Airborne retrievals of snow and ice surface emissivity at millimeter wavelengths

Passive microwave radiometers (24-157 GHz) have been down over Baltic sea i ce and snow sites in April 1995 and on March 15, 1997. Data from these inst ruments are analyzed with reference to ground measurements of snow and ice conditions, and emissivity spectra are presented for 12 classifications of surface type. A simple model based on dielectric permittivity can accuratel y represent the microwave spectra of sea ice, but cannot be extended to the behavior of dry snow above 100 GHz without the addition of an extra term t o represent volume scattering. The parameterization presented is intended t o provide a background for temperature and humidity retrievals from satelli te sounders, but the results will be of interest to the snow and ice remote -sensing communities.