitation. Recent climatic shifts in this highly diverse region are not well understood due to sparse observations, and as the skill of global climate products have not been thoroughly evaluated. We examine the performance for several reanalysis and satellite‐based global climate data products (CHIRPS/CHIRTS, ERA5, MERRA‐2, PERSIANN‐CDR) as compared to the observation‐based GPCC precipitation dataset. These datasets are then used to evaluate the magnitude and spatial extent of hydroclimatic shifts and changes in aridity and drought over the last four decades. We focus on water‐limited regions that are important for rain‐fed agriculture and particularly vulnerable to further drying, and newly delineate those regions for Central America and Mexico by adapting prior definitions of the Central American Dry Corridor. Our results indicate that the CHIRPS dataset exhibits the greatest skill for the study area. A general warming of 0.2–0.8°C·decade−1 was found across the region, particularly for spring and winter, while widespread drying was indicated by several measures for the summer growing season. Changes in annual precipitation have been inconsistent, but show declines of 20–25% in eastern Honduras/Nicaragua and in several parts of Mexico. Some regions most vulnerable to drying have been subject to statistically significant trends towards summer drying, increases in drought and aridity driven by precipitation declines, and/or a lengthening of the winter dry season, highlighting areas where climate adaptation measures may be most urgent.

Beschreibung: Over the past four decades, precipitation trends are the main driver of drought trends, with temperature trends playing a small role. The most widespread drying and increases in aridity have occurred during the summer growing season. Based on delimitations of water‐limited and climate‐sensitive regions (brown shading) that are important for rain‐fed agriculture, some of these highly vulnerable regions overlap with areas of significant drying (red), highlighting potential prioritization areas for climate adaptation measures. image

Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659

Beschreibung: Frias Institute of Advanced Studies (FRIAS) http://dx.doi.org/10.13039/501100003190

Beschreibung: National Science Foundation http://dx.doi.org/10.13039/100000001

Beschreibung: Fully accounting for the climate impact of aviation requires a process-level understanding of the impact of aircraft soot particle emissions on the formation of ice clouds. Assessing this impact with the help of global climate models remains elusive and direct observations are lacking. Here we use a high-resolution cirrus column model to investigate how aircraft-emitted soot particles, released after ice crystals sublimate at the end of the lifetime of contrails and contrail cirrus, perturb the formation of cirrus. By allying cloud simulations with a measurement-based description of soot-induced ice formation, we find that only a small fraction (〈1%) of the soot particles succeeds in forming cloud ice alongside homogeneous freezing of liquid aerosol droplets. Thus, soot-perturbed and homogeneously-formed cirrus fundamentally do not differ in optical depth. Our results imply that climate model estimates of global radiative forcing from interactions between aircraft soot and large-scale cirrus may be overestimates. The improved scientific understanding reported here provides a process-based underpinning for improved climate model parametrizations and targeted field observations.

Beschreibung: Only a small part of aircraft-soot–cirrus interactions succeeds in forming cloud ice, according to simulations with a numerical cirrus cloud model. This suggests that radiative forcing from aircraft soot may have been overestimated.

Beschreibung: https://doi.org/10.5281/zenodo.4709994

Beschreibung: https://doi.org/10.1029/2019JD031847

Beschreibung: On the Qinghai-Tibetan Plateau, the ecological crisis appears in every physical and social aspect, and typically affects the rangelands on which most local people depend for their livelihood. Until today, however, changes in land use and vegetation cover on this Plateau have not yet been adequately and practically treated in studying the framework of sustainability. This thesis deals first with the basic ecological influences and interactions before reviewing their implications for development. The limitations of an ecological perspective is recognized, but this stems mainly from the misapplication of perspective and should not detract from its value. Ecology is undoubtedly the most basic and pervasive of the many determinants of the pastoral production systems of the high-frigid land. To ignore ecology or to fail to take it into account is to court disaster. The amount of literature reflects the importance of the subject but is not reviewed here in any detail; rather the aim is simply to set the scene for later discussions.

