ALBERT

Description: Gephart and Forsyth's method has been applied to estimate stress orientations from earthquakefa ult planes olutionso f the southwesterAn lps, a regionw heret he tectonic stress regime is known to be fairly complex. Fault plane solutions have been either taken from the literature or computed using data from local and regional networks. Data refer to seismiecv entso f magnitudien the range2 .5-5.3w hicho ccurreidn the iastd ecades at depths between 0 and 25 km. Two zones with a different stress orientation have been identifiedi n the studieda rea (44.0ø-45.ø5 N, 6.5ø-8.5ø E)- the westernz one,c orresponding to the cresto f the alpine belt, where a high-dipm aximumc ompressivset ressi s found, and the easternz one (Alps chaint o Po Plain transition),c haracterizedb y an almosth orizontal E-W al and a nearly vertical as. Hypocenterso f earthquakesu sedf or stressi nversionl ie in the depthr anges0 -15 km and 5-25 km in the westerna nd easternz onesr, espectivelyT. he transitionb etweenth e two st•resdso mainsis very sharp,a nd this is alsoi ndicatedb y sp•ace distributiono f earthquakei ndividualm isfitst o the respectives tressm odels.T he findings of the present study are a good match for tectonic models which assume E-W compression derivedf rom the Adria-Europein teractiona nd producing:( 1) major thrustingp rocesses in the easterns ideo f the chaina nd (2) secondaryte nsionale ffectsa t very shallowd epth beneatht he alpineb elt crest( westernz oneo f the area studiedi n this work).

Description: Published

Description: 8171-8185

Description: 4T. Sismicità dell'Italia

Description: JCR Journal

Description: The sources and sinks of stratospheric reactive nitrogen (NOy) in the Antarctic are known only qualitatively, because of the very few measurements of NOy available in this region. As a result, the effects of stratospheric NOy short- and long-term changes on the stratospheric concentration of ozone, water vapor, and other climate-forcing agents are still uncertain. To better understand the annual cycle of polar stratospheric NOy, we estimate its concentration in the Antarctic stratosphere during part of 1993 and throughout 1995. These estimates are obtained at seven potential temperature levels, extending from 18 to 30 km of altitude, and are associated with ground-based measurements of another tracer, N2O, in order to produce NOy-N2O correlation curves that can provide insights on nitrogen sources and sinks. To estimate NOy mixing ratios, we use ground-based and satellite measurements of major NOy constituents, connected by using air parcel trajectories and supplemented by model calculations of minor contributing species for which no suitable measurements exist. All the available NOy-N2O correlation points are averaged over three representative seasonal time periods in 1993 and six periods in 1995. Results show very similar correlation curves during the late summer and the fall of 1995, and again during the early spring 1993 compared with the early and late winter of 1995, although there are large seasonal changes due to transport and to condensation of NOy onto polar stratospheric clouds. We calculate a loss from the latter process of N = (6.3 ± 2.6) 107 kg of stratospheric nitrogen in the southern polar vortex during 1995.We also compare our correlation curves with those obtained in the Antarctic stratosphere during the Atmospheric Trace Molecule Spectroscopy mission ATMOS/ATLAS-3 in November 1994, finding important similarities but also critical differences that suggest that extravortex air is generally not an adequate representation of prewinter inner vortex conditions. Calculations of NOy winter removal in the Antarctic stratosphere which have used extra-vortex measurements as a surrogate for prewinter conditions may thus have underestimated true NOy removal. Our prewinter NOy estimates in the vortex core match values obtained by atmospheric models that incorporate upper atmospheric sources of NOy, supporting the belief that such sources have a significant effect on polar stratospheric NOy.

Description: Published

Description: 4428

Description: 5A. Ricerche polari e paleoclima

Description: JCR Journal

Description: The rheological properties of suspensions containing high solid fractions are investigated. Attention is focused on viscosity of silicate and magmatic melt systems. A general empirical equation which describes the relative viscosity of suspensions as a function of suspended solid fraction is proposed. In the limit of very dilute solid concentrations it reduces to the Einstein equation. The proposed relationship is satisfactorily applied to reproduce available experimental data relative to silicate melts. Moreover, the extrapolation of the model to very high concentrations is compared with experimental observations on partially‐melted granite.

Description: Published

Description: L22308

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: JCR Journal

Description: On 17 January 2002, the city of Goma was partly destroyed by two of the several lava flows erupted from a roughly N-S oriented fracture system opened along the southern flank of Mount Nyiragongo (Democratic Republic of Congo), in the western branch of the East African rift system. A humanitarian and scientific response was promptly organized by international, governmental, and nongovernmental agencies coordinated by the United Nations and the European Union. Among the different scientific projects undertaken to study the mechanisms triggering this and possible future eruptions, we focused on the isotopic (He, C, and Ar) analysis of the magmatic-hydrothermal and cold gas discharges related to the Nyiragongo volcanic system, the Kivu and Virunga region. The studied area includes the Nyiragongo volcano, its surroundings, and peripheral areas inside and outside the rift. They have been subdivided into seven regions characterized by distinct 3He/4He (expressed as R/Rair) ratios and/or d13C-CO2 values. The Nyiragongo summit crater fumaroles, whose R/Rair and d13C-CO2 values are up to 8.73 and from 3.5% to 4.0% VPDB, respectively, show a clear mantle, mid-ocean ridge basalt (MORB)-like contribution. Similar mantle-like He isotopic values (6.5–8.3 R/Rair) are also found in CO2-rich gas emanations (mazukus) along the northern shoreline of Lake Kivu main basin, whereas the 13dC-CO2 values range from 5.3% to 6.8% VPDB. The mantle influence progressively decreases in (1) dissolved gases of Lake Kivu (2.6–5.5 R/Rair) and (2) the distal gas discharges within and outside the two sides of the rift (from 0.1 to 1.7 R/Rair). Similarly, d13C-CO2 ratios of the peripheral gas emissions are lighter (from 5.9% to 11.6% VPDB) than those of the crater fumaroles. Therefore, the spatial distribution of He and C signatures in the Lake Kivu region is mainly produced by mixing of mantle-related (e.g., Nyiragongo crater fumaroles and/or mazukus gases) and crustal-related (e.g., gas discharges in the Archean craton) fluids. The CO2/3He ratio (up to 10 1010) is 1 order of magnitude higher than those found in MORB, and it is due to the increasing solubility of CO2 in the foiditic magma feeding the Nyiragongo volcano. However, the exceptionally high 40Ar*/4He ratio (up to 8.7) of the Nyiragongo crater fumaroles may be related to the difference between He and Ar solubility in the magmatic source. The results of the present investigation suggest that in this area the uprising of mantle-originated f luids seems strongly controlled by regional tectonics in relation to the geodynamic assessment of the rift. These fluids are mainly localized in a relatively small zone between Lake Kivu and Nyiragongo volcano, with important implications in terms of volcanic activity.

