Estimation of Snow Water Equivalent Using Passive Microwave Radiation Data

Abstract

A knowledge of the potential volume of water present in snowpacks is vital for estimates of the global water balance. It is estimated that about three quarters of the world’s terrestrial water reserves are locked in snow and ice. The principal objective of this study is to analyze the degree to which passive microwave radiation can be used to interpret snow water equivalent (SWE). The methodology reflects the importance of isolating phenomena other than SWE that may influence the microwave signal. These factors include: snow wetness, depth hoar, complex mountainous terrain, and dense forest cover. Applying these four variables, 16 land-cover categories were identified, and relationships between SWE and brightness temperature were derived for each category. Results show that, for the “simplest” of these categories, a nonforested, nonmountainous terrain, with no depth hoar or melting snow, the SWE can be estimated with 95% confidence within ±44 mm. The confidence limits increase as the complexity of the snowpack, land form, and land cover increases.