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Author Thomas Frederikse, Surendra Adhikari, Tim J. Daley, Sönke Dangendorf, Roland Gehrels, Felix Landerer, Marta Marcos, Thomas L. Newton, Graham Rush, Aimée B. A. Slangen, Guy Wöppelmann doi  openurl
  Title Constraining 20th-Century Sea-Level Rise in the South Atlantic Ocean Type Journal
  Year 2021 Publication Journal of Geophysical Research: Oceans Abbreviated Journal  
  Volume 126 Issue 3 Pages e2020JC016970  
  Keywords data rescue salt-marsh proxies sea-level changes South Atlantic tide gauges  
  Abstract Sea level in the South Atlantic Ocean has only been measured at a small number of tide-gauge locations, which causes considerable uncertainty in 20th-century sea-level trend estimates in this basin. To obtain a better-constrained sea-level trend in the South Atlantic Ocean, this study aims to answer two questions. The first question is: can we combine new observations, vertical land motion estimates, and information on spatial sampling biases to obtain a likely range of 20th-century sea-level rise in the South Atlantic? We combine existing observations with recovered observations from Dakar and a high-resolution sea-level reconstruction based on salt-marsh sediments from the Falkland Islands and find that the rate of sea-level rise in the South Atlantic has likely been between 1.1 and 2.2 mm year−1 (5%–95% confidence intervals), with a central estimate of 1.6 mm year−1. This rate is on the high side, but not statistically different compared to global-mean trends from recent reconstructions. The second question is: are there any physical processes that could explain a large deviation from the global-mean sea-level trend in the South Atlantic? Sterodynamic (changes in ocean dynamics and steric effects) and gravitation, rotation, and deformation effects related to ice mass loss and land water storage have probably led to a 20th-century sea-level trend in the South Atlantic above the global mean. Both observations and physical processes thus suggest that 20th-century sea-level rise in the South Atlantic has been about 0.3 mm year−1 above the rate of global-mean sea-level rise, although even with the additional observations, the uncertainties are still too large to distinguish a statistically significant difference.  
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  Series Volume Series Issue Edition  
  ISSN 2169-9291 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8603  
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Author R. Sulzbach, H. Dobslaw, M. Thomas doi  openurl
  Title High-Resolution Numerical Modeling of Barotropic Global Ocean Tides for Satellite Gravimetry Type Journal
  Year 2021 Publication Journal of Geophysical Research: Oceans Abbreviated Journal  
  Volume 126 Issue 5 Pages e2020JC017097  
  Keywords M2-tide minor tides pole-rotation self-attraction and loading tide-generating potential topographic wavedrag  
  Abstract The recently upgraded barotropic tidal model TiME is employed to study the influence of fundamental tidal processes, the chosen model resolution, and the bathymetric map on the achievable model accuracy, exemplary for the M2 tide. Additionally, the newly introduced pole-rotation scheme allows to estimate the model’s inherent precision (open ocean rms: 0.90 cm) and enables studies of the Arctic domain without numerical deviations originating from pole cap handling. We find that the smallest open ocean rms with respect to the FES14-atlas (3.39 cm) is obtained when tidal dissipation is carried out to similar parts by quadratic bottom friction, wave drag, and parametrized eddy-viscosity. This setting proves versatile to obtaining high accuracy values for a diverse ensemble of additional partial tides. Using the preferred model settings, we show that for certain minor tides it is possible to obtain solutions that are more accurate than results derived with admittance assumptions from data-constrained tidal atlases. As linear admittance derived minor tides are routinely used for de-aliasing of satellite gravimetric data, this opens the potential for improving gravity field products by employing the solutions from TiME.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2169-9291 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8605  
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Author Richard D. Ray, Bryant D. Loomis, Victor Zlotnicki doi  openurl
  Title The mean seasonal cycle in relative sea level from satellite altimetry and gravimetry Type Journal
  Year 2021 Publication Journal of Geodesy Abbreviated Journal  
  Volume 95 Issue 7 Pages 80  
  Keywords Annual geocenter motion Annual land motion Annual/semiannual cycle Satellite altimetry  
  Abstract Satellite altimetry and gravimetry are used to determine the mean seasonal cycle in relative sea level, a quantity relevant to coastal flooding and related applications. The main harmonics (annual, semiannual, terannual) are estimated from 25 years of gridded altimetry, while several conventional altimeter “corrections” (gravitational tide, pole tide, and inverted barometer) are restored. To transform from absolute to relative sea levels, a model of vertical land motion is developed from a high-resolution seasonal mass inversion estimated from satellite gravimetry. An adjustment for annual geocenter motion accounts for use of a center-of-mass reference frame in satellite orbit determination. A set of 544 test tide gauges, from which seasonal harmonics have been estimated from hourly measurements, is used to assess how accurately each adjustment to the altimeter data helps converge the results to true relative sea levels. At these gauges, the median annual and semiannual amplitudes are 7.1 cm and 2.2 cm, respectively. The root-mean-square differences with altimetry are 3.24 and 1.17 cm, respectively, which are reduced to 1.93 and 0.86 cm after restoration of corrections and adjustment for land motion. Example outliers highlight some limitations of present-day coastal altimetry owing to inadequate spatial resolution: upwelling and currents off Oregon and wave setup at Minamitori Island.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1432-1394 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8610  
