Numerical Simulation of Sensitivities of Snow Melting to Spectral Composition of the Incoming Solar Radiation  

作　　者：李伟平 孙菽芬 王标 刘新 

机构地区：[1]Laboratory for Climate Studies, China Meteorological Administration,Beijing 100081 [2]National Climate Center, China Meteorological Administration,Beijing 100081 [3]Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029 [4]Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100085

出　　处：《Advances in Atmospheric Sciences》2009年第3期403-412,共10页大气科学进展（英文版）

基　　金：supported by the Ministry of Science and Technology of China under Grant Nos.2007CB411505 and 2006CB403604;the Ministry of Finance of China through Grant GYHY200706005

摘　　要：Snow albedo is an important factor influencing the snow surface energy budget and snow melting, yet uncertainties remain in the calculation of spectrally resolved snow surface albedo because the spectral composition （visible versus near infrared） of the incident solar radiation is seldom available. The influence of the spectral composition of the incoming solar radiation on the snow surface albedo, snow surface energy budget, and final snow ablation is investigated through sensitivity experiments of four snow seasons at two open sites in the Alps by using a multi-layer Snow-Atmosphere-Soil-Transfer scheme （SAST）. Since the snow albedo in the near infrared （NIR） spectral band is significantly lower than that in the visible （VIS） band, and almost the entire NIR part of the solar radiation is absorbed in the top layer of the snow pack, given a fixed amount of incoming solar radiation, a lower VIS/NIR ratio implies that more NIR radiation is reaching the ground surface and more is absorbed by the top layer of the snow pack, therefore, speeding up the snow melting and increasing the surface runoff, although a lesser part of the solar radiation in the visible band is transmitted into and trapped by the sub-layer of the snow pack. The above VIS/NIR ratio effect of the incoming solar radiation can result in a couple of days difference in the timing of snow ablation and it becomes more significant in late spring when the total solar radiation is intensified with seasonal evolution. Snow aging also slightly intensifies this VIS/NIR ratio effect.Snow albedo is an important factor influencing the snow surface energy budget and snow melting, yet uncertainties remain in the calculation of spectrally resolved snow surface albedo because the spectral composition （visible versus near infrared） of the incident solar radiation is seldom available. The influence of the spectral composition of the incoming solar radiation on the snow surface albedo, snow surface energy budget, and final snow ablation is investigated through sensitivity experiments of four snow seasons at two open sites in the Alps by using a multi-layer Snow-Atmosphere-Soil-Transfer scheme （SAST）. Since the snow albedo in the near infrared （NIR） spectral band is significantly lower than that in the visible （VIS） band, and almost the entire NIR part of the solar radiation is absorbed in the top layer of the snow pack, given a fixed amount of incoming solar radiation, a lower VIS/NIR ratio implies that more NIR radiation is reaching the ground surface and more is absorbed by the top layer of the snow pack, therefore, speeding up the snow melting and increasing the surface runoff, although a lesser part of the solar radiation in the visible band is transmitted into and trapped by the sub-layer of the snow pack. The above VIS/NIR ratio effect of the incoming solar radiation can result in a couple of days difference in the timing of snow ablation and it becomes more significant in late spring when the total solar radiation is intensified with seasonal evolution. Snow aging also slightly intensifies this VIS/NIR ratio effect.

关 键 词：SIMULATION snow albedo snow melt spectral composition solar radiation 

分 类 号：P422[天文地球—大气科学及气象学]