南极乔治王岛柯林斯冰帽冰川发育条件

EXISTING CONDITIONS OF COLLINS ICE CAP ON KING GEORGE ISLAND,ANTARCTICA

柯林斯冰帽具有显著的海洋性气候特征。据笔者实测资料 ,该冰帽冬季和夏季温度垂直递减率相当 ,为 0 .6 5℃ 1 0 0m ,冰区与无冰区间的温跃值约为 0 .3℃。年、日较差小 ,夏季气温较低 ,平衡线上夏季 (1 2月— 2月 )的平均温度为 0℃。同时 ,云雾多 ,湿度大 ,冰面接受到的太阳辐射小 ,形成了有利于冰川发育的热量条件。同时频繁的极地气旋活动给冰帽区带来了以固态降水为主的较丰沛的降水 ,成为有利于冰川发育的物质条件。夏季温度较低和年降水较丰沛是该冰帽发育有利的水热条件。

The climate in the King George Island is dominated by the frequent succession of low pressure systems which leads to a highly maritime climate. On the basis of meteorological observation,it is obtained that the surface temperature lapses in summer and winter are nearly the same,about 0 65℃/100m on the ice cap,and temperature jump is around 0.3℃. The mean annual temperature of the ice cap is relatively high,and at equilibrium-line altitude(ELA) is -3.5℃. However,since the annual temperature difference is small,the summer temperature is lower,average temperature from December to February is 0℃ at ELA. In addition,the ice cap is highly cloudy,foggy and humid that the snow surface received low amount of radiation. This heat condition is favorable to ice cap existing since it results in weak summer melt. There is relatively plentiful precipitation on Collins Ice Cap. The precipitation is 800mm at ELA,and increases rapidly with elevation,at the summit of the main dome,may over 2000mm. Most annual precipitation is solid on the ice cap,which is the mass base of glacier existing.