东南极冰盖Lambert冰川流域300年来降雪记录

THE SNOWFALL HISTORY OF LAMBERT GLACIER BASIN DURING THE PAST 300 YEARS INFERRED FROM AN ICE CORE AT LGB69, EAST ANTARCTICA

利用中国第18次南极考察队内陆冰盖考察队获得的102m冰芯资料，恢复了南极洲Lambert冰川流域东侧地区300年来的降雪量／雪积累率变化情况，并使用Nye模型和D—J模型进行了较准。结果表明，1708～2001年间年降雪量平均为261．7±69．7kg／m2a，该区域的年降雪量变化可分为1863年前和之后两段，1863年前年降雪量变化较小，平均为264．8±63．4kg／m2a；之后则变化快速，可能与全球气温快速变化和Prydz湾海冰面积变化有关。另外，通过模型对比发现，南极冰盖运动对长时间序列的冰芯降水记录恢复影响较大，在LGB69102m深度处可达6．3％（D—J模型），需引起重视。

Based on a 102m ice core drilled at LGB69 （70°50′06.6″S, 77°04′28.9″E; 1850m a. s. 1.） of EastAntarctica, by 18th Chinese National Antarctic Research Expedition, we reconstructed the snowfall/accumulation history during 1708- 2001 by volcanic events and chemical layers method. The bottom of the ice core was dated into 1708±2 A.D. Then, the Nye model and D-J model were applied to calibrate the annual mean snowfall to eliminate the ice stretch effect by ice flow. The results shows that the annual mean snowfall was 261.7±69.7kg/m2 .a during 1708-2001, and can be divided into two main periods： one is before 1863 when the annual mean snowfall is 264.8±63.4kg/m2.a and the variation of snowfall is quite stable; then after 1863, the annual mean snowfall changes fast due to the rapid climate change of earth surface and sea ice change of adjacent ocean （Prydz Bay）. This trend is different with most of areas of Antarctica, except Victoria Land. Besides that, we found that the ice sheet flow may lead to significant error on snowfall history reconstruction by deep ice core, LGB69 for example, the relative error could reach up to 6.3% at 102m depth by D-J model esitimation.