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Author Andreas Richter, Alexey A. Ekaykin, Matthias O. Willen, Vladimir Ya. Lipenkov, Andreas Groh, Sergey V. Popov, Mirko Scheinert, Martin Horwath, Reinhard Dietrich doi  openurl
  Title Surface Mass Balance Models Vs. Stake Observations: A Comparison in the Lake Vostok Region, Central East Antarctica Type Journal
  Year 2021 Publication Frontiers in Earth Science Abbreviated Journal  
  Volume 9 Issue Pages 388  
  Keywords  
  Abstract The surface mass balance (SMB) is very low over the vast East Antarctic Plateau, for example in the Vostok region, where the mean SMB is on the order of 20–35 kg m-2 a-1. The observation and modeling of spatio-temporal SMB variations are equally challenging in this environment. Stake measurements carried out in the Vostok region provide SMB observations over half a century (1970–2019). This unique data set is compared with SMB estimations of the regional climate models RACMO2.3p2 (RACMO) and MAR3.11 (MAR). We focus on the SMB variations over time scales from months to decades. The comparison requires a rigorous assessment of the uncertainty in the stake observations and the spatial scale dependence of the temporal SMB variations. Our results show that RACMO estimates of annual and multi-year SMB agree well with the observations. The regression slope between modelled and observed temporal variations is close to 1.0 for this model. SMB simulations by MAR are affected by a positive bias which amounts to 6 kg m-2 a-1 at Vostok station and 2 kg m-2 a-1 along two stake profiles between Lake Vostok and Ridge B. None of the models is capable to reproduce the seasonal distributions of SMB and precipitation. Model SMB estimates are used in assessing the ice-mass balance and sea-level contribution of the Antarctic Ice Sheet by the input-output method. Our results provide insights into the uncertainty contribution of the SMB models to such assessments.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2296-6463 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8030  
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Author Jonathan D. Wille, Vincent Favier, Irina V. Gorodetskaya, Cécile Agosta, Christoph Kittel, Jai Chowdhry Beeman, Nicolas C. Jourdain, Jan T. M. Lenaerts, Francis Codron doi  openurl
  Title Antarctic Atmospheric River Climatology and Precipitation Impacts Type Journal
  Year 2021 Publication Journal of Geophysical Research: Atmospheres Abbreviated Journal  
  Volume 126 Issue 8 Pages e2020JD033788  
  Keywords Antarctica atmospheric rivers climatology meteorology  
  Abstract The Antarctic ice sheet (AIS) is sensitive to short-term extreme meteorological events that can leave long-term impacts on the continent's surface mass balance (SMB). We investigate the impacts of atmospheric rivers (ARs) on the AIS precipitation budget using an AR detection algorithm and a regional climate model (Modèle Atmosphérique Régional) from 1980 to 2018. While ARs and their associated extreme vapor transport are relatively rare events over Antarctic coastal regions (∼3 days per year), they have a significant impact on the precipitation climatology. ARs are responsible for at least 10% of total accumulated snowfall across East Antarctica (localized areas reaching 20%) and a majority of extreme precipitation events. Trends in AR annual frequency since 1980 are observed across parts of AIS, most notably an increasing trend in Dronning Maud Land; however, interannual variability in AR frequency is much larger. This AR behavior appears to drive a significant portion of annual snowfall trends across East Antarctica, while controlling the interannual variability of precipitation across most of the AIS. AR landfalls are most likely when the circumpolar jet is highly amplified during blocking conditions in the Southern Ocean. There is a fingerprint of the Southern Annular Mode (SAM) on AR variability in West Antarctica with SAM+ (SAM−) favoring increased AR frequency in the Antarctic Peninsula (Amundsen-Ross Sea coastline). Given the relatively large influence ARs have on precipitation across the continent, it is advantageous for future studies of moisture transport to Antarctica to consider an AR framework especially when considering future SMB changes.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2169-8996 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8327  
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Author Charles Amory, Christoph Kittel, Louis Le Toumelin, Cécile Agosta, Alison Delhasse, Vincent Favier, Xavier Fettweis doi  openurl
  Title Performance of MAR (v3.11) in simulating the drifting-snow climate and surface mass balance of Adélie Land, East Antarctica Type Journal
  Year 2021 Publication Geoscientific Model Development Abbreviated Journal  
  Volume 14 Issue 6 Pages 3487-3510  
  Keywords  
  Abstract

