The contribution of AMSR-E 18.7 and 10.7 GHz measurements to improved boreal forest snow water equivalent retrievals

Four seasons (2004-2007) of snow surveys across the boreal forest of northern Manitoba were utilized to determine relationships between vertically polarized Advanced Microwave Scanning Radiometer (AMSR-E) brightness temperatures (T-B) and ground measurements of snow water equivalent (SWE). Regression analysis identified moderate strength, yet statistically significant relationships between SWE and T-B differences (36.5-18.7; 36.5-10.7; 18.7-10.7) for individual seasons. When multiple seasons were considered collectively, however, the 36.5-18.7 and 36.5-10.7 differences were insignificant because the seasonal linear relationships shifted from year to year over the same T-B range regardless of SWE. This inter-seasonal consistency in T-B was explained through significant correlations with vegetation density as characterized by a MODIS-derived forest transmissivity dataset. More encouraging results were found for the 18.7-10.7 difference: the relationship with SWE remained statistically significant when multiple years were considered together, and the 18.7-10.7 difference was not significantly associated with vegetation density. Additional snow survey data from the Northwest Territories (2005-2007) were used to verify the 18.7-10.7 relationship with SWE across the northern boreal forest. These results suggest use of the 18.7-10.7 T-B difference, rather than the traditional 36.5-18.7 T-B difference, is necessary to capture inter-seasonal SWE variability across forested regions. Crown Copyright (C) 2008 Published by Elsevier Inc. All rights reserved.