Multi-frequency microwave remote sensing of summer Arctic sea ice attributes as indicators of climate and biophysical processes

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In the last 30 years, summer Arctic sea ice extent has rapidly declined, leading to uncertainties regarding the fate of the Arctic marine environment and the coordination of Arctic stakeholders. There is now an entirely new Arctic ice pack dominated by thinner first-year ice (FYI) instead of thicker multiyear ice (MYI). The areal fraction of low albedo melt ponds on summer ice, termed pond fraction (PF), has increased due to fewer topographical controls on flooding extent over FYI compared to rough MYI. Several field studies point to the coupling of PF evolution to rates of shortwave radiation absorption, light transmittance, upper ocean warming, under-ice primary production, and atmosphere-ocean biogeochemical exchanges, including contaminants. Our understanding of local scale PF evolution and relationships with components of the Arctic marine environment is not matched at regional and greater scales. By extension, parameterizations of PF in large scale sea ice models, largely based on local scale observations of MYI, are inadequate for reliable regional and basin-wide forecasts of sea ice and climate conditions. At all scales the impact of intra-seasonal melting state variations on PF evolution and coupled processes are poorly understood. A robust means by which to monitor and assess the seasonal decay of summer ice and related biophysical processes is needed. The proliferation of synthetic aperture radar (SAR) missions, including current and pending missions operating in constellation mode, will significantly enhance our ability to monitor the summer Arctic marine environment. Frequent, daily or better, regional scale observations regardless of cloud cover and weather conditions will contribute to monitoring and modeling studies within several interdisciplinary realms. This Discovery Grant will support a research program dedicated to the regional scale study of the summer Arctic ice-covered marine environment. Near term objectives will focus on understanding spatiotemporal characteristics of PF and ice melting state on FYI and MYI, their controlling mechanisms, and relationships to SAR imaging characteristics (frequency, polarization, and viewing angle). Research outcomes include the development of a robust, satellite earth observation based, framework for new and hind-cast studies of summer Arctic ice PF and melting state, as well as coupled biophysical processes. Contributions also include improvements to sea ice-climate model parameterizations, and enhancements to our ability to utilize SAR imagery from Canada's Radarsat-2 and pending Radarsat Constellation Mission to track and study sea ice during the fast changing summer melting period.