Both theory and experiment in passive microwave remote sensing of snow have been studied. Synchronizing the airborne experiments using Microwave Scanning Radiometer (MSR) with the passing days of Marine Observation Satellite 1 (MOS-1), ground truth data were obtained around Asahikawa of Hokkaido during February 1988. Snow surface temperature, snow depth, and snow density were observed along the route of the aircraft from Mt. Asahidake to Biei. The distribution of snow water equivalent was identified and it was compared with brightness temperature derived from the airborne MSR. The microwave emission from snow at each observational site was calculated using the radiative transfer equation. Results of calculations considering Rayleigh scattering were in good agreement with the airborne observational data.