青藏高原冬季降雪对地面净辐射的影响  

THE INFLUENCE OF SNOW ON THE SURFACE NET RADIATION OVER QINGHAI-XIZANG PLATEAU IN WINTER

作　　者：沈志宝[1] 

机构地区：[1]中国科学院兰州高原大气物理研究所

出　　处：《高原气象》1996年第4期397-403,共7页Plateau Meteorology

基　　金：国家攀登项目

摘　　要：过去的研究结果指出，冬季青藏高原地面净辐射场是一个由地理因子决定的基本场叠加上一个降雪后地面积雪区造成的扰动场组成。为定量研究冬季青藏高原降雪对地面净辐射的扰动幅度，利用作者已经建立的冬季青藏高原雪后地面反射率与降雪量的关系以及地面无（有）积雪时计算地面净辐射的公式，计算了不同强度降雪后地面净辐射日总量及其变化。结果表明：降雪量主要控制雪后地面净辐射负值的持续时间，降雪量为２．０ｍｍ，雪后净辐射负值的持续时间约为６ｄ，降雪量为１０．０ｍｍ，可长达２０ｄ。雪后天空状况影响地面净辐射负值的大小，同样强度的降雪后，净辐射为负值的总量在晴天（日照百分率Ｓ１＝０．９）条件下约为阴天（Ｓ１＝０．２）的２倍。那曲地区冬季地面无积雪时净辐射为正值，１２月的月总量估计为２．５２—２．８８ＭＪ／ｍ２，一次１０．０ｍｍ降雪后持续约２０ｄ的地面净辐射负值的总量可达－２．６２ＭＪ／ｍ２，接近当月拉萨地面净辐射（正值）的月总量。The results of the previous studies show that the geographic distribution of surface net radiation over the Qinghai-Xizang Plateau in winter consist of a basic pattern determined by the geographic conditions and a perturbation pattern caused by snow._In order to study quantitatively the perturbations of surface net radiation caused by snow,the daily totals of surface net radiation and their variations after snow with different snowfall were calculated by use of the relationship between the albedo after snow and the snowfall,and the empirical formulae for calculating surface net radiation in cases of snowcover.The results show that the duration of negative surface net radiation after snow is determined mainly by the snowfall,6 days of the duration of negative surface net radiation may occur when snowfall is 2.0mm,but 20 days when snowfall is 10.0mm.The sunshine duration affects strongly the magnitude of surface net radiation,the absolute value of the totals of net radiation in case of the clear day ( S 1=0.9) is greater than that in cloudy day ( S 1=0.2) after snow with the same snowfall.In winter,the surface net radiation is positive in Nagqu if none of snowcover,the monthly totals of surface net radiation in December is about 2.52 2.88MJ/m 2.But the totals of the negative surface radiation budget after snow with the snowfall 10.0mm is -2.62MJ/m 2,the absolute value of which is nearly equal to the monthly totals of the positive surface radiation budget (3.19MJ/m 2) in Lhasa.

关 键 词：青藏高原 冬季 降雪 地面净辐射 

分 类 号：P422.2[天文地球—大气科学及气象学]