Margesin R., Feller G., Gerday C. & Russell N. (2002). Cold-adapted microorganism: adaptation strategies and biotechnological potential. The encyclopedia of environmental microbiology, 2, 871–885.
Abstract: in Bitton G. (ed.), The Encyclopedia of Environmental Microbiology, vol. 2
Programme: 193
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Kai Bischof, Peter Convey, Pedro Duarte, Jean-Pierre Gattuso, Maria Granberg, Haakon Hop, Clara Hoppe, Carlos Jiménez, Leonid Lisitsyn, Brezo Martinez, Michael Y. Roleda, Peter Thor, Józef M. Wiktor, Geir Wing Gabrielsen. (2019). Kongsfjorden as Harbinger of the Future Arctic: Knowns, Unknowns and Research Priorities.
Abstract: Due to its year-round accessibility and excellent on-site infrastructure, Kongsfjorden and the Ny-Ålesund Research and Monitoring Facility have become established as a primary location to study the impact of environmental change on Arctic coastal ecosystems. Due to its location right at the interface of Arctic and Atlantic oceanic regimes, Kongsfjorden already experiences large amplitudes of variability in physico/chemical conditions and might, thus, be considered as an early warning indicator of future changes, which can then be extrapolated in a pan-Arctic perspective. Already now, Kongsfjorden represents one of the best-studied Arctic fjord systems. However, research conducted to date has concentrated largely on small disciplinary projects, prompting the need for a higher level of integration of future research activities. This contribution, thus, aims at identifying gaps in knowledge and research priorities with respect to ecological and adaptive responses to Arctic ecosystem changes. By doing so we aim to provide a stimulus for the initiation of new international and interdisciplinary research initiatives.
Keywords: Flagship program Indicator species Land-sea-ocean-interaction Monitoring Pan-Arctic
Programme: 1141
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Dominic Saunderson, Andrew Mackintosh, Felicity McCormack, Richard Selwyn Jones, Ghislain Picard. (2022). Surface melt on the Shackleton Ice Shelf, East Antarctica (2003–2021).
Abstract: Many ice shelves in Antarctica experience surface melt each summer, with potentially severe consequences for sea level rise. However, large interannual and regional variability in surface melt increases uncertainty in predictions of how ice shelves will react to climate change. Previous studies of surface melt have usually focused on either a process-level understanding of surface melt through energy balance investigations, or used regional melt metrics to quantify interannual variability in satellite observations of surface melt. Here, we use an approach that helps bridge the gap between work at these two scales. Using daily passive microwave observations from the AMSR-E and AMSR-2 sensors, and the machine learning approach of a self-organising map, we identify nine representative spatial distributions (“patterns”) of surface melt on the Shackleton Ice Shelf, East Antarctica, over the previous two decades (2002/03–2020/21). Our results point to a significant role for surface air temperatures in controlling the interannual variability of summer melt, and also reveal the influence of local controls on driving melt. In particular, prolonged melt in the south-east of the shelf and along the grounding line shows the importance of katabatic winds and surface albedo. Our approach highlights the necessity of understanding both local and large-scale controls on surface melt, and demonstrates that self-organising maps can be used to investigate the variability of surface melt on Antarctic ice shelves.
Programme: 1110
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Ghislain Picard, Marion Leduc-Leballeur, Alison F. Banwell, Ludovic Brucker, Giovanni Macelloni. (2022). The sensitivity of satellite microwave observations to liquid water in the Antarctic snowpack.
