Melt ponds on sea ice in the Canadian Archipelago 2. On the use of RADARSAT-1 synthetic aperture radar for geophysical inversion

Microwave scattering from a first-year sea ice (FYI) melt ponded surface is examined using RADARSAT-1 synthetic aperture radar (SAR) data collected du ring the 1997 Collaborative-Interdisciplinary Cryospheric Experiment (C-ICE '97) near Resolute Bay, Nunavut. This paper (1) investigates the utility of time series of microwave scattering to detect melt pond formation and (2) investigates approaches toward geophysically inverting information on the p hysical and radiative properties of this surface. We found melt pond format ion to coincide with a sharp rise in the temporal evolution of the microwav e scattering coefficient (sigma(degrees)) over FYI. RADARSAT-1 incidence an gle and surface wind speed explained > 90% of the variation in sigma(degree s). RADARSAT-1 sigma(degrees) was sensitive (R-2 = 0.80) to the fractional coverage of melt ponds during windy conditions (similar to 5.3 m s(-1)). Sp atial and temporal coincident measurements of RADARSAT-1 sigma(degrees) and the integrated shortwave albedo revealed a strong negative statistical cor relation (R-2 = 0.91) during windy conditions (similar to 5.3 m s(-1)). A w eaker, but strong, negative relationship (R-2 = 0.78) was observed for less windy conditions (similar to 3.2 m s(-1)), and a very weak positive relati onship (R-2 = 0.19) was found for low wind speed conditions (similar to 1.5 m s(-1)). All relationships were observed for melt pond fractions between 13 and 34%.