Construction and evaluation of 12.5-km grid NSCAT backscatter maps over Arctic sea ice

Based on a nearly linear relationship between Ku-band backscatter and its derivative with respect to incidence angle over Arctic ocean sea ice, maps of backscatter have been produced, using the NSIDC 12.5-km pixel polar stereographic projection grid. Both three-day and one-day maps are studied. The noise level on these maps, evaluated from the difference between successive maps, varies from 2 to 7%, increasing as backscatter level or number of measurements decrease. Spectral analysis indicates the resolution of these maps to be around 40 km, that of the 25-km pixel maps around 60 km. Comparison with RADARSAT Widescan mode scenes, north of Spitsbergen and around Novaya Zemlya, confirm estimations of ice edge and help in interpretation of the maps, while indicating limitations of the water/ice discrimination algorithm.