ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    Arctic Sea Ice in CMIP6 (2021)
    Details
    Publication Date: 2021-07-04
    Description: We examine CMIP6 simulations of Arctic sea‐ice area and volume. We find that CMIP6 models produce a wide spread of mean Arctic sea‐ice area, capturing the observational estimate within the multimodel ensemble spread. The CMIP6 multimodel ensemble mean provides a more realistic estimate of the sensitivity of September Arctic sea‐ice area to a given amount of anthropogenic CO2 emissions and to a given amount of global warming, compared with earlier CMIP experiments. Still, most CMIP6 models fail to simulate at the same time a plausible evolution of sea‐ice area and of global mean surface temperature. In the vast majority of the available CMIP6 simulations, the Arctic Ocean becomes practically sea‐ice free (sea‐ice area 〈1 × 106 km2) in September for the first time before the Year 2050 in each of the four emission scenarios SSP1‐1.9, SSP1‐2.6, SSP2‐4.5, and SSP5‐8.5 examined here.
    Description: Plain Language Summary: We examine simulations of Arctic sea ice from the latest generation of global climate models. We find that the observed evolution of Arctic sea‐ice area lies within the spread of model simulations. In particular, the latest generation of models performs better than models from previous generations at simulating the sea‐ice loss for a given amount of CO2 emissions and for a given amount of global warming. In most simulations, the Arctic Ocean becomes practically sea‐ice free (sea‐ice area 〈1 million km2) in September for the first time before the Year 2050.
    Description: Key Points: CMIP6 model simulations of Arctic sea‐ice area capture the observational record in the multimodel ensemble spread. The sensitivity of Arctic sea ice to changes in the forcing is better captured by CMIP6 models than by CMIP5 and CMIP3 models. The majority of available CMIP6 simulations lose most September sea ice for the first time before 2050 in all scenarios.
    Description: National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001
    Description: National Center for Atmospheric Research http://dx.doi.org/10.13039/100005323
    Description: NSF http://dx.doi.org/10.13039/100000001
    Description: CSIRO http://dx.doi.org/10.13039/501100000943
    Description: Earth Systems and Climate Change Hub of the Australian Government's National Environmental Science Program
    Description: European Union's Horizon 2020 Research and Innovation programme
    Description: 727862 APPLICATE
    Description: Joint UK BEIS/Defra Met Office Hadley Centre Climate Programme
    Description: Research Concile of Norway
    Description: Arctic Across Scales Project
    Description: Natural Sciences and Engineering Council of Canada http://dx.doi.org/10.13039/501100000038
    Description: Fond de recherche du Qubec‐Nature et Technologies
    Description: Canadian Meteorological and Oceanographic Society http://dx.doi.org/10.13039/501100002789
    Description: EU Horizon 2020 OSeaIce project
    Description: German Ministry for Education and Research
    Description: H2020 MSCA IF
    Description: Regional and Global Modeling and Analysis program
    Description: NSF‐OPP
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: National Science Foundation http://dx.doi.org/10.13039/100000001
    Description: National Oceanic and Atmospheric Administration http://dx.doi.org/10.13039/100000192
    Description: Canada C150 Chair Program
    Description: NSF‐OPP
    Description: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Description: Canada C150 Chair Program
    Description: Department for Business, Energy and Industrial Strategy (BEIS) http://dx.doi.org/10.13039/100011693
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: EC | H2020 | H2020 Priority Excellent Science | H2020 Marie Skłodowska‐Curie Actions (MSCA) http://dx.doi.org/10.13039/100011102
    Description: F.R.S. ‐ FNRS | Fonds pour la Formation la Recherche dans l'Industrie et dans l'Agriculture (FRIA)
    Description: Knut och Alice Wallenbergs Stiftelse (Knut and Alice Wallenberg Foundation) http://dx.doi.org/10.13039/501100004063
    Description: Max Planck Society http://dx.doi.org/10.13039/501100004189
    Description: National Oceanic and Atmospheric Administration http://dx.doi.org/10.13039/100000192
    Description: Natural Sciences and Engineering Council of Canada http://dx.doi.org/10.13039/501100000038
    Description: NSF http://dx.doi.org/10.13039/100000001
    Description: NSF‐OPP
    Description: Research Council of Norway http://dx.doi.org/10.13039/501100005416
    Description: U.S. Department of Energy (DOE) http://dx.doi.org/10.13039/100000015
    Keywords: 551.41 ; sea ice ; CMIP6 ; Arctic ; climate models ; model evaluation
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    CITATION GEO-LEO
  • 2
    facet.materialart.
