This paper discusses a combined data set obtained in the Canadian Arctic which partially covers the variation with season of the microwave signatures of sea ice. Results draw together airborne collection periods which include: March 1979, April 1979, and June 1980. The data set consists of RC-10 aerial photograph;HH- andHV-polarized backscattering coefficients from a fanbeam scatterometer operating at 13.3 GHz over incidence angles extending from nadir to60deg; 19.4 GHz,H-polarized radiometer brightness temperatures at a fixed incidence angle of45deg; and overlappingX- andL-band SAR imagery. A precision radiation thermometer (PRT-5) was also included in the sensor complement in the 1980 missions. Accumulated statistics for each microwave measurement were determined by segmenting the time histories of the profiling sensors by (WMO) World Meteorological Organization sea-ice class and then recombining the information for each ice category. Eigenvector analysis was applied to specify the radiometer and scatterometer hyperspace boundaries of each sea-ice class and examine the classification utility of this microwave information.