Developing Snow Cover Parameters Maps from MODIS, AMSR-E, and Blended Snow Products

Snow cover onset date (SCOD), snow cover end date (SCED), and snow cover duration (SCD) are important parameters for providing comprehensive characteristics of regional or global snow cover conditions and are traditionally derived from in situ observations. In this study, we test three methods, two new (1 and 2) and one published (W_X), in deriving those parameters from remotely sensed snow cover maps, i.e., AMSR-E, MODIS multi-day combined (MODISMC8), and MODIS/AMSR-E blended. These image-derived parameters are evaluated against those from in situ measurements at 244 SNOTEL stations in the Pacific Northwest, during the 2006 to 2008 hydrological years. Results indicate that biases are mainly from scale difference between images and in situ observations and that the Method 2/MODISMC8 combination performs the best. Three SCD maps (one for each year) have very similar distribution patterns, although the SCOD and SCED maps vary from year to year and from area to area.