A 109.9 m ice core was extracted at a location about 300 m away from the Dome A summit （80°00′S, 77°21″E） by the Chinese team of the International Trans-Antarctic Science Expedition （ITASE） during the ...A 109.9 m ice core was extracted at a location about 300 m away from the Dome A summit （80°00′S, 77°21″E） by the Chinese team of the International Trans-Antarctic Science Expedition （ITASE） during the 21st Chinese National Antarctica Research Expedition （CHINARE） in January 2005. Two independent methods were used for dating the ice core, volcanic event markers shown by prominent non-sea-salt sulfate （nss-SO4^2-） and the Herron and Langway （H-L） firn densification model. Six promi- nent volcanic events （Agung 1963 AD, Tambora 1815 AD, Kuwae 1453 AD, Unknown 1259 AD, Taupo 186 AD and Pinatubo 1050 BC） were identified by comparison with other Antarctic ice cores. Based on the mean accumulation rates be- tween adjacent events, we estimate the age at the tim pore close-off depth （102 m） was 3516±100 a BP. This is the oldest close-off age ever reported from the Antarctic and the Greenland ice sheets. Calculations using the H-L model show that the age at the same depth is 3581±100 a BP. The two dating techniques differ by 65 years, or -1.8% of the record. We calculated the bottom age of the ice core as 4009±150 a BP using the volcanic dating method and 4115±150 a BP using the H-L model method.展开更多
Dome A, the highest dome of East Antarctic Ice Sheet, is being an area focused by international Antarctic community after Chinese Antarctic Expedition finally reached there in 2005, and with the ongoing International ...Dome A, the highest dome of East Antarctic Ice Sheet, is being an area focused by international Antarctic community after Chinese Antarctic Expedition finally reached there in 2005, and with the ongoing International Polar Year （IPY） during August 2007. In this paper two data processing methods are used together to generate two 100-m cell size digital elevation models （DEMs） of the Dome A region （Dome A-DEM） by using Cokriging method to interpolate the ICESat GLAS data, with Ihde-DEM as a constraint. It provides fundamental data to glaciological and geophysical investigation in this area. The Dome A-DEM was applied to determining the ice-sheet surface elevations and coordinates of the south and north summits, defining boundaries of basins and ice ftowlines, deducing subglacial topography, and mapping surface slope and aspect in Dome A region. The DEM shows there are two （north and south） summits in Dome A region. The coordinate and the surface elevation of the highest point （the north summit） are 80°21＇29.86＂S, 77°21＇50.29＂E and 4092.71±1.43m, respectively. The ice thickness and sub-ice bedrock elevation at north summit are 2420m and 1672m, respectively. Dome A region contains four drainage basins that meet together near the south summit. Ice ftowlines, slope and aspect in detail are also derived using the DEM.展开更多
基金supported by National Natural Scientific Foundation of China (Grant Nos.40776002,40825017,41171052)the Hundred Talent Project of Chinese Academy of Sciences,the Polar Scientific Explore Organizing Committee Foundation (Grant Nos. 20080202,0852H71001)State Oceanic Administration of People’s Republic of China Project on Climate in Polar Regions (Grant Nos.CHINARE2012-04-04 and CHINARE2012- 02-02)
文摘A 109.9 m ice core was extracted at a location about 300 m away from the Dome A summit （80°00′S, 77°21″E） by the Chinese team of the International Trans-Antarctic Science Expedition （ITASE） during the 21st Chinese National Antarctica Research Expedition （CHINARE） in January 2005. Two independent methods were used for dating the ice core, volcanic event markers shown by prominent non-sea-salt sulfate （nss-SO4^2-） and the Herron and Langway （H-L） firn densification model. Six promi- nent volcanic events （Agung 1963 AD, Tambora 1815 AD, Kuwae 1453 AD, Unknown 1259 AD, Taupo 186 AD and Pinatubo 1050 BC） were identified by comparison with other Antarctic ice cores. Based on the mean accumulation rates be- tween adjacent events, we estimate the age at the tim pore close-off depth （102 m） was 3516±100 a BP. This is the oldest close-off age ever reported from the Antarctic and the Greenland ice sheets. Calculations using the H-L model show that the age at the same depth is 3581±100 a BP. The two dating techniques differ by 65 years, or -1.8% of the record. We calculated the bottom age of the ice core as 4009±150 a BP using the volcanic dating method and 4115±150 a BP using the H-L model method.
基金Under the auspices of the National Natural Science Foundation of China (No. 40471028, No. 40476005)ShanghaiShu Guang Project (No. 05SG46)
文摘Dome A, the highest dome of East Antarctic Ice Sheet, is being an area focused by international Antarctic community after Chinese Antarctic Expedition finally reached there in 2005, and with the ongoing International Polar Year （IPY） during August 2007. In this paper two data processing methods are used together to generate two 100-m cell size digital elevation models （DEMs） of the Dome A region （Dome A-DEM） by using Cokriging method to interpolate the ICESat GLAS data, with Ihde-DEM as a constraint. It provides fundamental data to glaciological and geophysical investigation in this area. The Dome A-DEM was applied to determining the ice-sheet surface elevations and coordinates of the south and north summits, defining boundaries of basins and ice ftowlines, deducing subglacial topography, and mapping surface slope and aspect in Dome A region. The DEM shows there are two （north and south） summits in Dome A region. The coordinate and the surface elevation of the highest point （the north summit） are 80°21＇29.86＂S, 77°21＇50.29＂E and 4092.71±1.43m, respectively. The ice thickness and sub-ice bedrock elevation at north summit are 2420m and 1672m, respectively. Dome A region contains four drainage basins that meet together near the south summit. Ice ftowlines, slope and aspect in detail are also derived using the DEM.
