东南极冰盖中山站——Dome A断面路线考察的初步结果

Preliminary Results of the Inland Expeditions along a Transect from the Zhongshan Station to Dome A, East Antarctica

1996年以来 ,中国国家南极考察队连续 3次进行了南极冰盖内陆考察 ,最远点距海岸 110 0km ,海拔 3 90 0m .沿考察路线对冰盖表面地形、表面雪层特征、雪积累速率、冰体厚度和运动速度等进行现场观测 ,采集 0 6 3 3m深度雪坑样品 ,在 4个地点钻取 5 0 10 0m深度冰芯 5支 .部分资料和样品的初步分析表明 ,由于研究区域毗邻Lambert冰川和格罗夫山 ,冰面地形较多起伏 ,中段很大区域坡面朝向Lambert冰川 .自中山站向内陆 46 0km积累速率为 46 2 10kg·m-2 ·a-1(相当于 12 6 0cm厚度雪层 ) ,表面 1m深度雪的密度为 35 0 45 0kg·m-3.雪变成冰的深度 (密度达 830kg·m-3)在几个冰芯钻取地点均大约为 6 0m ,说明研究区域内雪的变质过程基本相同 .30 0km处 5 0m冰芯初步分析显示 ,过去几十年积累速率和温度均呈上升趋势 ,这虽然与南极地区其他许多地点的结果相一致 。

Chinese National Antarctic Research Expedition (CHINARE) has made three inland traverses from the Zhongshan Station to Dome A in East Antarctica since 1996, and the farthest spot arrived ( 3 900 m a.s.l.) is 1 100 km away from the coast. During these traverses, glaciological investigation (including the ice sheet topography, stratigraphy in snow pits and snow/firn cores, snow accumulation, ice sheet thickness and ice flow velocity, etc.) has been carried out. In addition, snow samples were taken from snow pits (0 6~3 3 m in depth), and five ice cores (50~100 m in length) were recovered at four sites. The primary results show that the surveyed terrain is undulatory due to its adjacence to the Lambert Glacier and Mount Grove, and its facing towards the Lambert Glacier in the middle section of the traverse. Accumulation rate derived from stake measurement within the initial 460 km route is between 12 and 60 cm snow per year, equivalent to 46 to 210 kg·m -2 ·a -1 .The average density of 1 m surface snow is between 350 and 450 kg·m -3 . The depth of pore close off (corresponding to a density of 830 kg·m -3 ) is around 60 m at all the ice core drilling sites, which implies that snow metamorphose process is similar in the whole surveyed regions. Study of the 50 m ice core (300 km away from the Zhongshan Station) indicates that both accumulation rate and air temperature has a slight increase, which is consistent to the results deduced from most Antarctic sites, but converse to the situation at the west side of the Lambert Glacier.