MODIS SNOW COVER VALIDATION FOR BHAGIRATHI RIVER BASIN IN NW HIMALAYA

摘要

The spatial and temporal distribution of snow cover area is a fundamental input to the atmospheric, hydrologic and climatic models. Herein MODIS/Terra snow cover product has been analyzed and validated for Bhagirathi river basin in NW Himalayan region. In the Bhagirathi basin there is only one observatory, hence, MODIS MOD10A2 snow cover maps are validated with the help of higher resolution LISS III image. LISS III image of June 11, 2004 having spatial resolution 23.5 m has been selected and compared with MOD10A2 product which has been derived from the MODIS images acquired from 9th June to 16th June 2004. GIS has been used to facilitate comparisons between MODIS and LISS-III snow maps. Both the images have been re-projected and resampled over the Bhagirathi catchment area. Initially the LISS III image has been classified into six categories namely rock, moraine, ice, lake, snow and cloud. The same has been rechecked with visual observation and limited field data. The same image has been reclassified into three categories as snow, land and cloud cover so as to have the same classification as in MOD10A2 products. From this, an error analysis of MOD10A2 product has been done by assuming that LISS III is the benchmark as it has a 23.5 km spatial resolution. MODIS misclassifies 3.34% land as snow and 4.63% of the bare land as snow. The accuracy of bare land classification is 87.25%, where as that of snow is 94.75%, and overall agreement is 92.03%.