冰芯和台站记录的近50 a来东南极冰盖边缘地区气候变化格局

对取自东南极冰盖Lambert冰流东、西两侧共支雪芯,恢复了过去50 a来稳定同位素温度序列和积累率序列.对比发现,位于Lambert冰流东侧,即位于Wilks地和Princess Elizabeth 地的5支雪芯(GC₃0, GD03, GD15, DT001和DT085),过去50 a来积累率总体为上升趋势,δ¹⁸O上升速率介于0.34～2.6 kg·m^-2·a^-1; 稳定同位素显示其气温亦呈整体上升趋势, 上升速率介于0‰～0.02‰·a^-1. 但对位于Lamb ert冰流西侧, 即位于Dronning Maud地、Mizuho高原和Kamp地的5支雪芯(Core E,DML 05,W2 00, LGB16和MGA),过去50 a来积累率总体为下降趋势,下降速率介于-0.01～-2.3 6 kg·m^-2·a^-1; 稳定同位素温度变化则十分复杂:Dronning Maud 地西侧为上升, Mizuho高原和Kamp地为下降或变化不明显. 分布于LGB两侧沿岸气象站记录也印证了上述格局. 这种格局可能是南大洋独特的环流形式-环南极波(ACW)-在特殊地形( 如大的冰盆)影响下, 在南极冰盖边缘的表现形式.

Climate Regime of the Coastal Antarctic Ice Sheet over the Past 50 Years Indicated by the Ice-core and Meteorological Records

Ten firn cores, in which five locates at the eastern side and another five at the western side of Lambert Glacier basin (LGB), were contrasted for their records of snow accumulation and isotopic temperature for the recent 50 years. It is demonstrated that snow accumulation at the five sites over the eastern side (i.e., GC₃0, GD03, GD15, DT001 and DT085, which locate at Wilks Land and Princess Elizabeth Land) of LGB increases, whereas those at the western side (i.e., Core E, DML05, W200, LGB16 and MGA, which locate at Dronning Maud Land, Mizuho Plateau and Kamp Land) decreases. For the past decades, the increasing rate at the eastern side was between 0.34～2.36 kg·m^-2·a^-1, and the decreasing rate at the western side between -0.01～-2.36 kg·m^-2·a^-1. Temperatures at the eastern LGB were also increasing, with the rate around 0.02 a^-1. But at the western LGB it was much more complex. Instrumental temperature records at coastal stations confirm this complexity;Although statistic study and modeling display that both surface temperature and accumulation rate display increasing trends in Antarctic ice sheet for the period 1950-2000, the regional temperature distribution is much different, even converse over in some geographical units. It is believed that the ice-core records at Wilks Land and Princess Elizabeth Land reflect the real variations of sea surface temperature and moisture change in the southern India Ocean. But for the Kamp Land and Dronning Maud Land, varied circulation pattern complexes the climate;The International Trans-Antarctic Scientific Expedition has its initial aim to reveal an overall spatial pattern of climatic change on Antarctic ice sheet for the past 200 years. This study will re-confirms the importance of continental to regional scaled circulation to annual-decadal scaled climatic change in Antarctica.