Abstract. Drifting snow, or the wind-driven transport of snow particles originating from clouds and the surface below and above 2 m above ground and their concurrent sublimation, is a poorly documented process on the Antarctic ice sheet, which is inherently lacking in most climate models. Since drifting snow mostly results from erosion of surface particles, a comprehensive evaluation of this process in climate models requires a concurrent assessment of simulated drifting-snow transport and the surface mass balance (SMB). In this paper a new version of the drifting-snow scheme currently embedded in the regional climate model MAR (v3.11) is extensively described. Several important modifications relative to previous version have been implemented and include notably a parameterization for drifting-snow compaction of the uppermost snowpack layer, differentiated snow density at deposition between precipitation and drifting snow, and a rewrite of the threshold friction velocity above which snow erosion initiates. Model results at high resolution (10 km) over Adélie Land, East Antarctica, for the period 2004–2018 are presented and evaluated against available near-surface meteorological observations at half-hourly resolution and annual SMB estimates. The evaluation demonstrates that MAR resolves the local drifting-snow frequency and transport up to the scale of the drifting-snow event and captures the resulting observed climate and SMB variability, suggesting that this model version can be used for continent-wide applications.

 
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  ISSN 1991-959X ISBN Medium  
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  Notes Approved yes  
  Call Number Serial 8428  
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Author Benjamin Pohl, Vincent Favier, Jonathan Wille, Danielle G Udy, Tessa R Vance, Julien Pergaud, Niels Dutrievoz, Juliette Blanchet, Christoph Kittel, Charles Amory, Gerhard Krinner, Francis Codron doi  openurl
  Title Relationship Between Weather Regimes and Atmospheric Rivers in East Antarctica Type Journal
  Year 2021 Publication Journal of Geophysical Research: Atmospheres Abbreviated Journal  
  Volume 126 Issue 24 Pages e2021JD035294  
  Keywords atmospheric rivers East Antarctica snowfall amounts temperature anomalies weather regimes  
  Abstract Here, we define weather regimes in the East Antarctica—Southern Ocean sector based on daily anomalies of 700 hPa geopotential height derived from ERA5 reanalysis during 1979–2018. Most regimes and their preferred transitions depict synoptic-scale disturbances propagating eastwards off the Antarctic coastline. While regime sequences are generally short, their interannual variability is strongly driven by the polarity of the Southern Annular Mode (SAM). Regime occurrences are then intersected with atmospheric rivers (ARs) detected over the same region and period. ARs are equiprobable throughout the year, but clearly concentrate during regimes associated with a strong atmospheric ridges/blockings on the eastern part of the domain, which act to channel meridional advection of heat and moisture from the lower latitudes towards Antarctica. Both regimes and ARs significantly shape climate variability in Antarctica. Regimes favorable to AR occurrences are associated with anomalously warm and humid conditions in coastal Antarctica and, to a lesser extent, the hinterland parts of the Antarctic plateau. These anomalies are strongly enhanced during AR events, with warmer anomalies and dramatically amplified snowfall amounts. Large-scale conditions favoring AR development are finally explored. They show weak dependency to the SAM, but particularly strong atmospheric ridges/blockings over the Southern Ocean appear as the most favorable pattern, in which ARs can be embedded, and to which they contribute.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2169-8996 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8430  
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Author F. Bultelle, I. Boutet, S. Devin, F. Caza, Y. St-Pierre, R. Péden, P. Brousseau, P. Chan, D. Vaudry, F. Le Foll, M. Fournier, M. Auffret, B. Rocher doi  openurl
  Title Molecular response of a sub-antarctic population of the blue mussel (Mytilus edulis platensis) to a moderate thermal stress Type Journal
  Year 2021 Publication Marine Environmental Research Abbreviated Journal  
  Volume 169 Issue Pages 105393  
  Keywords 2DE Abiotic stress Biomonitoring Gills Indicator species Kerguelen island Mytilus sp. qRT-PCR Temperature  
  Abstract The Kerguelen Islands (49°26′S, 69°50′E) represent a unique environment due to their geographical isolation, which protects them from anthropogenic pollution. The ability of the endemic mussel, part of the Mytilus complex, to cope with moderate heat stress was explored using omic tools. Transcripts involved in six major metabolic functions were selected and the qRT-PCR data indicated mainly changes in aerobic and anaerobic energy metabolism and stress response. Proteomic comparisons revealed a typical stress response pattern with cytoskeleton modifications and elements suggesting increased energy metabolism. Results also suggest conservation of protein homeostasis by the long-lasting presence of HSP while a general decrease in transcription is observed. The overall findings are consistent with an adaptive response to moderate stresses in mussels in good physiological condition, i.e. living in a low-impact site, and with the literature concerning this model species. Therefore, local blue mussels could be advantageously integrated into biomonitoring strategies, especially in the context of Global Change.  