Description: Published

Description: B01205

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: JCR Journal

Description: Waters and dissolved gases collected along vertical profiles in the five basins (Main, Kabuno Bay, Kalehe, Ishungu, and Bukavu) forming the 485 m deep Lake Kivu (Democratic Republic of the Congo) were analyzed to provide a geochemical conceptual model of the several processes controlling lake chemistry. The measured horizontal and vertical variations of water and gas compositions suggest that each basin has distinct chemical features produced by (1) different contribution from long circulating fluid system containing magmatic CO2, responsible of the huge CO2(CH4)-rich reservoir hosted within the deep lake water; (2) spatial variations of the biomass distribution and/or speciation; and (3) solutes from water-rock interactions. The Kabuno Bay basin is characterized by the highest rate of magmatic fluid input. Accordingly, this basin must be considered the most hazardous site for possible gas outburst that could be triggered by the activity of the Nyiragongo and Nyamulagira volcanoes, located a few kilometers north of the lake.

Description: Published

Description: Q02005

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: JCR Journal

Description: Recent satellite geodetic measurements help to clearly define the velocity field in the Aegean-Anatolian area. The velocity field can be broadly characterized by anticlockwise rotation of this region relative to Eurasia, around a pole located at Lat. 32.73, Long. 32.03, north of the Egyptian shoreline. Studies of the fault kinematics in the region also provide information on the time evolution of the stress field. In this work, we model deformation in the Aegean-Anatolian region to better understand the tectonic origin of the observed stress and velocity fields. We found that the observed deformation pattern can be well reproduced by imposing simple boundary conditions including: (1) northward displacement of the Arabian plate, (2) locking of eastward motion in northwestern Greece and (3) suction force at the Hellenic trench. The observed variation in the stress field occurred at 0.9 Ma can be partially explained by a change in the activity of the North Anatolian fault.

Description: Published

Description: 2087-2090

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: A model is proposed to explain the spatial distribution of foreshocks of the June 17th 2000, M s 6.6 earthquake in the South Iceland Seismic Zone (SISZ) and the high stress drop of the mainshock. Fluids of magmatic origin, ascending at near-lithostatic pressure through a low permeability layer perturb the regional stress field, inhibiting fluid flow laterally, where a high strength asperity is left. The asperity is modeled as elastic, embedded within a medium with low effective rigidity. Regional stresses due to tectonic motions are perturbed by the presence of the asperity, enhancing the production of hydrofractures and foreshocks in the NW and SE quadrants and increasing considerably the shear stress within the asperity, leading to the NS striking mainshock.

Description: Published

Description: L24305

Description: 7T. Variazioni delle caratteristiche crostali e precursori sismici

Description: JCR Journal

Description: The distribution of the magnitudes of seismic events is generally assumed to be independent on past seismicity. However, by considering events in causal relation, for example mother-daughter, it seems natural to assume that the magnitude of a daughter event is conditionally dependent on the one of the corresponding mother event. In order to find experimental evidence supporting this hypothesis, we analyze different catalogs, both real and simulated, in two different ways. From each catalog, we obtain the law of triggered events' magnitude by kernel density. The results obtained show that the distribution density of triggered events' magnitude varies with the magnitude of their corresponding mother events. As the intuition suggests, an increase of mother events' magnitude induces an increase of the probability of having "high" values of triggered events' magnitude. In addition, we see a statistically significant increasing linear dependence of the magnitude means.

Description: Published

Description: 903–916

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: JCR Journal

Description: We present new ground-based measurements of polar stratospheric and mesospheric CO, made with a millimeter-wave spectrometer at Thule, Greenland (76.5 N, 68.7 W). Almost daily measurements were made between 17 January and 4 March 2002 and again between 5 January and 22 February 2003. We stress here the retrieval and analysis of CO mixing ratios in the 50–80 km altitude range, though it can be monitored at lower altitudes as well. Since CO exhibits a strong positive latitude gradient from the summer to the winter pole, it is an excellent tracer for poleward transport from lower latitudes. Moreover, the mixing ratio of CO increases rapidly from 40 km to at least 100 km at midlatitudes, providing a good tracer for high-altitude vertical transport as well. Our profiles indicate that in winter near the poles the CO mixing ratio decreases above 70 km because of subsidence of air and minimal high-altitude photoproduction at high latitudes. Our data also show large variations in mixing ratio and vertical distribution, yielding a good picture of stratospheric and mesospheric dynamics-induced changes on a scale of hours to days. These observations verify that CO serves as an excellent tracer of vortex-related dynamics in the 30–80 km altitude range, where other information, particularly above 40 km, may be sparse, unreliable, or nonexistent. Our results are in general agreement with analyses of 1991–1992 Improved Stratospheric and Mesospheric Sounder (ISAMS) satellite data by Lopez-Valverde et al. [1993, 1996] and by Allen et al. [1999, 2000]. We show the contrast between CO over the summer pole and CO over the winter pole with the aid of trial observations made at the South Pole during the austral summer of 1999–2000. Our Thule data indicate that large concentrations of CO generally exist in winter just outside the vortex boundary. The large rapid variations in vertical profile that are found in our data in 2002 appear to be well correlated with vortex position in the lower stratosphere. In 2003 this correlation appeared to be much weaker, but early 2003 was also a period of vortex splitting in the Arctic on three occasions during our observation period, accompanied by generally more complex vortex dynamics.

Description: Published

Description: D06105

Description: 5A. Ricerche polari e paleoclima

Description: JCR Journal

Description: Morphological and geological observations reveal that most Apenninic faults are highly segmented and that the majority of the fault segments are less than 10 km long. Although these faults have undergone numerous paleoseismological investigations, quantitative data remain crucially lacking for a large number of fault segments. Because such data are essential to understanding how these faults have ruptured and interacted in the past and how they might behave in the future, we investigated the Holocene seismic history of the Pizzalto normal fault, a 13 km long fault segment belonging to the Pizzalto-Rotella-Aremogna fault system in the Apennines. We collected 44 samples from the Pizzalto fault plane exhumed during the Holocene and analyzed the 36Cl and rare earth element (REE) contents. Together, the 36Cl and REE concentrations show that at least six events have exhumed 4.4 m of the fault scarp between 3 and 1 ka, with slip per event values ranging from 0.3 to 1.2 m. No major events have been detected over the last 1 kyr. The Rotella-Aremogna-Pizzalto fault system has a clustered earthquake behavior with a mean recurrence time of 1.2 kyr and a low to moderate probability (ranging from 4{\%} to 26{\%}) of earthquake occurrence over the next 50 years.

Description: Published

Description: 1983–2003

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: One of the most intriguing facets of the climate system is that it exhibits variability across all temporal and spatial scales; pronounced examples are temperature and precipitation. The structure of this variability, however, is not arbitrary. Over certain spatial and temporal ranges, it can be described by scaling relationships in the form of power laws in probability density distributions and autocorrelation functions. These scaling relationships can be quantified by scaling exponents which measure how the variability changes across scales and how the intensity changes with frequency of occurrence. Scaling determines the relative magnitudes and persistence of natural climate fluctuations. Here, we review various scaling mechanisms and their relevance for the climate system. We show observational evidence of scaling and discuss the application of scaling properties and methods in trend detection, climate sensitivity analyses, and climate prediction.

