东天山庙儿沟平顶冰川钻孔温度分布特征

2005年8月在庙儿沟平顶冰川顶部海拔4 518 m处钻取了两根透底冰芯,对其中60 m的Core1冰芯钻孔利用热敏电阻温度计进行了温度测量,初步揭示了该处冰川的温度分布特征.结果显示,最低冰层温度-8.27℃出现在50 m深度处,这个深度在同类冰川中处于较低的位置;冰床底部的温度为-8.16℃,远低于压力融点.庙儿沟平顶冰川冰温的上述分布特征是在各种因素的影响下形成的,具有其独特性.这种温度分布特征,对冰芯记录过程较为有利,为恢复该地区气候与环境记录的准确性提供了保证.

Distribution Features of Borehole Temperatures in the Miaoergou Flat-topped Glacier, East Tianshan Mountains

Temperatures were measured at the ice-core borehole(4 518 m a.s.l.)in the Miaoergou flat-topped Glacier,East Tianshan Mountains,in August 2005.The length of Ice-core to the bedrock is 60 m.The primary temperature features of the Miaoergou flat-topped Glacier is revealed through the measurement.The temperature profile shows that there was a kind of warm-type ice temperature in the August and the ice temperature is always below 0℃.Ice temperature decreased linearly from -2.92℃ at 1m to-7.61℃ at 6 m deep in the surface layer,with a temperature gradient of -0.94℃·m^-1.The effects of heat conduction and meltwater refreezing contribute to the above high temperature gradient.The lowest temperature of the deep layer was -8.27℃ appeared at the depth of 50 m,which is very low among those measured in the mountain glaciers in China.The contributions of meltwater and cold advection in the glacier influence greatly the location of the lowest temperature.A minimum temperature gradient(0.011℃·m^-1)appeared from 50 m to bedrock in the profile and at the bedrock the temperature was -8.16℃,far below the melting point.From the temperature gradient near the bedrock,the geothermal flux can be inferred,which transfers heat to the bottom of glacier.It is believed that the effect of glacier movement is very small.