ESTIMATION OF SNOW WATER EQUIVALENT USING PASSIVE MICROWAVE-RADIATIONDATA

A knowledge of the potential volume of water present in snowpacks is v ital for estimates of the global water balance. It is estimated that a bout three quarters of the world's terrestrial water reserves are lock ed in snow and ice. The principal objective of this study is to analyz e the degree to which passive microwave radiation can be used to inter pret snow water equivalent (SWE). The methodology reflects the importa nce of isolating phenomena other than SWE that may influence the micro wave signal. These factors include: snow wetness, depth hoar, complex mountainous terrain, and dense forest cover. Applying these four varia bles, 16 land-cover categories were identified, and relationships betw een SWE and brightness temperature were derived for each category. Res ults show that, for the ''simplest'' of these categories, a nonforeste d, 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. (C)Elsevier Science Inc., 1998.