利用MODIS和ASAR资料估算青藏高原念青唐古拉山脉地区冰雪范围及厚度

利用可见光和微波卫星遥感资料分析了青藏高原念青唐古拉山脉地区冰雪范围和厚度的季节变化.结果表明:青藏高原念青唐古拉山脉地区冰雪范围的季节变化非常明显,2003年4月上旬、5月中旬、7月下旬和9月下旬的冰雪范围分别占选定研究区域的28.9%、69.9%、11.6%和14.7%.在选定的西布冰川区域,由微波遥感得到的冰雪厚度季节变化也非常明显,5月份厚度的数值最大,7月份最小.由于主动微波观测受地面高程、地形和夏季冰雪融化等因素的影响比较大,主动微波遥感在大面积估算冰雪厚度还有一定困难,有待将来作进一步的深入研究.

Extent and Depth of Snow Cover over the Nyainqêntanghla Range Derived from ASAR and MODIS Data

In this paper, the seasonal variations of extent and depth of snow cover over the Nyainq ntanglha Range are assessed using the remote sensing data. The seasonal variation of snow cover extent over the study range is estimated from Earth Observation System / MODerate-resolution Imaging Spectroradiometer EOS /MODIS data, which, however, can not derive out snow depth. With considerations of the microwave radiative transfer and interaction between microwave radiation and snow/soil, a retrieval algorithm of snow depth is developed for applying the ENVISAT/ ASAR data. The speckle noise in the ASAR data is reduced using a self-adjective Lee filter. The effects of the slope and aspect of mountain are also considered in the ASAR data calibration. As a result, the snow covers take about 28. 9%, 69.9%, 11.6% and 14. 7% of the interesting region in April, May, July and September 2003. The seasonal variation of the estimated snow depth is evident; The depth reaches a maximum in May and a minimum in July. It is necessary to mention that the complex mountain elevation and summer melting of snow surface largely impact the retrieved snow depth. Using the ASAR data to estimate snow depth still has a certain difficulty in a large-scale, therefore, a thorough study is necessary in the future.