Abstract: Surface melting on the Antarctic Ice Sheet has been monitored by satellite microwave radiometery for over 40 years. Despite this long perspective, our understanding of the microwave emission from wet snow is still limited, preventing the full exploitation of these observations to study supraglacial hydrology. Using the Snow Microwave Radiative Transfer (SMRT) model, this study investigates the sensitivity of microwave brightness temperature to snow liquid water content at frequencies from 1.4 to 37 GHz. We first determine the snowpack properties for 8 selected coastal sites by retrieving profiles of density, grain size and ice layers from microwave observations when the snowpack is dry during winter time. Second, a series of brightness temperature simulations is run with added water. The results show that: i) a small amount of liquid water (≈0.5 kg m-2 can be detected, but the actual amount can not be retrieved in the full range of possible water contents, ii) the detection of a buried wet layer is possible up to a maximum 1 to 6 m depth depending on the frequency (6–37 GHz) and on the site, iii) surface ponds and water-saturated areas may prevent melt detection, but the current coverage of these water bodies in the large satellite field of view is presently too small in Antarctica to have noticeable effects, iv) at 1.4 GHz, while the simulations are less reliable, we found a weaker sensitivity to liquid water and the maximal depth of detection is relatively shallow (<10 m) compared to the typical radiation penetration depth in dry firn (≈1000 m) at this low frequency. These numerical results pave the way for the development of improved multi-frequency algorithms to detect melt intensity and depth in the Antarctic snowpack.
Programme: 1110
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Magand, O.; Picard, G.; Brucker, L.; Fily, M.; Genthon, C. (2008). Snow melting bias in microwave mapping of Antarctic snow accumulation. TCD, 2(2), 255–273.
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E. Le Meur, M. Sacchettini, S. Garambois, E. Berthier, A. S. Drouet, G. Durand, D. Young, J. S. Greenbaum, D. D. Blankenship, J. W. Holt, E. Rignot, J. Mouginot, Y. Gim, D. Kirchner, B. de Fleurian, O. Gagliardini and F. Gillet-Chaulet
. (2013). Two independent methods for mapping the grounding line of an outlet glacier – example from the Astrolabe Glacier, Terre Adélie, Antarctica
. The Cryosphere Discuss., 7(4), 3969–4014.
Abstract: Abstract
The grounding line is a key element acting on the dynamics of coastal outlet glaciers.
Knowing its position accurately is fundamental for both modelling the glacier dynamics
and establishing a benchmark to which one can later refer in case of change. Here we
� �map the grounding line of the Astrolabe Glacier in East Antarctica (66 41 S; 140 05 E),
using hydrostatic and tidal methods. The first method is based on new surface and
ice thickness data from which the line of buoyant flotation is found. We compare this
hydrostatic map with kinematic GPS measurements of the tidal response of the ice
surface. By detecting the transitions where the ice starts to move vertically in response
to the tidal forcing we find control points for the grounding line position along GPS
profiles. With the help of a 2-dimensional elastic plate model, rigid elastic deviations are
computed and applied to these control points. Once the extent of the grounding zone,
the kinematic approach is consistent with the hydrostatic map. These two approaches
lead us to propose a grounding line for the Astrolabe Glacier that significantly deviates
from those obtained so far from satellite imagery.
Programme: 1053
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Picard G, Royer A, Arnaud L, Fily M, . (2013). Influence of meter-scale wind-formed features on the variability of the microwave brightness temperature around Dome C in Antarctica
. The Cryosphere Discuss., 7(4), 3675–3716.
Abstract: Space-borne passive microwave radiometers are widely used to retrieve information in snowy regions by exploiting the high sensitivity of microwave emission to snow properties. For the Antarctic Plateau, many studies presenting retrieval algorithms or numerical simulations have assumed, explicitly or not, that the subpixel-scale heterogeneity is negligible and that the retrieved properties were representative of whole pixels. In this paper, we investigate the spatial variations of brightness temperature over a range of a few kilometers in the Dome C area. Using ground-based radiometers towed by a vehicle allowing measurements with meter resolution, we collected brightness temperature transects at 11, 19 and 37 GHz at horizontal and vertical polarizations. The most remarkable observation was a series of regular undulations of the signal with a significant amplitude of up to 10 K at 37 GHz and a quasi-period of 30–50 m. In contrast, the variability at longer length scales seemed to be weak in the investigated area and the mean brightness temperature was close to AMSR-E and WindSat satellite observations for all the frequencies and polarisations. To establish a link between the snow characteristics and undulation-scale variations of microwave emission, we collected detailed snow grain size and density profiles to run the DMRT-ML microwave emission model at two points where opposite extrema of brightness temperature were observed. The numerical simulations revealed that the difference in density of the upper first meter of the snowpack explained most of the brightness temperature variations. In addition, we found in the field that these variations of density were linked to the hardness of the snowpack. Areas of hard snow – probably formed by the wind – were clearly visible and covered as much as 39% of the investigated area. Their brightness temperature was higher than in normal areas. This result implied that the microwave emission measured by satellites over Dome C is more complex than expected and very likely depends on the areal proportion of the two different types of areas having distinct snow properties.