Description: The past provides evidence of abrupt climate shifts and changes in the frequency of climate and weather extremes. We explore the non‐linear response to orbital forcing and then consider climate millennial variability down to daily weather events. Orbital changes are translated into regional responses in temperature, where the precessional response is related to nonlinearities and seasonal biases in the system. We question regularities found in climate events by analyzing the distribution of inter‐event waiting times. Periodicities of about 900 and 1150 years are found in ice cores besides the prominent 1500‐years cycle. However, the variability remains indistinguishable from a random process, suggesting that centennial‐to‐millennial variability is stochastic in nature. New numerical techniques are developed allowing for a high resolution in the dynamically relevant regions like coasts, major upwelling regions, and high latitudes. Using this model, we find a strong sensitivity of the Atlantic meridional overturning circulation depending on where the deglacial meltwater is injected into. Meltwater into the Mississippi and near Labrador hardly affect the large‐scale ocean circulation, whereas subpolar hosing mimicking icebergs yields a quasi shutdown. The same multi‐scale approach is applied to radiocarbon simulations enabling a dynamical interpretation of marine sediment cores. Finally, abrupt climate events also have counterparts in the recent climate records, revealing a close link between climate variability, the statistics of North Atlantic weather patterns, and extreme events.

Description: The effect of freshwater sources on wintertime sea-ice CO2 processes was studied from the glacier front to the outer Tempelfjorden, Svalbard, in sea ice, glacier ice, brine and snow. March–April 2012 was mild, and the fjord was mainly covered with drift ice, in contrast to the observed thicker fast ice in the colder April 2013. This resulted in different physical and chemical properties of the sea ice and under-ice water. Data from stable oxygen isotopic ratios and salinity showed that the sea ice at the glacier front in April 2012 contained on average 54% of frozen-in glacial meltwater. This was five times higher than in April 2013, where the ice was frozen seawater. In April 2012, the largest excess of sea-ice total alkalinity (AT), carbonate ion ([CO32−]) and bicarbonate ion concentrations ([HCO3−]) relative to salinity was mainly related to dissolved dolomite and calcite incorporated during freezing of mineral-enriched glacial water. In April 2013, the excess of these variables was mainly due to ikaite dissolution as a result of sea-ice processes. Dolomite dissolution increased sea-ice AT twice as much as ikaite and calcite dissolution, implying different buffering capacity and potential for ocean CO2 uptake in a changing climate.

Description: Radiocarbon (14C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.

Description: First, we retune an algorithm based on empirical orthogonal functions (EOFs) for globally retrieving the chlorophyll a concentration (Chl‐a) of phytoplankton functional types (PFTs) from multisensor merged ocean color (OC) products. The retuned algorithm, referred to as EOF‐SST hybrid algorithm, is improved by: (i) using 23% more matchups between the updated global in situ pigment database and satellite remote sensing reflectance (Rrs) products, and (ii) including sea surface temperature (SST) as an additional input parameter. In addition to the Chl‐a of the six PFTs (diatoms, haptophytes, dinoflagellates, green algae, prokaryotes, and Prochlorococcus), the fractions of prokaryote and Prochlorococcus Chl‐a to total Chl‐a (TChl‐a), are also retrieved by the EOF‐SST hybrid algorithm. Matchup data are separated for low and high‐temperature regimes based on different PFT dependences on SST, to establish SST‐separated hybrid algorithms which demonstrate further improvements in performance as compared to the EOF‐SST hybrid algorithm. The per‐pixel uncertainty of the retrieved TChl‐a and PFT products is estimated by taking into account the uncertainties from both input data and model parameters through Monte Carlo simulations and analytical error propagation. The algorithm and its method to determine uncertainties can be transferred to similar OC products until today, enabling long‐term continuous satellite observations of global PFT products. Satellite PFT uncertainty is essential to evaluate and improve coupled ecosystem‐ocean models which simulate PFTs, and furthermore can be used to directly improve these models via data assimilation.

Description: “Artificial Intelligence for Cold Regions” (AI-CORE) is a collaborative project of the German Aerospace Center (DLR), the Alfred Wegener Institute (AWI), the Technical University Dresden (TU Dresden), and is funded by the Helmholtz Foundation since early 2020. The project aims at developing artificial intelligence methods for addressing some of the most challenging research questions in remote sensing of the cryosphere. Rapidly changing ice sheets and thawing permafrost are big societal challenges, hence quantifying these changes and understanding the mechanisms are of major importance. Given the vast extent of polar regions and the availability of exponentially increasing satellite remote sensing data, intelligent data analysis is urgently required to exploit the full information in satellite time series. This is where AI-CORE comes into play: Four geoscientific use cases have been defined, including a) change pattern identification of outlet glaciers in Greenland; b) object identification in permafrost areas; c) edge detection of calving fronts of glaciers/ice shelves in Antarctica; d) firn line detection and monitoring: The glacier mass balance indicator. For these four use cases, AI-methods are being developed to allow for an accurate, efficient, and automated extraction of the desired parameters. Once these methods have been successfully developed, they will be implemented in processing infrastructures at AWI, TU Dresden, and DLR, and subsequently made available to other research institutes. The presentation will outline the specific goals and challenges of the four use cases as well as the current state of the developments and preliminary results.

Description: Iron (Fe) plays a key role in mediating organic carbon (OC) decomposition rates in permafrost soils. Fe-bearing minerals stabilize OC through complexation, co-precipitation or aggregation processes and thus hinder degradation of OC. In addition, Fe(III) reduction can inhibit methanogenesis and decrease warming potential of greenhouse gases release. Ice-rich permafrost is subject to abrupt thaw and thermokarst formation, which unlocks OC and minerals from deep deposits and exposes OC to mineralization. These ice-rich domains include Yedoma sediments that have never thawed since deposition and Alas sediments that have undergone previous thermokarst processes during the Lateglacial and Holocene warming periods. The post-depositional history of these sediments may affect the distribution and reactivity of Fe-bearing minerals and the role Fe plays in mediating present day OC mineralization. Here we quantify Fe concentrations, Fe spatial and depth distribution, and Fe mineralogy in unthawed Yedoma and previously thawed Alas deposits from the Yedoma domain (West Siberia, Laptev Sea region, Kolyma region, New Siberian Islands and Alaska). Total Fe concentrations of ice-rich Yedoma deposits and previously thawed Alas deposits were determined using a portable X-ray fluorescence (XRF) device. This non-destructive method allowed a total iron concentration assessment of Yedoma domain deposits based on 1292 sediment samples. Portable XRF-measured concentrations trueness were calibrated from alkaline fusion and inductively coupled plasma optical emission spectrometry (ICP-OES) measurement method on a subset of 144 samples (R² = 0.81). Fe extractions of unthawed and previously thawed deposits display that, on average, 25% of the total iron is considered as reactive species, either as crystalline or amorphous oxides, or complexed with OC, with no significant difference between Yedoma and Alas deposits. We observe a constant total Fe concentration in Yedoma deposits, but a depletion or accumulation of total Fe in Alas deposits, which experienced previous thaw and/or flooding events, suggesting that redox driven processes during the Lateglacial and Holocene thermokarst formation impact the present day distribution of reactive Fe and its association with organic carbon in ice-rich permafrost.

