ON THE LINKS BETWEEN MICROWAVE AND SOLAR WAVELENGTH INTERACTIONS WITHSNOW-COVERED 1ST-YEAR SEA-ICE

Electromagnetic (EM) energy at solar and microwavelengths will interac t with a snow-covered sea ice volume as a function of its geophysical properties. The seasonal metamorphosis of the snow cover modulates the relative distribution of the three main interaction mechanisms of EM energy: reflection, transmission, and absorption. We use a combination of modeling and observational data to illustrate how the total relati ve scattering cross section (sigma(o)) at microwavelengths can be used to estimate the surface climatological shortwave albedo and the trans mitted Photosynthetically Active Radiation (PAR) for a snow-covered, f irst-year sea ice volume typical of the Canadian Arctic. Modeling resu lts indicate that both 5.3 and 9.25 GHz frequencies, at HH polarizatio n and incidence angles of 20-degrees, 30-degrees, and 40-degrees can b e used to estimate the daily averaged integrated climatological albedo (alpha). The models at 5.3 GHz, HH polarization, at 20-degrees, 30-de grees, and 40-degrees incidence angles were equally precise in predict ions of alpha. The models at 9.25 GHz were slightly less precise, part icularly at the 40-degrees incidence angle. The reduction in precision at the 40-degrees incidence angle was attributed to the increased sen sitivity at both 5.3 and 9.25 GHz to the snow surface scattering term (sigma-degree(ss)) used in computation of the total relative scatterin g cross section (sigma-degree). Prediction of subsnow PAR was also pos sible using the same combination of microwave sensor variables utilize d in prediction of alpha, but because subice algal communities have ev olved to be low light sensitive, the majority of the growth cycle occu rs prior to significant changes in sigma-degree. A method of remote es timation of snow thickness is required to be scientifically useful. Ob servational data from the European ERS-1 SAR were used to confirm the appropriateness of the modeled relationships between sigma-degree, alp ha, and PAR. Over a time series spanning all conditions used in the mo deled relationships, the same general patterns were observed between s igma-degree, alpha, and PAR.