青藏高原边缘积雪辐射特征

Characteristics of the Radiation on Snow Cover at the Margin of the Tibet Plateau

利用中国陆地生态系统通量观测研究网络的玛曲站观测的一次降雪过程的资料,对青藏高原东部边缘冬季的降雪、积雪过程的辐射特征进行了分析.研究结果表明;积雪期晴天和降雪过程的向上短波辐射的峰值分别约为降雪前晴天的3和2倍.无积雪晴天地表反射率主要分布在0.175～0.36,新雪地表反射率主要分布在0.8～0.9.大气逆辐射变化较小,降雪过程的最大,积雪时的最小.地表长波辐射则为降雪前最大,降雪时最小.积雪覆盖的晴天比无积雪时的净辐射变化幅度减小,且早上由负转正的时间推迟.

Characteristics of radiation at a snowfall process and over snow cover in the margin of Tibet Plateau in winter were analyzed. The analysis was made by using the data of one snowfall process observed at Maqu station, which belongs to ChinaFlux Net. Results showed： upward shortwave radiation at the snowfall process and over snow cover is respectively double and triple as that without snow. Surface albedo varies mainly between 0. 175 and 0. 36 in a fine day without snow, and between 0.8 and 0.9 over new snow. The downward long wave radiation varies less. It is the maximum at the snowfall process and the minimum over the snow cover. Upward longwave radiation is the maximum before a snowfall and the minimum at the snowfall process. The net radiation over snow in a fine day varies less than that without snow cover, and the turning time for net radiation from negative to positive over snow cover delays in the morning.