Beschreibung: thesis

Beschreibung: DFG, SUB Göttingen

Beschreibung: Der vorliegende Band 52 der Abhandlungen „Anthropogeographie“ des Instituts für Geographische Wissenschaften der Freien Universität Berlin erfasst mit 54 Beiträgen den wissenschaftlichen Forschungsstand der IGU-Kommission “Urban Development and Urban Life”. Die vorgelegten Fassungen stellen die diskutierte und revidierte Form der Beiträge dar, die während der Jahrestagung der Kommission vom 15. bis 20. August 1994 in Berlin gehalten wurden. Die Tagung selbst stand unter dem Thema “Urban Transition and Quality of Life” und forderte damit in den jeweils zwei Einführungs- und zahlreichen weiterführenden Referaten der drei Arbeitsthemen 1) “Restructuring Urban Systems in Central and Eastern Europe“, 2) “Unemployment and Informal Economy in Cities” und 3) “Urban Identity, City Image and Urban Marketing” zu Bewertungen des Forschungsstandes bzw. kritischen Stellungnahmen durch aktuelle Forschungen heraus.

Beschreibung: 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0004.pdf"〉Titelseite〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0005.pdf"〉Titelseite〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0006.pdf"〉Vorwort〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0007.pdf"〉Foreword〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0008.pdf"〉Inhaltsverzeichnis〈/a〉〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0009.pdf"〉I. Introduction〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0010.pdf"〉Reflections Between Urban and University Structures and Planning〈/a〉〈br〉(Dietz, K., Braun, G. O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0011.pdf"〉Berlin - Metropolis in Transition: The State of Urban Development in 1994〈/a〉〈br〉(Ellger, C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0014.pdf"〉Planning for the Future of Berlin〈/a〉〈br〉(Branoner, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0016.pdf"〉Strategic Planning in Berlin〈/a〉〈br〉(Braun, G. O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0019.pdf"〉Change in the Urban Structure in the Five New Länder: The Example of Eisenach〈/a〉〈br〉(Cassel, M., Schwaderer, G.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0021.pdf"〉II. Restructuring of Inter- and Intra-Urban Systems〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0022.pdf"〉Questions on Hierarchical Change in Urban Systems in Eastern and Central Europe〈/a〉〈br〉(Rey, V.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0026.pdf"〉Urban and Urban System Development in Central and Eastern Europe〈/a〉〈br〉(Grimm, F.-D., Taege, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0030.pdf"〉The Impact of Recent Socio-Political and Economic Changes on the Development of Slovenian Towns〈/a〉〈br〉(Pak, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0033.pdf"〉An Urban Evolution Model Applied to Romania's Towns〈/a〉〈br〉(Ianos, I.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0038.pdf"〉Warsaw: Development Problems and Strategies〈/a〉〈br〉(Korcelli, P., Potrykowska, A., Weclawowicz, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0039.pdf"〉The Urban System and Emerging Structure: An Application of Gibb's Measure to the Case of India〈/a〉〈br〉(Mookherjee, D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0041.pdf"〉Reorganisation of the Urban System in Sri Lanka〈/a〉〈br〉(Wanasinghe, D. S.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0046.pdf"〉The Formation of an European Urban System〈/a〉〈br〉(Rozenblat, C., Pumain, D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0051.pdf"〉On the Impact of Internationalization Process on the Finnish Settlement System〈/a〉〈br〉(Palomäki, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0055.pdf"〉Global Perspective of Seoul as a World City in the Region of Pacific Rims〈/a〉〈br〉(Kim, I.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0057.pdf"〉Urban Systems Dynamics: Evidence for the Toronto Urban System: 1930-1991〈/a〉〈br〉(Preston, R. E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0060.pdf"〉The Growth of Toronto: A Market-Share Approach〈/a〉〈br〉(Simmons, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0064.pdf"〉Industrial Restructuring and Urban Development: An Examination in Metropolitan Detroit〈/a〉〈br〉(Sinclair, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0067.pdf"〉Counter-Urbanization in Perspective: Images and Reality in Settlement System Change〈/a〉〈br〉(Davies, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0069.pdf"〉Urban Region as a Geoeconomic and Geopolitical Unit in "A Europe of Regions"〈/a〉〈br〉(Vartiainen, P.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0070.pdf"〉The Ethnic and Social Division of a World City: The Case of London〈/a〉〈br〉(Petsimeris, P.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0075.pdf"〉Transformation in the South African Apartheid City – Residential Desegregation in Pietersburg: A Case Study〈/a〉〈br〉(Donaldson, S. E., Kotze, N. J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0078.pdf"〉Intra-Urban Distribution of Ethnic Minorities in Munich and Duisburg〈/a〉〈br〉(Yamamoto, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0083.pdf"〉New Urban Poverty in the Basque Country and Navarra〈/a〉〈br〉(Ferrer, M., d’Entremont, A., Ciscar, I., Saracibar, M. A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0085.pdf"〉Polarization and the Dutch Welfare State. The Case of Amsterdam〈/a〉〈br〉(Ostendorf, W., Musterd, S.