    Unknown
    Impact of Sea‐Ice Model Complexity on the Performance of an Unstructured‐Mesh Sea‐Ice/Ocean Model under Different Atmospheric Forcings (2021)
    Details
    Publication Date: 2021-07-21
    Description: We have equipped the unstructured‐mesh global sea‐ice and ocean model FESOM2 with a set of physical parameterizations derived from the single‐column sea‐ice model Icepack. The update has substantially broadened the range of physical processes that can be represented by the model. The new features are directly implemented on the unstructured FESOM2 mesh, and thereby benefit from the flexibility that comes with it in terms of spatial resolution. A subset of the parameter space of three model configurations, with increasing complexity, has been calibrated with an iterative Green's function optimization method to test the impact of the model update on the sea‐ice representation. Furthermore, to explore the sensitivity of the results to different atmospheric forcings, each model configuration was calibrated separately for the NCEP‐CFSR/CFSv2 and ERA5 forcings. The results suggest that a complex model formulation leads to a better agreement between modeled and the observed sea‐ice concentration and snow thickness, while differences are smaller for sea‐ice thickness and drift speed. However, the choice of the atmospheric forcing also impacts the agreement of the FESOM2 simulations and observations, with NCEP‐CFSR/CFSv2 being particularly beneficial for the simulated sea‐ice concentration and ERA5 for sea‐ice drift speed. In this respect, our results indicate that parameter calibration can better compensate for differences among atmospheric forcings in a simpler model (i.e., sea‐ice has no heat capacity) than in more realistic formulations with a prognostic sea‐ice thickness distribution and sea ice enthalpy.
    Description: Plain Language Summary: The role of model complexity in determining the performance of sea‐ice numerical simulations is still not completely understood. Some studies suggest that a more sophisticated description of the sea‐ice physics leads to simulations that agree better with sea‐ice observations. Others, however, fail to establish a link between complex model formulations and improved model performance. Here, we investigate this open question by analyzing a set of sea‐ice simulations performed with a revised and improved sea‐ice model that features substantial modularity in terms of model complexity. Ten model parameters in three different model configurations are optimized to improve the agreement between model results and observations, allowing a fair comparison between model configurations with varying complexity. The model optimization is repeated for two different atmospheric forcings to shed light on the relationship between model complexity and other sources of uncertainty in the sea‐ice simulations, such as those associated with the atmospheric conditions. The results suggest that a more complex formulation of our model can lead to a more appropriate representation of sea ice concentration and snow thickness, while it is less relevant for sea‐ice thickness and drift.
    Description: Key Points: Increased sea‐ice model complexity can improve the simulated sea‐ice concentration and snow thickness Sea‐ice thickness and drift are only weakly affected by model complexity Parameter calibration can better compensate for differences between atmospheric forcings in a simpler model
    Description: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Description: European Commission (EC) http://dx.doi.org/10.13039/501100000780
    Description: US Department of Energy (DOE)
    Keywords: 551.343 ; Arctic ; FESOM2 ; Green's function ; parameter optimization ; sea ice ; unstructured mesh
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    CITATION GEO-LEO
  • 3
    facet.materialart.
    Unknown
    Recent advances in the study of Arctic submarine permafrost (2021)
    Details
    Publication Date: 2021-10-28
    Description: Submarine permafrost is perennially cryotic earth material that lies offshore. Most submarine permafrost is relict terrestrial permafrost beneath the Arctic shelf seas, was inundated after the last glaciation, and has been warming and thawing ever since. As a reservoir and confining layer for gas hydrates, it has the potential to release greenhouse gasses and impact coastal infrastructure, but its distribution and rate of thaw are poorly constrained by observational data. Lengthening summers, reduced sea ice extent and increased solar heating will increase water temperatures and thaw rates. Observations of gas release from the East Siberian shelf and high methane concentrations in the water column and air above it have been attributed to flowpaths created in thawing permafrost. In this context, it is important to understand the distribution and state of submarine permafrost and how they are changing. We assemble recent and historical drilling data on regional submarine permafrost degradation rates and review recent studies that use modelling, geophysical mapping and geomorphology to characterize submarine permafrost. Implications for submarine permafrost thawing are discussed within the context of methane cycling in the Arctic Ocean and global climate change.
    Keywords: 551.38 ; Arctic ; offshore ; submarine permafrost ; subsea ; thaw rates
    Language: English
    Type: map
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    CITATION GEO-LEO
  • 4
    facet.materialart.
