A SCATTERING MODEL FOR SNOW-COVERED SEA ICE

The special properties of a robust radiative transfer model for scattering from layers of inhomogeneous rough-boundary slabs are first presented: (1) The dense medium effect for a random distribution of spheres is incorporated by redefining the phase function in terms of electromagnetic field expressions without the far zone approximation; (2) boundary roughness is modeled using the Integral Equation Model (IEM) for random surfaces; and (3) multiple scattering and volume/boundary interactions are accounted for using the matrix doubling method. Then the model is applied to backscattering from saline and desalinated ice. Comparisons are made at single and multiple frequencies with some of the most complete (in terms of both backscatter measurements and ice physical characterization) sets of measurement data available, using measured physical and electrical characteristics of the ice as inputs to the model where possible. The results show close agreement. For example, for the saline ice backscatter data set, which consisted of measurements at two like and two cross polarizations at 5 and 13.9 GHz, the agreement with model predictions is within 2 dB except at 13.9-GHz cross polarization (see text for discussion). Backscattering from > 15 cm-thick saline ice is generally dominated by scattering from the top surface while backscattering from < 8 cm-thick saline ice can be strongly influenced by returns from the ice/water interface, particularly at frequencies less than about 5 GHz. Comparisons with measurements from desalinated ice also show good agreement.