Programme: 902
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Verfaillie D, Fily M, Le Meur E, Magand O, Jourdain B, Arnaud L, Favier V, . (2012). Snow accumulation variability in Adelie Land (East Antarctica) derived from radar and firn core data. A 600 km transect from Dome C
. The Cryosphere Discuss., 6(4), 2855–2889.
Abstract: The mass balance of ice sheets is an intensively studied topic in the context of global change and sealevel rise. However – particularly in Antarctica – obtaining mass balance estimates remains difï¬cult due to various logistical problems. In the framework of the TASTE-IDEA (Trans-Antarctic Scientiï¬c Traverses Expeditions – Ice Divide of East Antarctica) program, an International Polar Year project, continuous ground penetrating radar (GPR) measurements were carried out during a traverse in Adelie Land (East Antarctica) during the 2008–2009 austral summer between the Italian–French Dome C (DC) polar plateau site and French Dumont D’Urville (DdU) coastal station. The aim of this study was to process and interpret GPR data in terms of snow accumulation, to analyse its spatial and temporal variability and compare it with historical data and modelling. The focus was on the last 300 yr, from the preindustrial period to recent times. Beta-radioactivity counting and gamma spectrometry were applied to cores at the LGGE laboratory, providing a depth–age calibration for radar measurements. Over the 600 km of usable GPR data, depth and snow accumulation were determined with the help of three distinct layers visible on the radargrams (≈ 1730, 1799 and
1941 AD). Preliminary results reveal a gradual increase in accumulation towards the coast (from ≈ 3 cm w.e. a-1 at Dome C to ≈ 17 cm w.e. a-1 at the end of the transect) and previously undocumented undulating structures between 300 and 600 km from DC. Results agree fairly well with data from
previous studies and modelling. Drawing ï¬nal conclusions on temporal variations is difï¬cult because of the margin of error introduced by density estimation. This study should have various applications, including model validation.
Programme: 411
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Cavitte M G P, Blankenship D D, Young D A, Siegert M J, Le Meur E, . (2013). Radar stratigraphy connecting Lake Vostok and Dome C, East Antarctica, constrains the EPICA/DMC ice core time scale
. The Cryosphere Discuss., 7(1), 321–342.
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Barral H, Genthon C, Trouvilliez A, Brun C, Amory C, . (2014). Blowing snow at D17, Adélie Land, Antarctica: atmospheric moisture issues
. The Cryosphere Discuss., 8(3), 2759–2798.
Abstract: Three years of blowing snow and meteorological observations have been collected along a 7 m mast at site D17 in coastal Adélie Land, Antarctica. This is a region particularly exposed to katabatic winds. The atmospheric surface layer is often close to saturation because of the sublimation of the airborne snow particles. A systematic dry bias results in atmospheric models that ignore blowing snow and its moistening effects, and in meteorological analyses that use such model. The Crocus snow-pack model, including a parameterization for the erosion of surface snow by wind, reproduces the observed march of snow accumulation and ablation if the observed meteorology is used as input. Because of subsaturation, a 2.5 fold increase in surface sublimation is obtained if analyzed surface air meteorology is used. The sublimation obtained in the Crocus model poorly agrees with the moisture fluxes evaluated using the profile method along the mast. Moisture gradients are very weak, particularly when blowing snow saturates the air, to a point where measurement accuracy is an issue. Using the profile method, the measurement uncertainties are strongly amplified in case of strong wind. In such conditions, a single level bulk parameterization with surface energy balance closure as in the Crocus model is preferred. At D17, more than half of the total snow fall is removed by erosion and sublimation, both at the surface and, mainly, of airborne snow particles.
Programme: 411
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