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0088.pdf"〉III. Informal Economy〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0089.pdf"〉The Labour Market and the Role of Informality in Urban Mexico〈/a〉〈br〉(Aguilar, A. G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0092.pdf"〉The Informal Economy in Chinese Cities〈/a〉〈br〉(Qi, S. D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0093.pdf"〉The Urban Informal Sector: A Third World Experience〈/a〉〈br〉(Geeta Reddy, A., Rajkumar, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0094.pdf"〉Informal Urban Economy in the Lake Chad Basin〈/a〉〈br〉(Simeu-Kamdem, M.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0095.pdf"〉IV. Recent Urban Processes〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0096.pdf"〉City Challenge: Involving the Community in UK Urban Policy? 〈/a〉〈br〉(Lewis, J. R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0098.pdf"〉Intra-Metropolitan Relocation of Work Places: The Case of Stockholm〈/a〉〈br〉(Mahieu, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0102.pdf"〉Problems of Mobility and Traffic in the Ruhr〈/a〉〈br〉(Lötscher, L., Fleisgarten, S.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0103.pdf"〉Moscow 1993: The Emergence of Housing Market and the Problems of Intra-Urban Segregation〈/a〉〈br〉(Vendina, O. I.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0107.pdf"〉V. Urban Marketing, City Management, Urban Identity〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0108.pdf"〉Urban Marketing: A Review〈/a〉〈br〉(Borchert, J. G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0109.pdf"〉Urban Identity, City Image and Urban Marketing〈/a〉〈br〉(Dematteis, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0110.pdf"〉The Hidden Faces of the City〈/a〉〈br〉(Racine, J.-B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0111.pdf"〉The City of Bergen. Image and Marketing〈/a〉〈br〉(Sjøholt, P.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0113.pdf"〉Structural Underpinnings of an Olympic City Bid〈/a〉〈br〉(Davies, R. J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0116.pdf"〉Double Cities: Identity and Marketing of a New Urban Product〈/a〉〈br〉(Buursink, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0118.pdf"〉Corporate Space and Emerging Spatial Order in Japan〈/a〉〈br〉(Fujita, N.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0125.pdf"〉The Development of International Tourism in Tallinn, Estonia〈/a〉〈br〉(Kuus, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0126.pdf"〉Conflict, Consent, Cooperation: Comprehensive Planning in Germany Beyond Market and State〈/a〉〈br〉(Helbrecht, I.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0127.pdf"〉Urban Strategies: Mega Events. A Copenhagen Perspective〈/a〉〈br〉(Thor Andersen, H., Wichmann Matthiessen, C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0129.pdf"〉From Spaces of Planning to Places of Resistance〈/a〉〈br〉(Haarni, T.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0132.pdf"〉VI. Re-Cycling Urban Landscape〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0133.pdf"〉The Role of Gentrification in the Changing Ecology of Income: Evidence From Canadian Cities and Implications for Further Research〈/a〉〈br〉(Bourne, L. S.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0134.pdf"〉Gentrification and the Youth Movements of the 1960s〈/a〉〈br〉(Ley, D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0135.pdf"〉Recycling Urban Landscapes - Beyond the Power〈/a〉〈br〉(Andersson, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0136.pdf"〉Why was the Central City Population Stabilized? The Case of Copenhagen〈/a〉〈br〉(Illeris, S.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0138.pdf"〉Toronto's Underground City: Excavating the Terms of Access〈/a〉〈br〉(Hopkins, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0140.pdf"〉The Interpretation of Sea in Urban Planning and Everyday Life: The Case of Helsinki〈/a〉〈br〉(Karvinen, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0141.pdf"〉Urban Destinies - What are the Trends?〈/a〉〈br〉(Wärneryd, O.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0142.pdf"〉VII. Urban Modelling〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0143.pdf"〉DUVA – A Concept for a Metadata Driven Statistical Production and Information System〈/a〉〈br〉(Kopp, N.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0145.pdf"〉A New Era for Urban Modelling?〈/a〉〈br〉(Pumain, D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0146.pdf"〉Competing Order Parameters in a Self-Organizing City〈/a〉〈br〉(Portugali, J., Benenson, I.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0150.pdf"〉Authors and Addresses〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0151.pdf"〉[Werbung]〈/a〉〈/li〉 〈/body〉 〈/html〉

