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Antarctic Ice Sheet and Radar Altimetry: A Review  [PDF]
Frédérique Rémy,Soazig Parouty
Remote Sensing , 2009, DOI: 10.3390/rs1041212
Abstract: Altimetry is probably one of the most powerful tools for ice sheet observation. Our vision of the Antarctic ice sheet has been deeply transformed since the launch of the ERS1 satellite in 1991. With the launch of ERS2 and Envisat, the series of altimetric observations now provides 19 years of continuous and homogeneous observations that allow monitoring of the shape and volume of ice sheets. The topography deduced from altimetry is one of the relevant parameters revealing the processes acting on ice sheet. Moreover, altimeter also provides other parameters such as backscatter and waveform shape that give information on the surface roughness or snow pack characteristics.
PROGRESS IN THE RESEARCH ON ANTARCTIC ICE SHEET IN RELATION TO GLABAL CHANGE
揭示气候变化的南极冰盖研究新进展

Qin Dahe,Ren Jiawen,Xiao Cunde,
秦大河
,任贾文

地理学报 , 1995,
Abstract: The Antarctic ice sheet is the largest grounded ice in the world, which occupies more than three fourths of the Earth's fresh water and contains sufficient ice to raise world-wide sea level by more than 60m if melted completely. Since major interactions between the ice sheet, atmosphere and oceans affect the entire global system, the ice sheet plays a critical role in global change. The ice sheet not only respond to climatic change but also influence climate greatly through feedback. Any changes in mass balance of the ice sheet may be of importance to global sea-level change. The special geographic location, ice thickness, snow accumulation rate and surface temperature combine to make the Antarctic ice sheet the storehousee of the longest and potentially most diverse ice records on earth. The global changee information preserved in the ice sheet is unique because of its wide range of direct and proxy measures, long time-scale. and high resolution and fidelity. During the past decades, research on the Antarctic ice sheet has made great progress both in investigation of the ice sheet and recovery of climatic and environmental record preserved in it, primarily due to modern technological advances. To date the form and extent of the surface features of the ice sheet have been defined much clear, and a lot of data on the ice thickness and the sub-ice bedrock topography (and hence estimation of the ice volum) has been acquired. Studies of ice cores taken from the ice sheet have already provided climatic and environmental records over the last ice age cycle. Some achivements in monitoring of the greenhouse gases and the anthropogenic pollutants have also been made. Since the global change is becoming increasingly important to the human race. to further understand the ice sheet and investigate the ralationships between the ice. atmosphere and oceans and to monitor and detect the global change in the ice sheet will be the front of Antarctic research in future. More widespread international and multiple disciplinees cooperation is certainly emphasized in the coming programs .
The Determination of Promising Mineral Zones in 1:100,000 Varamin Sheet Based on Geochemical Studies (Heavy Minerals)  [PDF]
Seyyed Reza Mortazavi, Ghodratollah Mohammadi
Open Journal of Geology (OJG) , 2016, DOI: 10.4236/ojg.2016.68057
Abstract: In many parts of the world, data obtained from geochemical exploration of stream sediments are integrated with geological and geophysical data as one of the most efficient methods of exploring potential deposits at regional and semi-detailed scales. The aim of regional investigation is to study large areas to identify anomalies that might have been arisen from increased concentrations of an element or some elements in a region. A total of 78 geochemical samples were taken from Varamin sheet to identify regions of anomalies. The following information was used to perform a detailed geochemical exploration, in particular for geochemical sampling. 1) 1:100,000 geological map of Varamin. 2) 1:50,000 topographic maps of the region. 3) 1:100,000 airborne geophysical map of the region to locate shallow intrusions and hidden faults. The sampling network was designed using the above data and the analysis of 1:500,000 topographic maps. The sampling density was higher around faults and apparent and hidden intrusions, and lower in plains and lowlands.
