Analysis And Application Of Albedo And Snow Remote Sensing Products Over The Tibetan Plateau

Land surface albedo, is one of the most essential surface parameters because it can control surface radiation energy budget, and partition radiative energy between the atmosphere and land surface. Snow cover and glaciers, as the main components of the cryosphere, play extremely important role in the surface radiation energy budget, water vapor flux, river runoff, regional and global climate change. Snow and glacier albedo significantly influence the surface radiation energy budget and make feedback to global climate change. The Tibetan Plateau is one of the three main snow cover distribution centers in China. The lofty and rugged terrain of the TP significantly influences the atmospheric circulation and climate in China, the East Asian and even global, which make the TP become the most sensitive ecosystem to global climate change. Therefore, it’s critical for further investigation on the atmosphere-land interactions and ecosystem that achieve high quality albedo, monitor snow cover areas and study the relationship between snow cover and albedo.Although both GlobAlbedo and MODIS global albedo products can provide the high spatiotemporal resolution albedo over the TP, few studies have been conducted to assess the accuracy of GlobAlbedo products. At the same time, the accuracy of the MODIS snow products is intensively verified and its application is widely conducted in monitoring the snow cover variation, snow melting runoff simulation and so on. However, there are few studies on the assessments the accuracy and applications of the MODIS daily snow cover products. Thus, assessments on the accuracy of the GlobAlbedo products with ground measurements and MODIS albedo, evaluation of the MODIS snow products with ground measurements, monitoring the snow cover area, and study on the relationship between albedo and snow cover, are of significant value for monitoring the natural disasters and ecological environment over the TP and researching the global climate change.The main work of this paper includes:(1) The evaluation of the Glob Albedo products over the TP. Albedo ground measurements from seven sites over the TP were used to quantitatively analyze the accuracy of the GlobAlbedo product. GlobAlbedo was also compared with the MCD43B3 albedo product. Results show that when snow fraction is less than 0.1, the RMSE between GlobAlbedo and ground measurements is 0.0199 and that between MCD43B3 and ground measurements is 0.0259. No significant difference is observed between GlobAlbedo and MCD43B3. By contrast, when snow fraction is no less than 0.1, the accuracies of GlobAlbedo and MCD43B3 are barely satisfactory, although the RMSEs of GlobAlbedo are slightly better than those of MCD43B3. The RMSE between GlobAlbedo and ground measurements is 0.1045, whereas that between MCD43B3 and ground measurements is 0.1246. Moreover, the differences are analyzed between the GlobAlbedo and MCD43B3 albedo products in the spatiotemporal distribution over the TP.(2) The evaluation and application of the MODIS snow cover product over the TP. The accuracies of the MOD10A1 and MYD10A1 snow products are assessed with the snow depth ground measurements from sites. And the MOD10A1 snow product is compared with the MYD10A1. Moreover, this paper evaluated the new snow cover product, a combination of the MOD10A1 and MYD10A1, which can reduces the effect from the cloud. Finally, the snow cover variations are monitored with the new snow cover product spanning 2003 to 2014 over the TP.(3) The research on the relationship between the snow and albedo over the TP. With the above new snow product and the MODIS albedo product MCD43B3 from 2010 to 2014, the percentages are calculated and analyzed on the snow and snow-free pixels with the albedo no less than 0.4, as well as the snow pixels, snow-free pixels and no-decision pixels when the albedo is or no less than 0.4.