Duphil Romain, Possenti Philippe, Piard Luc, . (2014). A new leak-tight borehole casing at Dome Concordia station, Antarctica, for the SUBGLACIOR project
. Annals of Glaciology, 55(68), 351–354.
Abstract: In the frame of the SUBGLACIOR project, a new type of casing has been installed for testing during the 2013/14 austral summer season at Dome Concordia station, Antarctica. The SUBGLACIOR probe requires a full fluid column up to the surface, in order to circulate fluid for icechips recovery. This makes it essential that the casing is leak-tight through the porous firn column. We have evaluated existing solutions before opting to test a new method. This new system is made of polyethylene pipes which are welded together at the surface while the casing pipes are lowered into the reamed borehole. It is simple and lightweight and allows the casing to be installed quickly with
optimum chance of being leak-tight. The installed casing has been tested both with compressed air and drilling fluids and has proven to work.
Programme: 1119
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J. Mouginot, E. Rignot, Y. Gim, D. Kirchner, E. Le Meur. (2014). Low-frequency radar sounding of ice in East Antarctica and southern Greenland (Vol. 55).
Keywords: Antarctic glaciology ground-penetrating radar radio-echo sounding remote sensing
Programme: 1053
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BellotHerve, TrouvilliezAlexandre, Naaim-BouvetFlorence, GenthonChristophe, GalleeHubert, . (2011). Present weather-sensor tests for measuring drifting snow
. ANNALS OF GLACIOLOGY, 52(58), 176–184.
Abstract: In Antarctica, blowing snow accounts for a major component of the surface mass balance near the coast. Measurements of precipitation and blowing snow are scarce, and therefore collected data would allow testing of numerical models of mass flux over this region. A present weather station (PWS), Biral VPF730, was set up on the coast at Cap Prud'homme station, 5 km from Dumont d'Urville (DDU), principally to quantify precipitation. Since we expected to be able to determine blowing-snow fluxes from the PWS data, we tested this device first on our experimental site, the Lac Blanc pass. An empirical calibration was made with a snow particle counter. Although the physics of the phenomenon was not well captured, the flux outputs were better than those from FlowCapts. The first data from Antarctica were reanalyzed. The new calibration seems to be accurate for estimating the high blowing-snow flux with an interrogation of the precipitation effects.
Programme: 1013
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. (2011). Present weather-sensor tests for measuring drifting snow
. 0260-3055, 52(58), 176–184.
Abstract: In Antarctica, blowing snow accounts for a major component of the surface mass balance near the coast. Measurements of precipitation and blowing snow are scarce, and therefore collected data would allow testing of numerical models of mass flux over this region. A present weather station (PWS), Biral VPF730, was set up on the coast at Cap Prud'homme station, 5 km from Dumont d'Urville (DDU), principally to quantify precipitation. Since we expected to be able to determine blowing-snow fluxes from the PWS data, we tested this device first on our experimental site, the Lac Blanc pass. An empirical calibration was made with a snow particle counter. Although the physics of the phenomenon was not well captured, the flux outputs were better than those from FlowCapts. The first data from Antarctica were reanalyzed. The new calibration seems to be accurate for estimating the high blowingsnow flux with an interrogation of the precipitation effects.
Programme: 411
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. (2009). Full Stokes modeling of marine ice sheets: influence of the grid size (Vol. 50).
Abstract: Using the finite-element code Elmer, we show that the full Stokes modeling of the ice-sheet/ice-shelf transition we propose can give consistent predictions of grounding-line migration. Like other marine ice-sheet models our approach is highly sensitive to the chosen mesh resolution. However, with a grid size down to <5 km in the vicinity of the grounding line, predictions start to be robust because: (1) whatever the grid size (<5 km) the steady-state grounding-line position is sensibly the same (6 km standard deviation), and (2) with a grid-size refinement in the vicinity of the grounding line (200 m), the steady-state solution is independent of the applied perturbation in fluidity, provided this perturbation remains monotonic.
Programme: 1053
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Genthon C, Krinner G, Castebrunet H, . (2009). Antarctic precipitation and climate-change predictions: horizontal resolution and margin vs plateau issues
. Annals of Glaciology, 50(50), 55–60.
Abstract: All climate models participating in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, as made available by the Program for Climate Model Diagnosis and Intercomparison (PCMDI) as the Coupled Model Intercomparison Project 3 (CMIP3) archive, predict a significant surface warming of Antarctica by the end of the 21st century under a moderate (SRESA1B) greenhouse-gas scenario. All models but one predict a concurrent precipitation increase but with a large scatter of results. The models with finer horizontal resolution tend to predict a larger precipitation increase. Because modeled Antarctic surface mass balance is known to be sensitive to horizontal resolution, extrapolating predictions from the different models with respect to model resolution may provide simple yet better multi-model estimates of Antarctic precipitation change than mere averaging or even more complex approaches. Using such extrapolation, a conservative estimate of the predicted precipitation increase at the end of the 21st century is +30 kg m2a1 on the grounded ice sheet, corresponding to a >1 mm a1 sea-level rise. About three-quarters of this rise originates from the marginal regions of the Antarctic ice sheet with surface elevation below 2250 m. This is where field programs are most urgently needed to better understand and monitor accumulation at the surface of Antarctica, and to improve and verify prediction models.