Getting around Antarctica: new high-resolution mappings of the grounded and freely-floating boundaries of the Antarctic ice sheet created for the International Polar Year  [PDF]
R. Bindschadler,H. Choi,A. Wichlacz,R. Bingham
The Cryosphere , 2011, DOI: 10.5194/tc-5-569-2011
Abstract: Two ice-dynamic transitions of the Antarctic ice sheet – the boundary of grounded ice features and the freely-floating boundary – are mapped at 15-m resolution by participants of the International Polar Year project ASAID using customized software combining Landsat-7 imagery and ICESat/GLAS laser altimetry. The grounded ice boundary is 53 610 km long; 74 % abuts to floating ice shelves or outlet glaciers, 19 % is adjacent to open or sea-ice covered ocean, and 7 % of the boundary ice terminates on land. The freely-floating boundary, called here the hydrostatic line, is the most landward position on ice shelves that expresses the full amplitude of oscillating ocean tides. It extends 27 521 km and is discontinuous. Positional (one-sigma) accuracies of the grounded ice boundary vary an order of magnitude ranging from ±52 m for the land and open-ocean terminating segments to ±502 m for the outlet glaciers. The hydrostatic line is less well positioned with errors over 2 km. Elevations along each line are selected from 6 candidate digital elevation models based on their agreement with ICESat elevation values and surface shape inferred from the Landsat imagery. Elevations along the hydrostatic line are converted to ice thicknesses by applying a firn-correction factor and a flotation criterion. BEDMAP-compiled data and other airborne data are compared to the ASAID elevations and ice thicknesses to arrive at quantitative (one-sigma) uncertainties of surface elevations of ±3.6, ±9.6, ±11.4, ±30 and ±100 m for five ASAID-assigned confidence levels. Over one-half of the surface elevations along the grounded ice boundary and over one-third of the hydrostatic line elevations are ranked in the highest two confidence categories. A comparison between ASAID-calculated ice shelf thicknesses and BEDMAP-compiled data indicate a thin-ice bias of 41.2 ± 71.3 m for the ASAID ice thicknesses. The relationship between the seaward offset of the hydrostatic line from the grounded ice boundary only weakly matches a prediction based on beam theory. The mapped products along with the customized software to generate them and a variety of intermediate products are available from the National Snow and Ice Data Center.
The Amundsen Sea and the Antarctic Ice Sheet  [PDF]
Stan Jacobs,Adrian Jenkins,Hartmut Hellmer,Claudia Giulivi
Oceanography , 2012,
Abstract: A few decades ago, Antarctic ice sheets were expected to grow as the atmosphere warmed and increasing poleward moisture transport added snowfall to regions that would remain below freezing year-round. Concerns about their sensitivity to climate change were centered on air temperature and on glacially paced ice dynamics. Southern Ocean roles were relegated to iceberg transport, a mix of melting and freezing under ice shelves buffered by the frigid shelf waters generated by sea ice production, and slow sea level rise by other forcing. At that time, observations were lacking in the remote Amundsen Sea, where difficult ice conditions have vexed explorers for more than 200 years. Mapping of its ocean structure and circulation began in 1994, revealing that "warm" Circumpolar Deep Water has access to its continental shelf. Glacially scoured troughs in the seafloor provide conduits for that seawater to melt regional ice shelves far more rapidly near their deep grounding lines. Coincident satellite data showed the ice shelves were thinning, in turn leading to accelerated glacier flow and loss of grounded ice to the sea. Repeated measurements and modeling suggest ocean changes that could impact the stability of the marine-based West Antarctic Ice Sheet.