    Unknown
    Near-Complete Local Reduction of Arctic Stratospheric Ozone by Severe Chemical Loss in Spring 2020 (2021)
    Details
    Publication Date: 2021-09-27
    Description: In the Antarctic ozone hole, ozone mixing ratios have been decreasing to extremely low values of 0.01–0.1 ppm in nearly all spring seasons since the late 1980s, corresponding to 95–99% local chemical loss. In contrast, Arctic ozone loss has been much more limited and mixing ratios have never before fallen below 0.5 ppm. In Arctic spring 2020, however, ozonesonde measurements in the most depleted parts of the polar vortex show a highly depleted layer, with ozone loss averaged over sondes peaking at 93% at 18 km. Typical minimum mixing ratios of 0.2 ppm were observed, with individual profiles showing values as low as 0.13 ppm (96% loss). The reason for the unprecedented chemical loss was an unusually strong, long-lasting, and cold polar vortex, showing that for individual winters the effect of the slow decline of ozone-depleting substances on ozone depletion may be counteracted by low temperatures.
    Keywords: 551.9 ; ozone ; stratosphere ; ozone loss ; Arctic ; ozone hole ; temperature
    Language: English
    Type: map
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    CITATION GEO-LEO
  • 5
    facet.materialart.
    Unknown
    Modeling the Microwave Emission of Snow on Arctic Sea Ice for Estimating the Uncertainty of Satellite Retrievals (2021)
    Details
    Publication Date: 2021-10-15
    Description: Within a rapidly changing Arctic climate system, snow on sea ice is an important climate parameter. A common method to derive snow depth on an Arctic-wide scale is based on passive microwave satellite observations. However, the uncertainties of this method are not well constrained. In this study, we estimate the influence of geophysical parameters, including ice, snow, and atmospheric properties on passive microwave snow depth retrievals using a Monte Carlo uncertainty estimation. The results are based on model simulations from the Microwave Emission Model for Layered Snowpacks, the SNOWPACK model, and from the Passive and Active Microwave TRAnsfer model. All simulations are based on in situ observations obtained during the N-ICE2015 campaign. The average uncertainty in potential snow depth retrievals is between 11% and 19%, depending on the microwave frequencies used and increases with increasing snow depth. For lower-frequency retrievals (including 6.9 GHz), unknown snow properties are the strongest source of uncertainty while for higher-frequency retrievals (including 36.5 GHz), the contribution of ice, snow properties, and clouds is equally strong.
    Keywords: 551.5 ; snow ; remote sensing ; modeling ; Arctic
    Language: English
    Type: map
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    CITATION GEO-LEO
  • 6
    facet.materialart.
    Unknown
    Following moist intrusions into the Arctic using SHEBA observations in a Lagrangian perspective (2021)
    Details
    Publication Date: 2021-09-24
    Description: Warm and moist air masses are transported into the Arctic from lower latitudes throughout the year. Especially in winter, such moist intrusions (MIs) can trigger cloud formation and surface warming. While a typical cloudy state of the Arctic winter boundary layer has been linked to the advection of moist air masses, direct observations of the transformation from moist midlatitude to dry Arctic air are lacking. Here, we have used observations from the Surface Heat Budget of the Arctic Ocean (SHEBA) project to compile Eulerian observations along the trajectories of warm and cold air masses in a Lagrangian sense, showing the cooling and drying of air masses over sea ice and moistening over the open ocean. Air masses originating mostly over open water generate cloudy conditions over the observation site, whereas air masses originating over continents or sea ice generate radiatively clear conditions. We recommend using our case-studies and the method of linking expeditions to station soundings via back-trajectories for modelling work in future campaigns.
    Keywords: 551.5 ; air mass transformation ; Arctic ; cloudy state ; moist air intrusion ; polar atmosphere ; SHEBA
    Language: English
    Type: map
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    CITATION GEO-LEO
  • 7
    facet.materialart.
