MICROWAVE SNOW SIGNATURES (1.5 MM TO 3 CM) OVER ALASKA

The intensity of microwave radiation emitted from snowpack is a function of the temperature, density, crystal size and free water content of the snow. The 37 GHz sensor on-board the Nimbus-7 SMMR is often used to retrieve snow information because scattering by snow crystals is a dominant factor at this frequency. The 92 GHz radiometer which is more sensitive to snow crystal scattering was on-board the NASA CV-990 airborne experimental laboratory during the Marginal Ice Zone Experiment (MIZEX) of 1983, which provided an opportunity to study the snow signatures over Alaska. A combination of passive microwave radiometers in the mm to cm region with higher spatial resolution will greatly improve remote snowpack parameter monitoring. In cloud-free areas, 92 GHz microwave brightness patterns over snow in Alaska were found to be similar to the microwave brightness patterns from the 37 GHz data.