Description: Thematic Open Access data portals foster and support an open data culture in order to reduce knowledge gaps and data uncertainty. Here we present the Arctic Permafrost Geospatial Center (APGC), which provides open access, high quality spatial data in the field of permafrost research. The distribution and easy access of a wide range of permafrost-related data products supports multi-scale and interdisciplinary analysis of combined field, remote sensing and modelling data. The APGC mission is to provide data that is of high usability, significance and impact, and to facilitate data discovery, data view and supports metadata documentation and exchange via the APGC data catalogue at https://apgc.awi.de/. The catalogue structure can host data models of varying themes, formats, and spatial and temporal extents. Data can be searched by interactively selecting locations on a base map and by many predefined metadata filters. Data can be downloaded directly through a link to the publishing data repository such as PANGAEA. The Catalogue is based on the open source CKAN catalogue architecture, which allows on-the-fly access to catalogued data in QGIS. The APGC currently features over 200 selected datasets from projects such as ERC PETA-CARB, ESA GlobPermafrost, and others. Data products provide information about surface and subsurface permafrost characteristics in the Arctic, Antarctica, or mountain permafrost areas, e.g., soil temperatures, soil carbon, ground ice, land cover, vegetation, periglacial landforms, subsidence and more. Collections of datasets allow users to easily get an overview of the spatial distributions of datasets or their availability in different formats. An additional WebGIS application allows users to explore most of the data interactively (https://maps.awi.de). Data submissions are evaluated according to the following access criteria: permafrost focus, broader significance and impact, open access, high quality, and available metadata.

Description: Lakes and drained lake basins (DLBs) are dominant landforms across Arctic lowland regions. The long-term dynamics of lake formation and drainage is evident in the abundance of lakes and DLBs covering as much as 80% of the landscape in various regions of Arctic Alaska, Russia, and Canada. Lake drainage can be triggered through different mechanisms such as lake tapping by an adjacent stream, bank overflow or ice wedge degradation. Following drainage, DLBs can become valuable grazing land for caribou and reindeer as well as usable land for infrastructure development due to low ground ice content in recent DLBs. In addition, DLBs can be sites for soil organic carbon accumulation in the form of peat which also play a role for carbon cycling. Comprehensive and accurate mapping of DLB distribution, age and drainage mechanism, will further inform our understanding of their role in permafrost landscape evolution across varying timescales. DLBs differ from the surrounding terrain in vegetation structure and composition, soil moisture, elevation, size and types of ice-wedge polygons and other parameters that make them an identifiable target based on remote sensing data. Here, we present a novel approach to map DLBs in permafrost landscapes with a specific focus on the North Slope of Alaska as well as select areas in Siberia and northwestern Canada. To map DLBs, we combined multispectral satellite imagery (Landsat-8 and Sentinel-2), Synthetic Aperture Radar (SAR) acquisitions (Sentinel-1), and DEM data (ArcticDEM). To cover the entire study area in each region, we included Landsat-8 acquisitions from all available years and Sentinel-2 for 2016 and 2018 to create cloud-free mosaics. The classification combines methodologies from pixel-based and object-based image analysis. To allow for processing of these large datasets that cover more than 200.000 km2, a classification workflow was developed in Google Earth Engine. Preliminary results show good agreement of our classification with previously published data sets for subsets of our North Slope study area. This work marks the first attempt to map DLBs at the pan-Arctic scale. Our results highlight the importance of treating areas of different surficial geology and vegetation communities separately in the classification process to ensure higher classification accuracy.

Description: Uncertainty in carbon cycling in terrestrial ecosystems contributes to overall uncertainty in Earth System Models. In particular, polar terrestrial ecosystems are understudied. Here, we focus on optical and radar remote sensing approaches to understand above-ground carbon dynamics related to vegetation as primary producers in tundra permafrost landscapes. In the ongoing Russian-German research cooperation and joint field expeditions we evaluate the applicability of remote sensing for assessing vegetation stocks and short-term fluxes in the Lena River Delta in the Siberian Arctic. New spaceborne satellite missions such as Sentinel-1, Sentinel-2 and ESA Data User Element DUE Permafrost provide useful services and data for this investigation. i) We evaluated and ground-truthed circumarctic-harmonized geospatial products of land cover and vegetation height from the ESA GlobPermafrost program for the Lena Delta region. The remote sensing products were derived from radar Sentinel-1 and optical Sentinel-2 satellite data. They are findable in the Arctic Permafrost Spatial Center (APGC) (apgc.awi.de) and are published under 10.1594/PANGAEA.897916, [Titel anhand dieser DOI in Citavi-Projekt übernehmen] and 10.1594/PANGAEA.897045 [Titel anhand dieser DOI in Citavi-Projekt übernehmen] . ii) We classified land cover using Sentinel-2 data based on in-situ vegetation data and optimized on biomass and wetness regimes. iii) We investigated the applicability of different land cover products for upscaling in-situ field-based biomass estimates to landscape-scale above-ground vegetation carbon stocks. iv) We investigated how disturbances enhance above-ground vegetation carbon cycling using in-situ data on vegetation community, biomass, and stand age and including remote sensing observations. Our research suggests that subarctic land cover needs to show biomass and moisture regimes to be applicable. Sentinel-1 and Sentinel-2 satellite missions provide adequate spatial high resolution to upscale vegetation communities and biomass in permafrost tundra landscapes. Biomass is providing the magnitude of the carbon flux, whereas stand age is irreplaceable to provide the cycle rate. High disturbance regimes such as floodplains, valleys, and other areas of thermo-erosion are linked to high and rapid carbon fluxes compared to low disturbance on Yedoma upland tundra and holocene terraces with polygonal tundra.

Description: Increased ocean‐to‐ice heat fluxes play a key role in the accelerated mass loss of Greenland’s marine‐terminating glaciers. Ocean current variability leads to variations in this heat flux. A year‐long time series of ocean currents at all gateways to the ocean cavity under Greenland’s largest remaining floating ice tongue at the Nioghalvfjerdsfjorden Glacier (79NG) was analyzed. The variability of the exchange flow at intra‐annual to near‐daily timescales was characterized. The currents exhibit considerable variability with standard deviations exceeding the time mean flow strength by a factor of 2. The inflow of warm Atlantic Intermediate Water into the cavity and the outflow via the northernmost calving front were directly coupled on intra‐annual timescales (periods, T 〉 30 days) with enhanced fluctuations in the winter months. A strong correlation between the variability of the deep inflow and currents in the subsurface boundary current on the continental shelf suggests a link between cavity and continental shelf circulation. Variability on higher frequencies (T 〈 30 days) in the outflow was only partly induced by the inflow variability. Two export branches of the cavity circulation were identified, which were potentially constrained by subglacial meltwater channels. The relative importance of the two export branches varies on monthly time scales. This research has provided evidence that the large intra‐annual ocean current variability at the 79NG is strongly influenced by the continental shelf circulation. Temporally varying preferred export routes increase the complexity of the cavity circulation.