Variation of Stable Isotopes in Surface Snow along a Traverse from Coast to Plateau''s interior in East Antarctica and Its Climatic Significance
Variation of Stable Isotopes in Surface Snow along a Traverse from Coast to Plateau’s interior in East Antarctica and Its Climatic Significance

Jian ChengKang,Jean Jouzel,Michel Stievenard,DaHe Qin,LeiBao Liu,DaLi Wang,ZhongQin Li,Jun Li,
JianCheng Kang
,Jean Jouzel,Michel Stievenar,DaHe Qin,LeiBao Liu,DaLi Wang,ZhongQin Li,Jun Li

寒旱区科学 , 2009,
Abstract: The variations of stable water isotopes of surface snow in east Antarctic Ice Sheet, are discussed by a total of 251 samples, which were taken along a 330 km traverse from Zhongshan Station to the outer edge of the Antarctic plateau and from four snow pits excavated along the route. Analyzing results of the samples showed the expected linear relationship between the parameters ?D and ?18O with slope S1 and intercept d1. When the data set was examined using a sliding window with a width of 5 samples, it was found that there were two areas with different ratios of S1 and d1. The boundary between these two areas occurred at an elevation of about 2,000 m, suggesting two different sources of water vapour. Nearly half (47%) of the fresh-snow samples had negative deuterium excess (d=?D? 8?18O) values, but few of the snow pit samples did, suggesting that variations of ? are quickly smoothed by isotopic diffusion in the near-surface firn. Analysis of the phase relationship between ?D and deuterium excess in the snow pit stratigraphies showed that they were mostly in phase from Jan. 1994 to Sept. 1995, but mostly out of phase from Sept. 1995 to Jan. 1997
Air-snow transfer of nitrate on the East Antarctic Plateau – Part 1: Isotopic evidence for a photolytically driven dynamic equilibrium  [PDF]
J. Erbland,W. C. Vicars,J. Savarino,S. Morin
Atmospheric Chemistry and Physics Discussions , 2012, DOI: 10.5194/acpd-12-28559-2012
Abstract: Here we report the measurement of the comprehensive isotopic composition (δ15N, Δ17O and δ18O) of nitrate at the air–snow interface at Dome C, Antarctica (DC, 75° 06' S, 123° 19' E) and in snow pits along a transect across the East Antarctic Ice Sheet (EAIS) between 66° S and 78° S. For each of the East Antarctic snow pits in most of which nitrate loss is observed, we derive apparent fractionation constants associated with this loss as well as asymptotic values of nitrate concentration and isotopic ratios below the photic zone. Nitrate collected from snow pits on the plateau have average apparent fractionation constants of ( 59±10)‰, (+2.0±1.0)‰ and (+8.7±2.4)‰, for δ15N, Δ17O and δ18O, respectively. In contrast, snow pits sampled on the coast show distinct isotopic signatures with average apparent fractionation constants of ( 16±14)‰, ( 0.2±1.5)‰ and (+3.1±5.8)‰, for δ15N, Δ17O and δ18O, respectively. From a lab experiment carried out at DC in parallel to the field investigations, we find that the 15N/14N fractionation associated with the physical release of nitrate is ( 8.5±2.5)‰, a value significantly different from the modelled estimate previously found for photolysis ( 48‰, Frey et al., 2009) when assuming a Rayleigh-type process. Our observations corroborate that photolysis is the dominant nitrate loss process on the East Antarctic Plateau, while on the coast the loss is less pronounced and could involve both physical release and photochemical processes. Year-round isotopic measurements at DC show a close relationship between the Δ17O of atmospheric nitrate and Δ17O of nitrate in skin layer snow, suggesting a photolytically-driven isotopic equilibrium imposed by nitrate recycling at this interface. The 3–4 weeks shift observed for nitrate concentration in these two compartments may be explained by the different sizes of the nitrate reservoirs and by deposition from the atmosphere to the snow. Atmospheric nitrate deposition may lead to fractionation of the nitrogen isotopes and explain the almost constant shift on the order of 25‰ between the δ15N values in the atmospheric and skin layer nitrate at DC. Asymptotic δ15N(NO3 ) values and the inverse of snow accumuation rates are correlated (ln(δ15N(as.) + 1) = (5.76±0.47) · (kg m 2 a 1/A) + (0.01±0.02)) confirming the strong relationship between the snow accumulation rate on the residence time of nitrate in the photic zone and the degree of isotopic fractionation, consistent with with previous observations by Freyer et al. (1996). Asymptotic Δ17O(NO3 ) values on the plateau are smaller compared to the
A new coupled ice sheet/climate model: description and sensitivity to model physics under Eemian, Last Glacial Maximum, late Holocene and modern climate conditions
J. G. Fyke, A. J. Weaver, D. Pollard, M. Eby, L. Carter,A. Mackintosh
Geoscientific Model Development (GMD) & Discussions (GMDD) , 2011, DOI: 10.5194/gmd-4-117-2011
Abstract: The need to better understand long-term climate/ice sheet feedback loops is motivating efforts to couple ice sheet models into Earth System models which are capable of long-timescale simulations. In this paper we describe a coupled model that consists of the University of Victoria Earth System Climate Model (UVic ESCM) and the Pennsylvania State University Ice model (PSUI). The climate model generates a surface mass balance (SMB) field via a sub-gridded surface energy/moisture balance model that resolves narrow ice sheet ablation zones. The ice model returns revised elevation, surface albedo and ice area fields, plus coastal fluxes of heat and moisture. An arbitrary number of ice sheets can be simulated, each on their own high-resolution grid and each capable of synchronous or asynchronous coupling with the overlying climate model. The model is designed to conserve global heat and moisture. In the process of improving model performance we developed a procedure to account for modelled surface air temperature (SAT) biases within the energy/moisture balance surface model and improved the UVic ESCM snow surface scheme through addition of variable albedos and refreezing over the ice sheet. A number of simulations for late Holocene, Last Glacial Maximum (LGM), and Eemian climate boundary conditions were carried out to explore the sensitivity of the coupled model and identify model configurations that best represented these climate states. The modelled SAT bias was found to play a significant role in long-term ice sheet evolution, as was the effect of refreezing meltwater and surface albedo. The bias-corrected model was able to reasonably capture important aspects of the Antarctic and Greenland ice sheets, including modern SMB and ice distribution. The simulated northern Greenland ice sheet was found to be prone to ice margin retreat at radiative forcings corresponding closely to those of the Eemian or the present-day.
