Characteristics of Arctic winter sea ice from satellite multispectral microwave observations

A coplanarity test using three scanning multichannel microwave radiometer channels shows the potential as well as the limitation of the sensor in discriminating different ice types. However, the capability for accurate determination of sea ice concentration, especially in the central Arctic, is evident from scatter plots of the emissivities using the two polarizations at 37 GHz. The consolidated ice data in the central Arctic form a very compact and linear set of points in these plots, and they slope the same way throughout the winter of 1979 and in other years (1980-1984). An ice concentration algorithm based on the utilization of this slope (about 1.03) is developed that yields retrieved values with an accuracy of about 5 percent in the central Arctic and 10 percent in the seasonal sea ice region. The total areal ice extent and actual ice cover were also derived from ice concentration retrieved by using the algorithm, and the results from several years of midwinter data show a relatively stable ice cover in the northern hemisphere.