Description: High-resolution seafloor mapping provides insights into the dynamics of past ice sheets/ice shelves on high-latitude continental margins. Geological/geophysical studies in the Arctic Ocean suggest widespread Pleistocene ice grounding on the Chukchi–East Siberian continental margin. However, flow directions, timing, and behavior of these ice masses are not yet clear due to insufficient data. We present a combined seismostratigraphic and morphobathymetric analysis of the Chukchi Rise off the northwestern Chukchi margin using the densely acquired subbottom profiler (SBP) and multibeam echosounder (MBES) data. Comparison with deeper airgun seismic records shows that the SBP data cover most of the glaciogenic stratigraphy possibly spanning ca. 0.5–1Ma. Based on the stratigraphic distribution and geometry of acoustically transparent glaciogenic diamictons, the lateral and vertical extent of southern- sourced grounded ice became smaller over time. The older deposits are abundant as debris lobes on the slope contributing to a large trough mouth fan, whereas younger grounding-zone wedges are found at shallower depths. MBES data show two sets of mega-scale lineations indicating at least two fast ice- streaming events of different ages. Contour-parallel recessional morainic ridges mark a stepwise retreat of the grounded ice margin, likely controlled by rising sea levels during deglaciation(s). The different inferred advance and retreat directions of the southern-sourced ice reflect complex geomorphic settings. The overall picture shows that the Chukchi Rise was an area where different ice streams had complex interactions. In addition to glaciogenic deposits, we identify a number of related or preceding seabed features including mounds, gullies/channels, and sediment waves.

Description: We present a series of simple shear numerical simulations of dynamic recrystallization of two‐phase non‐linear viscous materials that represent temperate ice. Firstly, we investigate the effect of the presence of water on the resulting microstructures and, secondly, how water influences on P‐wave (Vp) and fast S‐wave (Vs) velocities. Regardless the water percentage, all simulations evolve from a random fabric to a vertical single maximum. For a purely solid aggregate, the highest Vp quickly aligns with the maximum c‐axis orientation. At the same time, the maximum c‐axis development reduces Vs in this orientation. When water is present, the developed maximum c‐axis orientation is less intense, which results in lower Vp and Vs. At high percentage of water, Vp does not align with the maximum c‐axis orientation. If the bulk modulus of ice is assumed for the water phase (i.e., implying that water is at high pressure), we find a remarkable decrease of Vs while Vp remains close to the value for purely solid ice. These results suggest that the decrease in Vs observed at the base of the ice sheets could be explained by the presence of water at elevated pressure, which would reside in isolated pockets at grain triple junctions. Under these conditions water would not favor sliding between ice grains. However, if we consider that deformation dominates over recrystallization water pockets get continuously stretched, allowing water films to be located at grain boundaries. This configuration would modify and even overprint the maximum c‐axis‐dependent orientation and the magnitude of seismic anisotropy.

Description: Beyond ~13.9 cal kBP, the IntCal20 radiocarbon (14C) calibration curve is based upon combining data across a range of different archives including corals and planktic foraminifera. In order to reliably incorporate such marine data into an atmospheric curve, we need to resolve these records into their constituent atmospheric signal and marine reservoir age. We present results of marine reservoir age simulations enabling this resolution, applying the LSG ocean general circulation model forced with various climatic background conditions and with atmospheric radiocarbon changes according to the Hulu Cave speleothem record. Simulating the spatiotemporal evolution of reservoir ages between 54,000 and 10,700 cal BP, we find reservoir ages between 500 and 1400 yr in the low- and mid-latitudes, but also more than 3000 yr in the polar seas. Our results are broadly in agreement with available marine radiocarbon reconstructions, with the caveat that continental margins, marginal seas, or tropical lagoons are not properly resolved in our coarse-resolution model.

Description: The concentration of radiocarbon (14C) differs between ocean and atmosphere. Radiocarbon determinations from samples which obtained their 14C in the marine environment therefore need a marine-specific calibration curve and cannot be calibrated directly against the atmospheric-based IntCal20 curve. This paper presents Marine20, an update to the internationally agreed marine radiocarbon age calibration curve that provides a non-polar global-average marine record of radiocarbon from 0–55 cal kBP and serves as a baseline for regional oceanic variation. Marine20 is intended for calibration of marine radiocarbon samples from non-polar regions; it is not suitable for calibration in polar regions where variability in sea ice extent, ocean upwelling and air-sea gas exchange may have caused larger changes to concentrations of marine radiocarbon. The Marine20 curve is based upon 500 simulations with an ocean/atmosphere/biosphere box-model of the global carbon cycle that has been forced by posterior realizations of our Northern Hemispheric atmospheric IntCal20 14C curve and reconstructed changes in CO2 obtained from ice core data. These forcings enable us to incorporate carbon cycle dynamics and temporal changes in the atmospheric 14C level. The box-model simulations of the global-average marine radiocarbon reservoir age are similar to those of a more complex three-dimensional ocean general circulation model. However, simplicity and speed of the box model allow us to use a Monte Carlo approach to rigorously propagate the uncertainty in both the historic concentration of atmospheric 14C and other key parameters of the carbon cycle through to our final Marine20 calibration curve. This robust propagation of uncertainty is fundamental to providing reliable precision for the radiocarbon age calibration of marine based samples. We make a first step towards deconvolving the contributions of different processes to the total uncertainty; discuss the main differences of Marine20 from the previous age calibration curve Marine13; and identify the limitations of our approach together with key areas for further work. The updated values for ΔR, the regional marine radiocarbon reservoir age corrections required to calibrate against Marine20, can be found at the data base http://calib.org/marine/.

Description: Permafrost coasts make up roughly one third of all coasts worldwide. Their erosion leads to the release of previously locked organic carbon, changes in ecosystems and the destruction of cultural heritage, infrastructure and whole communities. Since rapid environmental changes lead to an intensification of Arctic coastal dynamics, it is of great importance to adequately quantify current and future coastal changes. However, the remoteness of the Arctic and scarcity of data limit our understanding of coastal dynamics at a pan-Arctic scale and prohibit us from getting a complete picture of the diversity of impacts on the human and natural environment. In a joint effort of the EU project NUNATARYUK and the NSF project PerCS-Net, we seek to close this knowledge gap by collecting and analyzing all accessible high-resolution shoreline position data for the Arctic coastline. These datasets include geographical coordinates combined with coastal positions derived from archived data, surveying data, air and space born remote sensing products, or LiDAR products. The compilation of this unique dataset will enable us to reach unprecedented data coverage and will allow us a first insight into the magnitude and trends of shoreline changes on a pan-Arctic scale with locally highly resolved temporal and spatial changes in shoreline dynamics. By comparing consistently derived shoreline change data from all over the Arctic we expect that the trajectory of coastal change in the Arctic becomes evident. A synthesis of some initial results will be presented in the 2020 Arctic Report Card on Arctic Coastal Dynamics. This initiative is an ongoing effort – new data contributions are welcome!

Description: The importance of volcanic CO2 release, continental weathering and coral reef growth on the global carbon cycle has been highlighted by several different studies. Based on these independent approaches we here revisit the last 800 kyr with the box model BICYCLE, which has been extended by a process based sediment module to be able to address these solid Earth contributions to the carbon cycle in detail. We show, that the volcanic outgassing of CO2 as function of sea level change from mid ocean ridges and hot spot island volcanoes cannot be the generic process that leads during phases of falling obliquity to a sea level-CO2 decoupling as has been suggested before. The combined contribution from continental and marine volcanism, if both lagging sea level change by 4 kyr, might have added up to 13 ppm to the glacial/interglacial CO2 rise. The shallow water carbonate sink related to coral reef growth as suggested by an independent model are dur- ing glacial terminations about an order of magnitude too high to be reconciled with meaningful carbon cycle dynamics. Global riverine input of bicarbonate caused by silicate and carbonate weathering is suggested to have been stable over Termination I. However, if weathering fluxes are changed by up to 50% in sensitivity experiments the corresponding bi- carbonate input might contribute less than 20 ppm to the deglacial atmospheric CO2 rise. The overall agreement of re- sults with the new process-based sediment module and the previously applied time-delayed response function to mimic carbonate compensation gives confidence in the results obtained in previous applications of the BICYCLE model without solid Earth processes.

