Distinctive characteristics of glacial ice in the PR-GR scatter plots of AMSR-E NASA Team2 sea ice algorithm

Sea ice concentration (SIC) calculated from the AMSR-E by using NASA Team2 (NT2) algorithm has proven to be very accurate over sea ice in Antarctic Ocean. When glacial ice such as icebergs and ice shelves are dominant in an AMSR-E footprint, the accuracy of NT2 algorithm is not well maintained. We extracted the concentrations of sea ice and glacial ice from two ENVISAT ASAR images of southern Antarctica, and compared them with NT2 SIC. The result showed that the NT2 algorithm underestimates the concentration of glacial ice. We also found that glacial ice occupies a unique region in the PR (polarization ratio), GR (spectral gradient ratio), PRR (rotated PR), and ΔGR domain different from other types of ice such as ice type A, B, and C, and open water. This implies that glacial ice concentration can be added as a new category of ice to the NT2 algorithm.