A new coupled ice sheet-climate model: description and sensitivity to model physics under Eemian, Last Glacial Maximum, late Holocene and modern climate conditions  [PDF]
J. G. Fyke,A. J. Weaver,D. Pollard,M. Eby
Geoscientific Model Development Discussions , 2010, DOI: 10.5194/gmdd-3-1223-2010
Abstract: The need to better understand long-term climate/ice sheet feedback loops is motivating efforts to couple ice sheet models into Earth System models which are capable of long-timescale simulations. In this paper we describe a coupled model, that consists of the University of Victoria Earth System Climate Model (UVic ESCM) and the Pennsylvania State University Ice model (PSUI). The climate model generates a surface mass balance (SMB) field via a sub-gridded surface energy/moisture balance model that resolves narrow ice sheet ablation zones. The ice model returns revised elevation, surface albedo and ice area fields, plus coastal fluxes of heat and moisture. An arbitrary number of ice sheets can be simulated, each on their own high-resolution grid and each capable of synchronous or asynchronous coupling with the overlying climate model. The model is designed to conserve global heat and moisture. In the process of improving model performance we developed a procedure to account for modelled surface air temperature (SAT) biases within the energy/moisture balance surface model and improved the UVic ESCM snow surface scheme through addition of variable albedos and refreezing over the ice sheet. A number of simulations for late Holocene, Last Glacial Maximum (LGM), and Eemian climate boundary conditions were carried out to explore the sensitivity of the coupled model and identify model configurations that best represented these climate states. The modelled SAT bias was found to play a significant role in long-term ice sheet evolution, as was the effect of refreezing meltwater and surface albedo. The bias-corrected model was able to reasonably capture important aspects of the Antarctic and Greenland ice sheets, including modern SMB and ice distribution. The simulated northern Greenland ice sheet was found to be prone to ice margin retreat at radiative forcings corresponding closely to those of the Eemian or the present-day.
Variability of black carbon deposition to the East Antarctic Plateau, 1800–2000 AD
M. M. Bisiaux, R. Edwards, J. R. McConnell, M. R. Albert, H. Anschütz, T. A. Neumann, E. Isaksson,J. E. Penner
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2012,
Abstract: Refractory black carbon aerosols (rBC) from biomass burning and fossil fuel combustion are deposited to the Antarctic ice sheet and preserve a history of emissions and long-range transport from low- and mid-latitudes. Antarctic ice core rBC records may thus provide information with respect to past combustion aerosol emissions and atmospheric circulation. Here, we present six East Antarctic ice core records of rBC concentrations and fluxes covering the last two centuries with approximately annual resolution (cal. yr. 1800 to 2000). The ice cores were drilled in disparate regions of the high East Antarctic ice sheet, at different elevations and net snow accumulation rates. Annual rBC concentrations were log-normally distributed and geometric means of annual concentrations ranged from 0.10 to 0.18 μg kg 1. Average rBC fluxes were determined over the time periods 1800 to 2000 and 1963 to 2000 and ranged from 3.4 to 15.5 μg m 2 a 1 and 3.6 to 21.8 μg m 2 a 1, respectively. Geometric mean concentrations spanning 1800 to 2000 increased linearly with elevation at a rate of 0.025 μg kg 1/500 m. Spectral analysis of the records revealed significant decadal-scale variability, which at several sites was comparable to decadal ENSO variability.
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