Description: Southern Ocean westerly wind intensity and position are thought to play a crucial role in controlling glacial/interglacial CO2 changes through their impact on Antarctic upwelling intensity and the delivery of iron-rich dust that stimulates biological production during glacial periods. Sediment-core grain size records can provide key insights into changes in wind strength and source-area characteristics over glacial-interglacial timescales. However, so far, little is known about G/IG grain size changes in Southern Ocean sediments. For this study, we analyzed the grain-size distributions of two subantarctic deep sea sediments cores from the Pacific (PS75/056-1) and Atlantic (ODP Site 1090) sectors of the Southern Ocean. Dust mean grain size shows opposing trends in the two Southern Ocean sectors. Coarser glacial grain sizes are observed in the Pacific sector, while finer glacial grain-sizes are observed in the Atlantic. Our results suggest that changes in the latitudinal position of the SWW had distinct impacts on grain size distribution in the Atlantic and Pacific sectors, also likely associated with shifts in the dust source areas. These findings indicate that more extensive studies of grain-size distribution in the Southern Ocean can provide important insights on the timing and latitudinal extent of the westerly winds changes during ice ages.

Description: Ebullition (bubbling) is often the dominant form of methane (CH4) emission from Arctic lakes. Understanding the dynamics of CH4 ebullition in these lakes is important to the global atmospheric CH4 budget and climate models. Lake CH4 ebullition bubbles generally originate from either ecologic or geologic sources. Ecologic CH4 is produced through anaerobic microbial decomposition of organic matter within lake sediments and the talik - a thawed zone beneath lakes in permafrost regions. Emissions from these seeps can be quantified and scaled based on existing field-based and remote-sensing methods. The other type of ebullition has not been well quantified, yet emits gas at a much higher rate than ecologic seeps. Geologic CH4 seeps originate from microbial, thermogenic, or a combination of both processes altering buried organics in ancient sedimentary basins. Bubbling rates of geologic seeps are strong enough to maintain holes in thick (〉1 m) lake ice – creating winter traveling hazards in the Arctic and sub-Arctic. While ecologic CH4 seeps produced in surficial sediments have modern to Holocene radiocarbon (14C) ages and those produced deeper in the talik have Pleistocene to early Holocene 14C ages, geologic CH4 seeps are often 14C-depleted due to the large contribution of carbon from fossil sources. Quantification and upscaling of geologic CH4 seepage is challenging because CH4 accumulations are distributed beneath complex, site-specific geologic and cryospheric settings. Previously, geologic seeps were studied through aerial surveys and ground truthing of open holes in winter lake ice along a north-south Alaskan transect. However, this is not efficient for quantifying these “superseeps” on a larger scale. Therefore, a remote sensing approach is needed. This work aims to detect superseeps using space borne Synthetic Aperture Radar (SAR). Engram et al. (2013) showed that L-band SAR backscatter correlates with roughness caused by stratigraphically-layered ecologic CH4 bubbles trapped during freeze-up – the greater the ebullition, the stronger the backscatter. Using this correlation, we developed a new method that identifies superseeps as perennial backscatter anomalies in lake ice on a landscape scale. Results from three regions in Alaska will be presented and compared to other methods of studying superseeps.

Description: Permafrost thaw has been observed at several locations across the pan-Arctic in recent decades, yet the pan-Arctic extent and potential spatial-temporal variations in thaw are poorly constrained. Thawing of ice-rich permafrost can be inferred and quantified with satellite imagery due to the subsequent differential ground subsidence and erosion that in turn affects land surface cover. Information contained within existing and rapidly growing collections of high-resolution satellite imagery (Big Imagery) is here extracted across the Arctic region through a collaboration between software engineers, computer- and earth scientists. More specifically, we are a) developing geospatial data down to sub-meter resolution, and also b) enabling discovery and knowledge-generation through visualization tools. This cyberinfrastructure platform, the Permafrost Discovery Gateway (PDG), is being designed with input from users of the PDG, e.g. primarily the Arctic earth science community but also the general public. The PDG builds upon other NSF supported data management resources (Arctic Data Center and Clowder) and the Fluid Earth Viewer. The Fluid Earth Viewer, which is the first visualization tool implemented into the PDG, was initially created for the public to explore atmospheric and oceanographic visualizations and is here modified to support permafrost geospatial products, and a number of community built analytic tools to identify permafrost artifacts within satellite imagery. The effort also includes workflow optimization of remote sensing code for pan-Arctic sub-meter scale mapping of ice-wedge polygons from optical imagery. We are additionally actively engaging with the user-community to ensure that the PDG becomes useful, both in terms of the type of data contained within the PDG and the design of the visualization tools. The PDG has the potential to fill key Arctic science gaps, such as bridging plot to pan-Arctic scale findings, while also serving as a resource informing decisions regarding the economy, security, and resilience of the Arctic region.

Description: While increasing Arctic temperatures have been identified to induce widespread thermokarst development in permafrost lowland landscapes over only several decades, disturbances, such as tundra fires can cause similar impacts within a few years. Transition from low-centered to high-centered polygons through the formation of troughs is an immediate result of melting ice wedges 3-4 years after a fire (Jones et al., 2015). Liljedahl et al (2016) have shown that widespread ice-wedge degradation can lead to hydrological connectivity and increased drainage of entire landscapes through newly developing trough networks. Quantifying such dynamics is important for projecting the hydrological outcomes of climate change impacts across vast Arctic landscapes. New VHR remote sensing approaches allow assessing ice wedge polygonal structures and their change in unprecedented detail. Data science methods provide valuable tools for understanding and modeling resulting very large datasets of changing ice wedge networks. Here we quantify thermokarst development representing the network of troughs as a graph, a concept from discrete mathematics used to model complex networks. Our analysis is based on optical VHR aerial imagery of the DLR MACS sensors and DSMs derived from LiDAR. Datasets are available for 2009, 2014 and 2019 of the northern Anaktuvuk River Fire scar in Alaska, which formed due to a large tundra fire in 2007. In particular, the post-fire permafrost degradation is observable in the northern ice-rich region of the fire scar on short timescales, offering an ideal site for the monitoring of degradation processes. We use morphological image analysis to extract a graph from the imagery and further deduce trough parameters, such as soil volume, depth, and water availability. Quantifying these factors for the study area shows that soil erosion and ice melt within individual troughs have progressed, while the overall connectivity of the network has increased, implying strong thermo-erosion since 2009. Using graphs to monitor the ongoing development offers a detailed and computationally efficient method that will allow quantification of ice-wedge degradation over very large spatial and temporal scales and may provide useful metrics for projecting landscape trajectories in thaw-vulnerable permafrost environments.