Beschreibung: conference

Beschreibung: DFG, SUB Göttingen

Beschreibung: Since the 14th century, moderate seismic activity with 14 earthquakes of magnitude MW≥5.0 occurred in Western Europe in a region extending from the Lower Rhine Graben (LRG) to the southern North Sea. In this paper, we investigate how well this seismic activity could reflect that of the future. The observed earthquake activity in the LRG is continuous and concentrates on the Quaternary normal faults delimiting the LRG, which are also the source of large surface rupturing Holocene and Late Pleistocene earthquakes. The estimated magnitudes of these past earthquakes range from 6.3±0.3 to 7.0±0.3 while their average recurrence on individual faults varies from ten thousand to a few ten thousand years, which makes foreseeing future activity over the long-term possible. Three of the largest historical earthquakes with MW≥5.5 occurred outside the LRG. Late Quaternary activity along the fault zones suspected to be the source of two of these earthquakes, i.e. the 1580 Strait of Dover and 1692 northern Belgian Ardennes earthquakes, is very elusive if it exists. Hence, similar earthquakes would be very infrequent at these locations suggesting that the seismicity outside of the LRG would be episodic and clustered on some faults during periods of a few hundreds of years interrupted by long periods of inactivity typically lasting for some tens to hundreds of thousand years. Seismic moment release estimation and its comparison between recent geological and historical seismicity periods lead us to suggest that the high seismicity level observed between AD 1350 and AD 1700 west of the LRG would be uncommon.

Beschreibung: research

Beschreibung: In the weekly newspaper of Osnabrück (Germany) of November 3, 1770, a report about a local earthquake was published. Pastor Buck described ground motion effects in the manor ‘Haus Horst’, 1.5 km away from the village of Alfhausen: ‘roof tiles rattled, a chimney fell down, inside the house the top of a stove was overturned, abraded chalk trickled down in all rooms; in the nearby villages, people felt the shaking, and especially the churches suffered noticeably’. The epicentral intensity was estimated to VII (MSK) by Ahorner et al. (1970), but later modified to VI (EMS) by Meier & Grünthal (1992) considering Buck’s report in detail. Since this event is the only documented earthquake in this region, a reliable characterization of its parameters is important. Our re-examination reveals that some reported effects are quite contradictory. Contrary to Buck’s statement, no documents of damages on churches or costs of repairs could be found in the parish registers. As a result, the event appears to be a tectonic earthquake with an epicenter at Alfhausen / Haus Horst. Applying intensity-attenuation relationships, a revised value of the epicentral intensity of I_0≤V (EMS-98) with a focal depth of z≥2 km was derived. A cavity collapse due to leaching processes as a cause of the effects can be ruled out here. However, several details given in the primary source turned out to be unrealistic or at least exaggerated. The tectonic earthquake on September 3, 1770 near Alfhausen should be classified therefore as uncertain or even doubtful.

Beschreibung: research