祁连山区雪冰反照率变化及其对冰川物质平衡的影响

Snow/ice albedo variation and its impact on glacier mass balance in the Qilian Mountains

雪冰反照率能够改变冰川表面能量收支平衡,是影响冰川消融的重要因素之一。利用祁连山地区冰川面积矢量数据、MODIS逐日积雪反照率、气温和降水以及冰川物质平衡等数据,探讨了祁连山典型冰川区雪冰反照率特征及其对冰川物质平衡的影响。结果表明:祁连山地区冰川多年平均反照率为0.532,冰川区面积大小与其多年平均反照率之间呈显著正相关(R2=0.16,P<0.05,N=91),即冰川面积缩减1km^(2),对应的平均反照率下降0.0025。祁连山老虎沟12号冰川反照率在夏季有明显的海拔效应,且强于其他时段,达到0.047·(100m)^(-1)。典型冰川年均物质平衡量与冰川表面夏季(6—8月)平均反照率之间存在显著的正相关关系,老虎沟12号冰川和七一冰川决定系数R2分别达到了0.48(P<0.05)和0.66(P<0.05)。冰川表面夏季平均反照率这一指标能够较好地衡量青藏高原北部祁连山地区冰川物质平衡的变化。

Snow/ice albedo can affect the glacier surface energy budget,making it an important factor to impact glacier melt.Based on vector data of glacierized areas,MODIS daily snow albedo,air temperature and precipitation,and glacier mass balance in the Qilian Mountains,this study addressed the spatial-temporal characteristics of snow/ice albedo,and the relationship between glacier mass balance and snow/ice albedos.The results indicated an average albedo in the study area was 0.532.A positive correlation existed between glacierized area and annual averaged albedo,namely the glacierized area decreased by 1 km^(2 )will cause a reduction of albedo by 0.0025.For the typical glaciers of Laohugou Glacier No.12 and Qiyi Glacier,average albedo during summer(June to August)was significantly positive correlated with annual glacier mass balance,coefficient of determination reaching 0.48(P<0.05)and 0.66(P<0.05),respectively.Such result indicated that variation of albedo played a great impact on smaller glaciers,which will further enhance the retreat of smaller glaciers.The average albedo during summer can be considered as an effective proxy for changes of glacier mass balance.