Unformatted text preview: Temporal Changes in Snowcover on the Tibetan Plateau
Elizabeth Sanger Shithi Kamal Spring 2005, ESM 236 Objectives To characterize changes in snowcover in the Himalayas and the Tibetan Plateau over season and annual timescales Methods MODIS Snow cover algorithm ENVI Region of interest, Band threshold, Spatial and Band masked statistics MODIS/Terra Snow Cover February 2000 Present 8Day temporal resolution 0.05Deg (~110km2) spatial resolution 12 bit radiometric sensitivity in 36 bands Theory High albedo Reflectivity depends Differential between snow and clouds Reflectance High in visible Decreases in the NIR Grain size/shape Impurity Liquid water content Depth Roughness Solar elevation angle Snowmap Alogorithm Normalized Difference Snow Index (NDSI) Snow Cloud Diff: 0.4 14.4 m NDSI = Band 4 - Band 6 Band 4 + Band 6 Snow Mapper Cell Values
0 1100 111 252 253 254 255 Snowfree land Percent snow in cell Night Antarctica Data not mapped Open water (ocean) Fill Cell Value Mask
0 1100 111 252 253 254 255 Snowfree land Percent snow in cell Night Antarctica Data not mapped Open water (ocean) Fill Spatial Mask March 2002Gaussian March 2002Density March vs July 100% Snow Covered Pixels
100,000 80,000 60,000 Count 40,000 2000 2002 2004 20,000 0 MAR APR MAY JUN JUL AUG The End ...
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- Spring '08
- Snow, Tibetan Plateau, land Percent snow, Snowcover