    Unknown
    Sea Ice and Atmospheric Parameter Retrieval From Satellite Microwave Radiometers: Synergy of AMSR2 and SMOS Compared With the CIMR Candidate Mission (2021)
    Details
    Publication Date: 2021-10-06
    Description: Research on improving the prediction skill of climate models requires refining the quality of observational data used for initializing and tuning the models. This is especially true in the polar regions where uncertainties about the interactions between sea ice, ocean, and atmosphere are driving ongoing monitoring efforts. The Copernicus Imaging Microwave Radiometer (CIMR) is an European Space Agency (ESA) candidate mission which promises to offer high resolution, low uncertainty observation capabilities at the 1.4, 6.9, 10.65, 18.7, and 36.5 GHz frequencies. To assess the potential impact of CIMR for sea ice parameter retrieval, a comparison is made between retrievals based on present AMSR2 observations and a retrieval using future CIMR equivalent observations over a data set of validated sea ice concentration (SIC) values. An optimal estimation retrieval method (OEM) is used which can use input from different channel combinations to retrieve seven geophysical parameters (sea ice concentration, multi-year ice fraction, ice surface temperature, columnar water vapor, liquid water path, over ocean wind speed, and sea surface temperature). An advantage of CIMR over existing radiometers is that it would provide higher spatial resolution observations at the lower frequency channels (6.9, 10.65, and 18.7 GHz) which are less sensitive to atmospheric influence. This enables the passive microwave based retrieval of SIC and other surface parameters with higher resolution and lower uncertainty than is currently possible. An information content analysis expands the comparison between AMSR2 and CIMR to all retrievable surface and atmospheric parameters. This analysis quantifies the contributions to the observed signal and highlights the differences between different input channel combinations. The higher resolution of the low frequency CIMR channels allow for unprecedented detail to be achieved in Arctic passive microwave sea ice retrievals. The presence of 1.4 GHz channels on board CIMR opens up the possibility for thin sea ice thickness (SIT) retrieval. A combination of collocated AMSR2 and SMOS observations is used to simulate a full CIMR suite of measurements, and the OEM is modified to include SIT as a retrieval parameter. The output from different retrieval configurations is compared with an operational SIT product. The CIMR instrument can provide increased accuracy for SIC retrieval at very high resolutions with a combination of the 18.7 and 36.5 GHz channels while also maintaining sensitivity for atmospheric water vapor retrieval. In combination with the 1.4 GHz channels, SIT can be added as an eighth retrieval parameter with performance on par with existing operational products.
    Keywords: 551.6 ; sea ice ; satellite semote sensing ; passive microwave ; Arctic ; optimal estimation ; information content analysis
    Language: English
    Type: map
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    CITATION GEO-LEO
  • 8
    facet.materialart.
    Unknown
    Arctic Ocean Surface Energy Flux and the Cold Halocline in Future Climate Projections (2021)
    Details
    Publication Date: 2021-10-25
    Description: Ocean heat transport is often thought to play a secondary role for Arctic surface warming in part because warm water which flows northward is prevented from reaching the surface by a cold and stable halocline layer. However, recent observations in various regions indicate that occasionally, warm water is found directly below the surface mixed layer. Here we investigate Arctic Ocean surface energy fluxes and the cold halocline layer in climate model simulations from the Coupled Model Intercomparison Project Phase 5. An ensemble of 15 models shows decreased sea ice formation and increased ocean energy release during fall, winter, and spring for a high-emission future scenario. Along the main pathways for warm water advection, this increased energy release is not locally balanced by increased Arctic Ocean energy uptake in summer. Because during Arctic winter, the ocean mixed layer is mainly heated from below, we analyze changes of the cold halocline layer in the monthly mean Coupled Model Intercomparison Project Phase 5 data. Fresh water acts to stabilize the upper ocean as expected based on previous studies. We find that in spite of this stabilizing effect, periods in which warm water is found directly or almost directly below the mixed layer and which occur mainly in winter and spring become more frequent in high-emission future scenario simulations, especially along the main pathways for warm water advection. This could reduce sea ice formation and surface albedo.
    Keywords: 551.46 ; 551.6 ; Arctic ; climate change ; cold halocline ; climate modeling
    Language: English
    Type: map
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    CITATION GEO-LEO
  • 9
    facet.materialart.
    Unknown
    In situ sounding of radiative flux profiles through the Arctic lower troposphere (2020)
    Springer International Publishing
    Details
    Publication Date: 2023-06-05
    Description: In situ profiles and fixed-altitude time series of all four components of net radiation were obtained at Ny-Ålesund, Svalbard (78.9° N, 11.9° E), in the period May 04–21, 2015. Measurements were performed using adapted high-quality instrumentation classified as “secondary standard” carried by a tethered balloon system. Balloon-lifted measurements of albedo under clear-sky conditions demonstrate the local dependence on altitude and on the surface inhomogeneity of this parameter over coastal terrain of Ny-Ålesund. Depending on the surface composition within the sensor’s footprint near the coastline, the albedo over predominantly snow-covered surfaces was found to decrease to 0.548 and 0.452 at 494 m and 881 m altitude compared with 0.731 and 0.788 measured with near-surface references, respectively. Albedo profiles show an all-sky maximum at 150 m above surface level due to local surface inhomogeneity, and an averaged vertical change rate of − 0.040/100 up to 750 m aboveground level (clear sky) and − 0.034/100 m (overcast). Profiling of arctic low-level clouds reveals distinct vertical gradients in all radiative fluxes but longwave upward at the cloud top. Observed radiative cooling at the top of a partly dissolving stratus cloud with heating rates of − 40.4 to − 62.1 Kd−1 in subsequent observations is exemplified.