Programme: 1013
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Brun Eric, Six Delphine, Picard Ghislain, Vionnet Vincent, Arnaud Laurent, Bazile Eric, Boone Aaron, Bouchard Aurelie, Genthon Christophe, Guidard Vincent, Le Moigne Patrick, Rabier Florence, Seity Yann, . (2011). Snow/atmosphere coupled simulation at Dome C, Antarctica
. Journal of Glaciology, 57(204), 721–736.
Abstract: Using a snow/atmosphere coupled model, the evolution of the surface and near-surface snow temperature is modeled at Dome C, Antarctica, during the period 20-30 January 2010. Firstly, the detailed multilayer snow model Crocus is run in stand-alone mode, with meteorological input forcing data provided by local meteorological observations. The snow model is able to simulate the evolution of surface temperature with good accuracy. It reproduces the observed downward propagation of the diurnal heatwave into the upper 50 cm of the snowpack reasonably well. Secondly, a fully coupled 3-D snow/atmosphere simulation is performed with the AROME regional meteorological model, for which the standard single-layer snow parameterization is replaced by Crocus. In spite of a poor simulation of clouds, the surface and near-surface snow temperatures are correctly simulated, showing neither significant bias nor drifts during the simulation period. The model reproduces particularly well the average decrease of the diurnal amplitude of air temperature from the surface to the top of the 45 m instrumented tower. This study highlights the potential of snow/atmosphere coupled models over the Antarctic plateau and the need to improve cloud microphysics and data assimilation over polar regions.
Programme: 1013
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. (2011). Modeling time series of microwave brightness temperature at Dome C, Antarctica, using vertically resolved snow temperature and microstructure measurements
. Journal of Glaciology, 57(201), 171–182.
Abstract: Time series of observed microwave brightness temperatures at Dome C, East Antarctic plateau, were modeled over 27 months with a multilayer microwave emission model based on dense-medium radiative transfer theory. The modeled time series of brightness temperature at 18.7 and 36.5 GHz were compared with Advanced Microwave Scanning Radiometer-EOS observations. The model uses in situ high-resolution vertical profiles of temperature, snow density and grain size. The snow grain-size profile was derived from near-infrared (NIR) reflectance photography of a snow pit wall in the range 850-1100 nm. To establish the snow grain-size profile, from the NIR reflectance and the specific surface area of snow, two empirical relationships and a theoretical relationship were considered. In all cases, the modeled brightness temperatures were overestimated, and the grain-size profile had to be scaled to increase the scattering by snow grains. Using a scaling factor and a constant snow grain size below 3 m depth (i.e. below the image-derived snow pit grain-size profile), brightness temperatures were explained with a root-mean-square error close to 1 K. Most of this error is due to an overestimation of the predicted brightness temperature in summer at 36.5 GHz.
Programme: 454
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Fourati H., Manamanni N., Afilal L., & Y. Handrich . (2009).
Abstract: Bio-logging is a new interdisciplinary research area at the intersection of animal behavior and
bioengineering. It can involve several applications such as determination of specific parameters
measurements (attitude, acceleration, and position) via a new generation of adapted-animal mechatronic systems (a.d.a.m.s.). The aim of this paper concerns the animal motion estimation problem using lowcost Micro-Electro-Mechanical-System (M.E.M.S.) sensors fusion. Generally, accurate attitude measurements are obtained using low-pass sensors such as accelerometers and magnetometers, but at quasi-static motion. In this work a state estimation algorithm is proposed, it is based on a combination of an observer and an iterated Least Squares Algorithm (I.L.S.A.). This approach fuses data from 3-axis accelerometer, 3-axis magnetometer, and 3-axis gyroscope to provide the best attitude estimation whenthe rigid body is both in static and dynamic motion. A correction stage is introduced to take into account the linear acceleration effect undergone by the rigid body. Finally, some simulation and preliminary experimental results are provided to show the efficiency of the proposed algorithm
Programme: 394
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Maj Emilie, . (2009). The Horse of Sakha: Ethnic Symbol in Post-Communist Sakha Republic (Iakutiia)
. Sibirica, 8(1), 68–74.
Abstract: This report is on contemporary processes related to horse breeding in Sakha (Iakutiia), northeastern Russia. I demonstrate the importance of the horse figure in the philosophy of the Sakha, a hunting and herding people of Siberia, as well as the parallelism between the diminishing utilitarian function of the horse and reinforcing symbolism in the post-communist context.
Programme: 1024
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