天山南坡科契卡尔巴西冰川消融期雪面能量平衡研究

根据2005年6～9月的野外观测资料,计算了天山南坡科契卡尔巴西冰川积雪表面的能量平衡各分量,其中感热和潜热采用空气动力学-梯度方法计算得到,净辐射由观测获得.结果表明,消融期净辐射是雪面最主要的能量来源,占能量收入的81.4%,平均值为63.3 W.m-2;其次为感热供热,占18.6%,为14.4 W.m-2.吸收的热量主要通过融化和蒸发两种方式消耗,融化和蒸发耗热分别为54.0 W.m-2和23.0 W.m-2,占能量总支出的69.5%和29.7%,剩下的0.8%由感热消耗.在积雪表面的能量组成中,感热值在6月和9月较大而8月较小;对于潜热来说,6月潜热交换绝对值最大,蒸发最强烈,这与6月风速大且天气晴好有关.另一方面,净辐射值较大的6月和9月融化热较多,说明此时段冰川消融较为强烈.

Snow Surface Energy Balance over the Ablation Period on the Keqicar Baxi Glacier in the Tianshan Mountains

Meteorlological data were recorded(from June 16 to September 7,2005) at 4 200 m a.s.l.on the Keqicar Baxi Glacier in the Tarim River basin of Northwest China.The net radiation was directly measured,and the turbulent fluxes were calculated from the bulk aerodynamic approach.During the period under consideration the net radiation and the sensible turbulent heat fluxes were energy sources to the glacier surface,and net radiation is the primary energy source,accounting for 81.4% with its value of 63.3W5m-2.The rest energy source is provided by the sensible turbulent heat flux,accounting for 22%.Energy is consumed mainly by snow melting and the evaporation.The energy for snow melting and the evaporation accounted for 69.5% and 29.7% for the total energy with their values 54.0 W5m-2 and 23.0 W5m-2,respectively,and the rest is consumed by sensible turbulent flux.The sensible turbulent flux is always positive,which means that the surface gain energy through sensible heat exchange.The value of sensible turbulent flux is larger on the middle and last ten days of June, but smaller in August.The latent turbulent flux is negative and its value reaches its maximum on the middle and last ten days of June,because of the strongest evaporation during this period,in relation to the high values of wind velocity and clear weather on the middle and last ten days of June.It is also found that the melting heat values were high on the middle and last ten days of June and the first ten days of September,showing that there was an intensive ablation period of glacier.