Description: The importance of non-growing season greenhouse gas fluxes to annual budgets in pristine northern terrestrial ecosystems is growing in awareness. Greenhouse gas (GHG) fluxes during the non-growing season and freeze-thaw dynamics are still underrepresented and may be a reason why current process-based models predict inadequate annual methane (CH4) and nitrous oxide (N2O) budgets. FluxWIN is therefore investigating ecological and biogeochemical processes in global carbon (C) and nitrogen (N) cycles during the non-growing and shoulder seasons by combining high-frequency greenhouse gas measurements, biogeochemical monitoring and process-based modeling. Siikaneva, nearby Hyytiälä Research Station in boreal Finland, is an ICOS-certified site and well situated within long-term scientific infrastructure to compare and combine high-frequency greenhouse gas measurement techniques and investigate freeze-thaw dynamics. An automated static chamber technique is used with inline laser gas analysis to obtain soil-atmosphere CH4 and N2O exchange in real time. Additional automated sampling of diffusion tubing will sample soil gas concentrations in the same analytical system. We control for climatic variability and isolate differences in non-growing season emissions by using a moisture gradient from well-drained upland soils to adjacent wetland ecosystems. The use of these automated high-frequency GHG measurements in combination with year-round biogeochemical monitoring maximizes the likelihood of capturing episodic emissions and their drivers, which are particularly important during fall freeze and spring thaw periods. The gained information on ecosystem function and biogeochemical cycles for temperate, boreal, and arctic regions will improve feedback estimates to climate change by including non-growing season processes in global-scale process-based models.

Description: Currently, the most rapid increase in near-surface air temperature takes place in the Arctic, accompanied by reduced sea ice concentration. Under the resulting retreat of sea ice, the underwater shortwave radiation and, thus, the amount and types of phytoplankton may change. In this study, we use a coupled sea-ice – ocean – ecological model (Darwin-MITgcm) to simulate the variability of the ocean’s major optically active constituents, comprising six phytoplankton functional types (PFTs) and colored dissolved organic matter (CDOM), in response to Arctic amplification. We further set up the general circulation model to account for the biogeochemical processes, in terms of light attenuation, so that their feedback on Arctic Ocean’s physical and biogeochemical properties can be assessed. Here, for the first time, CDOM is included in the underwater light attenuation scheme as a prognostic model variable that interacts with the changes induced by its presence. The coupled model simulation, allowing to consider explicitly the optical constituents, is compared with a constant attenuation depth formulation corresponding to Jerlov water type I, which is the case in most ocean models. Our findings suggest that the presence of CDOM and phytoplankton, by modulating the vertical distribution of the incoming light, affects significantly the upper ocean thermal structure. The promotion of heat-trapping near the surface results in summertime warming, locally even in more than 1°C, and to sea ice reduction. These changes have implications to upper ocean stratification and are accompanied by changes in nutrients supply, as well as in total but also partial PFTs chlorophyll-a.

Description: The distribution, density and percentage contribution of pack ice seals during ship-board censuses in the marginal sea ice zone beyond the Lazarev Sea in spring 2019 are presented. Adult/juvenile crabeater seals (n = 19), leopard seals (n = 3) and Ross seals (n = 10) were sighted during 582.2 nm of censuses along the ship’s track line in the area bounded by 00°00’–22°E and 56°–60°S. Antarctic fur seals (n = 21) were only encountered on the outer fringes of the pack ice, and Weddell seals were absent due to their primary use of fast ice and inner pack ice habitats close to the coast. Crabeater seal sightings included juveniles (n = 2) and another four groups of 2–3 unclassified crabeater seals, singletons (n = 5), single mothers with pups (n = 3) and a family group (n = 1 triad). Only one leopard seal attended a pup, while no Ross seal pups were located. The survey was likely of insufficient effort, in both extent (north of 60°S) and duration (18 days), to locate seals in considerable numbers this early (late October/early November) in their austral spring breeding season.

Description: We investigate the upper mantle discontinuities in the central Mediterranean region by applying the P and S receiver function techniques on waveforms recorded at broadband stations located around the Tyrrhenian basin. P and S wave velocity profiles (down to 300‐km depth) are calculated with joint inversion of P and S receiver functions. We could identify the Moho, lithosphere‐asthenosphere boundary, and an underlying low‐velocity layer between ~60‐ and ~200‐km depth. The low‐velocity layer is interpreted as asthenospheric material, and its lower boundary is identified below the western Ionian and Tyrrhenian basins as a sharp Lehmann discontinuity. Although the stations are located on different lithospheric domains we find a strong correlation between Moho and the lithosphere‐asthenosphere boundary depths, which suggests ubiquitous coupling of the crust and lithospheric mantle, consistently with the southward opening of the Tyrrhenian basin. The Tyrrhenian and western Ionian basins present thinning of the transition zone of ~14 km, as inferred from a reduced P660s‐P410s differential time. Below the southern Apennines we observe a standard differential time that implies an average mantle transition zone thickness. We explain these mantle transition zone thickness variations as due to temperature heterogeneity linked to the area's subduction history. Finally, under central Europe (the location of the deep S‐to‐P conversion points) two strong signals from nonstandard discontinuities within the mantle transition zone are observed. These signals can be explained as being generated at the boundaries of high seismic velocity layers that are spatially correlated with stagnant slabs in the transition zone detected by seismic tomography.

Description: Published

Description: 4545-4566

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: Building resiliency to natural hazards like earthquakes requires worldwide engagement, starting from education and dissemination of good practice among the youths. Education of new professionals in the field of seismic risk takes nowadays advantage from the implementation of emergent technologies, such as Augmented Reality (AR) and Virtual Reality (VR), which can benefit from the huge amount of digital information available. We present a few case studies from two European projects promoting education and communication also throughout the application of AR and VR. Targeted audiences of the two projects were schools and universities. KnowRISK (Know your city, Reduce seISmic risK through non-structural elements; Grant agreement ECHO/SUB/2015/718655/PREV28) ended in 2018; it had a special focus on non-structural damage caused by earthquakes, exploring the causes of disruption and proposing preventive measures to reduce it. 3DTeLC is funded through the Erasmus+ Key Action 2 Strategic Partnerships for Higher Education scheme (Project Reference: 2017-1-UK01-KA203-036719) and will be completed in 2020. The project trains students to navigate 3D models of volcanic regions in Iceland, Greece, and Italy (at Mt. Etna volcano), allowing them to carry out virtual surveys also in hazardous contexts. Accordingly, the project aims at strengthening students’ skills in Earth observation and data analysis.

Description: Published

Description: San Francisco, CA, USA

Description: 2TM. Divulgazione Scientifica

Description: Volcanism and metamorphism are the principal geologic processes that drive carbon transfer from the interior of Earth to the surface reservoir.1–4 Input of carbon to the surface reservoir through volcanic degassing is balanced by removal through silicate weathering and the subduction of carbon-bearing marine deposits over million-year timescales. The magnitude of the volcanic carbon flux is thus of fundamental importance for stabilization of atmospheric CO2 and for long-term climate. It is likely that the “deep” carbon reservoir far exceeds the size of the surface reservoir in terms of mass;5,6 more than 99%of Earth’s carbon may reside in the core, mantle, and crust. The relatively high flux of volcanic carbon to the surface reservoir, combined with the reservoir’s small size, results in a short residence time for carbon in the ocean–atmosphere–biosphere system (~200 ka).7 The implication is that changes in the flux of volcanic carbon can affect the climate and ultimately the habitability of the planet on geologic timescales. In order to understand this delicate balance, we must first quantify the current volcanic flux of carbon to the atmosphere and understand the factors that control this flux.

