Assessing the use of dual-polarization RADARSAT-2 ScanSAR imagery for operational sea ice monitoring

Given the risk that sea ice poses to marine navigation and offshore structures, government ice centres such as the Canadian Ice Service (CIS) operationally monitor sea ice conditions in support of marine activity. While traditional monitoring approaches use wide swath, single-polarization, co-polarized, C-band synthetic aperture radar (SAR), recent advances in SAR technology have made the acquisition of wide swath, dual-polarization data possible for sea ice observations. The objective of this study is to evaluate additional sea ice information provided by dual-polarization observations of sea ice. In this study dual-polarization HH/HV RADARSAT-2 ScanSAR data acquired over the Gulf of St. Lawrence in February and March of 2009 are compared to coincident field measurements of sea ice thickness and surface roughness acquired with a fix-mounted helicopter-borne electromagnetic system. GPS ice beacon data and georeferenced video stills were also collected to provide localised ice flow vectors and qualitative sea ice surface conditions respectively. These field data are used to validate the interpretation of sea ice extent, concentration and stage of development in ice charts produced by the CIS. Additionally, field measurements acquired over points of interest identified by the CIS are analysed to identify unknown sea ice features observed in the SAR imagery. Preliminary results indicate that the cross-polarized channel provides improved separation of sea ice and open water and improved separation between smooth and deformed ice; however, thin ice types are difficult to identify in this channel. It is therefore recommended that ice centres utilize dual-polarization imagery.