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  Series Volume Series Issue Edition  
  ISSN 0141-1136 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8256  
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Author G. J. Sutton, C. A. Bost, A. Z. Kouzani, S. D. Adams, K. Mitchell, J. P. Y. Arnould doi  openurl
  Title Fine-scale foraging effort and efficiency of Macaroni penguins is influenced by prey type, patch density and temporal dynamics Type Journal
  Year 2021 Publication Marine Biology Abbreviated Journal  
  Volume 168 Issue 1 Pages 3  
  Keywords  
  Abstract Difficulties quantifying in situ prey patch quality have limited our understanding of how marine predators respond to variation within and between patches, and throughout their foraging range. In the present study, animal-borne video, GPS, accelerometer and dive behaviour data loggers were used to investigate the fine-scale foraging behaviour of Macaroni penguins (Eudyptes chrysolophus) in response to prey type, patch density and temporal variation in diving behaviour. Individuals mainly dived during the day and utilised two strategies, targeting different prey types. Subantarctic krill (Euphausia vallentini) were consumed during deep dives, while small soft-bodied fish were captured on shallow dives or during the ascent phase of deep dives. Despite breeding in large colonies individuals seemed to be solitary foragers and did not engage with conspecifics in coordinated behaviour as seen in other group foraging penguin species. This potentially reflects the high abundance and low manoeuvrability of krill. Video data were used to validate prey capture signals in accelerometer data and a Support Vector Machine learning algorithm was developed to identify prey captures that occurred throughout the entire foraging trip. Prey capture rates indicated that Macaroni penguins continued to forage beyond the optimal give up time. However, bout-scale analysis revealed individuals terminated diving behaviour for reasons other than patch quality. These findings indicate that individuals make complex foraging decisions in relation to their proximate environment over multiple spatio-temporal scales.  
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  Series Volume Series Issue Edition  
  ISSN 1432-1793 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 2037  
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Author Tomoko Narazaki, Itsumi Nakamura, Kagari Aoki, Takashi Iwata, Kozue Shiomi, Paolo Luschi, Hiroyuki Suganuma, Carl G. Meyer, Rui Matsumoto, Charles A. Bost, Yves Handrich, Masao Amano, Ryosuke Okamoto, Kyoichi Mori, Stéphane Ciccione, Jérôme Bourjea, Katsufumi Sato doi  openurl
  Title Similar circling movements observed across marine megafauna taxa Type Journal
  Year 2021 Publication iScience Abbreviated Journal  
  Volume 24 Issue 4 Pages 102221  
  Keywords Animals Biological Sciences Ecology Ethology Zoology  
  Abstract Advances in biologging technology have enabled 3D dead-reckoning reconstruction of marine animal movements at spatiotemporal scales of meters and seconds. Examining high-resolution 3D movements of sharks (Galeocerdo cuvier, N = 4; Rhincodon typus, N = 1), sea turtles (Chelonia mydas, N = 3), penguins (Aptenodytes patagonicus, N = 6), and marine mammals (Arctocephalus gazella, N = 4; Ziphius cavirostris, N = 1), we report the discovery of circling events where animals consecutively circled more than twice at relatively constant angular speeds. Similar circling behaviors were observed across a wide variety of marine megafauna, suggesting these behaviors might serve several similar purposes across taxa including foraging, social interactions, and navigation.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2589-0042 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8095  
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