Description: Published

Description: 188-236

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Reimer, P. J., Austin, W. E. N., Bard, E., Bayliss, A., Blackwell, P. G., Ramsey, C. B., Butzin, M., Cheng, H., Edwards, R. L., Friedrich, M., Grootes, P. M., Guilderson, T. P., Hajdas, I., Heaton, T. J., Hogg, A. G., Hughen, K. A., Kromer, B., Manning, S. W., Muscheler, R., Palmer, J. G., Pearson, C., van der Plicht, J., Reimer, R. W., Richards, D. A., Scott, E. M., Southon, J. R., Turney, C. S. M., Wacker, L., Adolphi, F., Buentgen, U., Capano, M., Fahrni, S. M., Fogtmann-Schulz, A., Friedrich, R., Koehler, P., Kudsk, S., Miyake, F., Olsen, J., Reinig, F., Sakamoto, M., Sookdeo, A., & Talamo, S. The Intcal20 Northern Hemisphere radiocarbon age calibration curve (0-55 cal kBP). Radiocarbon, 62(4), (2020): 725-757, doi:10.1017/RDC.2020.41.

Description: Radiocarbon (14C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.

Description: We would like to thank the National Natural Science Foundation of China grants NSFC 41888101 and NSFC 41731174, the 111 program of China (D19002), U.S. NSF Grant 1702816, and the Malcolm H. Wiener Foundation for support for research that contributed to the IntCal20 curve. The work on the Swiss and German YD trees was funded by the German Science foundation and the Swiss National Foundation (grant number: 200021L_157187). The operation in Aix-en-Provence is funded by the EQUIPEX ASTER-CEREGE, the Collège de France and the ANR project CARBOTRYDH (to EB). The work on the correlation of tree ring 14C with ice core 10Be was partially supported by the Swedish Research Council and the Knut and Alice Wallenberg foundation. M. Butzin was supported by the German Federal Ministry of Education and Research (BMBF) as Research for Sustainable Development (FONA; http://www.fona.de) through the PalMod project (grant number: 01LP1505B). S. Talamo and M. Friedrich are funded by the European Research Council under the European Union’s Horizon 2020 Research and Innovation Programme (grant agreement No. 803147-RESOLUTION, awarded to ST). CA. Turney would like to acknowledge support of the Australian Research Council (FL100100195 and DP170104665). P. Reimer and W. Austin acknowledge the support of the UKRI Natural Environment Research Council (Grant NE/M004619/1). T.J. Heaton is supported by a Leverhulme Trust Fellowship RF-2019-140\9. Other datasets and the IntCal20 database were created without external support through internal funding by the respective laboratories. We also would like to thank various institutions that provided funding or facilities for meetings.

Description: Executive Summary:Observations show that warming of the climate is unequivocal. The global warming observed over the past 50 years is due primarily to human-induced emissions of heat-trapping gases. These emissions come mainly from theburning of fossil fuels (coal, oil, and gas), with important contributions from the clearing of forests, agricultural practices, and other activities.Warming over this century is projected to be considerably greater than over the last century. The global average temperature since 1900 has risen by about 1.5ºF. By 2100, it is projected to rise another 2 to 11.5ºF. The U.S.average temperature has risen by a comparable amount and is very likely to rise more than the global average over this century, with some variation from place to place. Several factors will determine future temperature increases. Increases at the lower end of this range are more likely if global heat-trapping gas emissions are cut substantially. If emissions continue to rise at or near current rates, temperature increases are more likely to be near the upper end of the range. Volcanic eruptions or other natural variations could temporarily counteract some of the human-induced warming, slowing the rise in global temperature, but these effects would only last a few years.Reducing emissions of carbon dioxide would lessen warming over this century and beyond. Sizable early cuts in emissions would significantly reduce the pace and the overall amount of climate change. Earlier cuts in emissions would have a greater effect in reducing climate change than comparable reductions made later. In addition, reducing emissions of some shorter-lived heat-trapping gases, such as methane, and some types of particles, such as soot, would begin to reduce warming within weeks to decades.Climate-related changes have already been observed globally and in the United States. These include increases in air and water temperatures, reduced frost days, increased frequency and intensity of heavy downpours, a rise in sea level, and reduced snow cover, glaciers, permafrost, and seaice. A longer ice-free period on lakes and rivers, lengthening of the growing season, and increased water vapor in the atmosphere have also been observed. Over the past 30 years, temperatures have risen faster in winter than in any other season, with average winter temperatures in the Midwest and northern Great Plains increasing more than 7ºF. Some of the changes have been faster thanprevious assessments had suggested.These climate-related changes are expected to continue while new ones develop. Likely future changes for the United States and surrounding coastal waters include more intense hurricanes with related increases in wind, rain, and storm surges (but not necessarily an increase in the number of these storms that make landfall), as well as drier conditions in the Southwest and Caribbean. Thesechanges will affect human health, water supply, agriculture, coastal areas, and many other aspectsof society and the natural environment.This report synthesizes information from a wide variety of scientific assessments (see page 7) and recently published research to summarize what is known about the observed and projected consequences of climate change on the United States. It combines analysis of impacts on various sectors such as energy, water, and transportation at the national level with an assessment of key impacts on specific regions of the United States. For example, sea-level rise will increase risks of erosion, storm surge damage, and flooding for coastal communities, especially in the Southeast and parts of Alaska. Reduced snowpack and earlier snow melt will alter the timing and amount of water supplies, posingsignificant challenges for water resource managementin the West. (PDF contains 196 pages)

Description: During most of the year, diatom production in the ice-covered Central Arctic Ocean (CAO) is limited by light availability and nutrient supply. Therefore, biological production is thought to be generally low, with higher biological production at the sea ice edge and over partially ice-free shelf areas. The major surface ocean current in the CAO is the Transpolar Drift (TPD), which transports sea ice and water from the rivers and shelves of the Laptev and the East Siberian Seas across the CAO toward the Fram Strait, carrying high amounts of terrestrial-derived material over long distances. We used Si isotopes (δ30Si) to better understand the difference between lower and higher biological production areas and how the TPD potentially affects the Si cycle in the CAO. Our data show low dissolved Si concentrations ([DSi]) paired with high values of δ30Si-DSi in all surface samples indicating fractionation by diatoms. Specifically, outside the TPD influence, all nutrients were depleted and supply was limited due to stratified conditions, thus preventing further phytoplankton growth in the area during the sampling time in late summer- early fall. In contrast, under the TPD influence, diatom primary production was limited by low nitrate and strongly limited by light due to the presence of sea ice, even though [DSi] values were much higher than outside the TPD. Based on δ30Si, we could identify low but measurable DSi utilization in the TPD, potentially highlighting the importance of sea ice-attached diatoms transported to the CAO via the TPD for the Si cycle in this region.