    Description: Bundesrepublik Deutschland, Deutscher Wetterdienst, vertreten durch den Vorstand, Deutsche Meteorologische Bibliothek (4242)
    Keywords: ddc:551.5 ; Atmosphere ; Arctic ; In-situ profiling ; Albedo ; Clouds ; Heating rates
    Language: English
    Type: doc-type:article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    CITATION GEO-LEO
  • 10
    facet.materialart.
    Unknown
    Quantifying Ice‐Sheet Derived Lead (Pb) Fluxes to the Ocean; A Case Study at Nioghalvfjerdsbræ (2022)
    Details
    Publication Date: 2023-11-17
    Description: Concentrations of the toxic element lead (Pb) are elevated in seawater due to historical emissions. While anthropogenic atmospheric emissions are the dominant source of dissolved Pb (dPb) to the Atlantic Ocean, evidence is emerging of a natural source associated with subglacial discharge into the ocean but this has yet to be constrained around Greenland. Here, we show subglacial discharge from the cavity underneath Nioghalvfjerdsbræ floating ice tongue, is a previously unrecognized source of dPb to the NE Greenland Shelf. Contrasting cavity‐inflowing and cavity‐outflowing waters, we constrain the associated net‐dPb flux as 2.2 ± 1.4 Mg·yr−1, of which ∼90% originates from dissolution of glacial bedrock and cavity sediments. We propose that the retreat of the floating ice tongue, the ongoing retreat of many glaciers on Greenland, associated shifts in sediment dynamics, and enhanced meltwater discharges into shelf waters may result in pronounced changes, possibly increases, in net‐dPb fluxes to coastal waters.
    Description: Plain Language Summary: Lead (Pb) is a toxic element. Hundreds of thousands of tons have historically been emitted into the atmosphere through use of leaded gasoline, ore‐smelting and coal‐combustion which led to large‐scale deposition of Pb into the ocean and onto the Greenland Ice Sheet. Since the phase‐out of leaded gasoline, concentrations of dissolved Pb in the surface ocean have declined, increasing the relative importance of other, natural sources of Pb to the marine environment. In 2016, we conducted a survey near Nioghalvfjerdsbræ, one of Greenland’s largest marine‐terminating glaciers, to investigate if Greenland Ice Sheet discharge is a source of Pb to the Northeast Greenland Shelf. We observed elevated dissolved Pb concentrations at intermediate depths within a ⁓60 km radius downstream of the Nioghalvfjerdsbræ terminus. The Pb enrichment originates from underneath the glacier’s floating ice tongue. Lead sources underneath Nioghalvfjerdsbræ likely include Pb from eroded bedrock and exchange with fjord sediments. Our calculations suggest that Nioghalvfjerdsbræ dissolved Pb discharge is comparable to that from small Arctic rivers. Given the widespread occurance of Pb‐rich minerals across Greenland, observed increases in meltwater discharge and the retreat of marine‐terminating glaciers could increase dPb supply to Greenlandic shelf regions.
    Description: Key Points: Helium and neon show strong evidence for a subglacial source of Pb discharging onto the NE Greenland Shelf. Contrasting inflowing and outflowing waters beneath the floating ice tongue of Nioghalvfjerdsbræ shows a 2‐3‐fold dPb enrichment. The dissolved Pb flux from Nioghalvfjerdsbræ (2.2 ± 1.4 Mg·yr−1) is comparable to small Arctic rivers, with ∼90% of a sedimentary origin.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Kuwait Institute for Scientific Research http://dx.doi.org/10.13039/501100005074
    Description: Swiss Polar Foundation
    Description: https://doi.pangaea.de/10.1594/PANGAEA.871028
    Description: https://doi.pangaea.de/10.1594/PANGAEA.871030
    Description: https://doi.pangaea.de/10.1594/PANGAEA.879197
    Description: https://doi.pangaea.de/10.1594/PANGAEA.905347
    Description: https://doi.pangaea.de/10.1594/PANGAEA.933431
    Description: https://doi.pangaea.de/10.1594/PANGAEA.931336
    Description: https://doi.org/10.5194/essd-8-543-2016
    Keywords: ddc:551 ; Greenland ice sheet ; Arctic ; marine‐terminating glacier ; Nioghalvfjerdsbrae ; lead fluxes ; GEOTRACES
    Language: English
    Type: doc-type:article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    CITATION GEO-LEO
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...