Comparison of Helicopter-borne Measurements of Sea-Ice Properties with ENVISAT ASAR APP Data for Amundsen Gulf

Measurements of sea-ice properties were collected using helicopter-borne sensors in Amundsen Gulf, to assess the improved capabilities of ENVISAT dual-polarization advanced synthetic aperture radar (ASAR) data for monitoring sea ice type and sea ice topography. Sea ice thickness and surface roughness profiles were collected with an electromagnetic-laser system fix- mounted on the front of a helicopter, and video images were collected with a downward-looking video camera. Dual- polarization SAR data show some improved capability for classifying thin ice types, however atmospheric conditions need to be considered. Information on sea ice thickness is needed for safe and efficient navigation in ice-infested waters and for climate studies. Since the early 1990's, spaceborne synthetic aperture radar (SAR) data have been used operationally for sea ice monitoring by national ice agencies such as the Canadian Ice Service. Single-polarization SAR data available from ERS1/2 and RADARSAT have provided information on ice edge location, ice concentration, stage of development and floe size. With the launch of ENVISAT several years ago, dual- polarization advanced SAR (ASAR) data became available. In April-May 2004, a field survey of ice properties using helicopter-borne sensors was conducted in the southern Beaufort Sea. Observations were collected in part to assess the enhanced capabilities of ASAR data for sea ice monitoring, and in particular for providing information on sea ice type and sea ice topography. The observations can also be used in the development of improved algorithms for sea ice classification. During the survey, data were collected both in Amundsen Gulf as part of the Canadian Arctic Shelf Exchange Study (CASES), and to the west off the Mackenzie Delta in support of oil and gas development (Fig. 1). In this paper, ENVISAT ASAR images are compared with field observations from the Amundsen Gulf region.