FIELD OBSERVATIONS AND MODEL-CALCULATIONS OF DIELECTRIC-PROPERTIES OFARCTIC SEA-ICE IN THE MICROWAVE C-BAND

The complex dielectric constant of first-year and multiyear sea ice wa s measured during the Seasonal Ice Monitoring and Modeling (SIMMS) fie ld experiments, conducted in the Arctic in the spring of 1992, 1993, a nd 1995. The dielectric constant was also computed based on an establi shed dielectric mixing model by using different assumptions about incl usion shape. Computations were based on detailed measurements and obse rvations of ice physical properties and crystalline structure. Compari son between measurements and model results was conducted to identify w orking models for first-year and multiyear ice, For first-year ice, mo dels that employ the assumption of vertically oriented brine pockets a re applicable to columnar ice and those with the-assumption of randoml y oriented brine pockets are applicable to frazil ice, The validity of the models are established only for ice temperatures less than -8 deg rees C, For multiyear ice, there is no need to account for air bubble shape, The coexistence of brine and air inclusions in multiyear pond i ce makes it characteristically different from hummock ice, Best result s for pond ice were obtained from a simple model that accounts only fo r volume fractions of inclusions, rather than their shape. Physical pa rameters that can be retrieved directly from the dielectric constant a re salinity of first-year ice at temperatures below -15 degrees C and density of multiyear hummock ice. Detailed measurements of permittivit y and loss of first-year and multiyear ice are presented along with so me insight into interactions between the dielectric constant and physi cal parameters.