藏北高原多年冻土区地表反照率特征分析

The Characteristics of Surface Albedo in Permafrost Regions of Northern Tibetan Plateau

利用青藏高原冰冻圈观测研究站西大滩、五道梁和唐古拉自动气象站(AWS)2006—2007年的辐射观测资料,分析了藏北高原多年冻土区不同下垫面的地表反照率特征.结果表明:该地区地表反照率在四季都表现出明显的日变化特征,呈U形,早晚大,中午小.日平均和月平均地表反照率有相同的年变化特征,且冬半年的地表反照率远远大于夏半年.受积雪的影响,地表反照率年均值较高,夏季最小,冬季最大,春季大于秋季.针对3种不同植被类型的下垫面,在四季反照率都有高寒草甸(唐古拉)<高寒草原(西大滩)<荒漠草原(五道梁)的特点.

Based on the observed radiation data at automatic weather stations including Xidatan（XDT）,Tanggula（TGL） and Wudaoliang（WDL）（operated by Cryosphere Research Station on Qinghai-Xizang Plateau,CAS） in 2006 and 2007,characteristics of surface albedo under different surface conditions in permafrost regions of Northern Tibetan Plateau are analyzed.The results indicated that surface albedo in these regions shows obvious diurnal variation characteristics in the four seasons.The diurnal variation curves present ＂U＂shapes.The values of surface albedo are larger at sunrise and sunset and smaller at noon.The daily and monthly mean values of surface albedo have similar annual variation characteristics.The values of surface albedo are much larger in winter half-year than summer half-year.By the impact of snow cover,the annual average of surface albedo in these regions is larger than other regions of the plateau.The values decrease in the following order： winter,spring,autumn and summer.Under different surface conditions,the values of surface albedo rank as alpine meadow（TGL）alpine grassland（XDT）desert steppe（WDL）.