Measuring the thermodynamic state of sea ice using synthetic aperture radar (SAR) time series data

Abstract

The study of atmosphere-sea ice-ocean processes using synthetic aperture radar (SAR) endeavors to improve estimates of energy flows and climate state variables from seasonally dynamic Arctic sea ice. This paper works toward this goal by characterizing the seasonal coevolution of the thermodynamic, electrical, brine volume, mechanical and microwave scattering characteristics of a snow covered landfast first-year (FY) sea ice volume for the purpose of investigating the theoretical framework which links them. The feasibility for using the time series evolution of the microwave scattering coefficient (/spl sigma//sup 0/) from SAR as a proxy indicator of the thermodynamic nature of FY sea ice over this seasonal transition is then assessed. Results indicate that SAR may hold utility in explaining microwave scattering over smooth FY sea ice types. FY sea ice surface temperature was found to explain between 69 and 84% of the seasonal variation in microwave backscatter from ERS-1 SAR during 3 consecutive winter to summer transitions (1993, 1994, 1995) at field locations near Resolute Bay, NWT. A discussion of the seasonal coevolution amongst the aforementioned components highlights the 'temperature-brine' relationship as instrumental in the development of a 'thermodynamic-scattering' link for landfast FY sea ice.