Satellite and ground passive microwave remote sensing studies of ice and snow on and near Lake Superior

The subject of Lake Superior snow and ice passive microwave remote sensing is addressed in a series of satellite image analyses and in situ ground truth studies. The motivation is crysopheric monitoring in the North American Great Lakes region for climatological and navigational-industrial applications. The satellite passive microwave studies of lake ice are believed to be the first of their kind.; The first study explores the utility of SSM/I (Special Sensor Microwave/Imager) as a Great Lakes ice monitoring tool. Lake Superior ice conditions on February 1 and 4, 1996 are examined using SSM/I, AVHRR (Advanced Very High Resolution Radiometer) and National Ice Center ice chart data. Results indicated that lake ice brightness temperature (T{dollar}rmsb{lcub}B{rcub}{dollar}) and emissivity are comparable to those of new and young sea ice. Digitally coregistered SSM/I and ice charts indicate that ice T{dollar}rmsb{lcub}B{rcub}{dollar} and emissivity (37 GHz hpol) increase with increasing ice thickness.; A second study investigates Lake Superior and Great Lakes ice cover using time series of SSM/I brightness temperature images, and air temperature and snow accumulation data for the Michigan Technological University weather station. Computer animated Great Lakes image time series with daily time steps reveal patterns of ice growth from shore to mid-lake, and patterns of ice decay with accumulation of wind driven floes in the downwind south and east shores, consistent with the region's dominantly northerly and westerly winds. Graphs of T{dollar}rmsb{lcub}B{rcub}{dollar} (37 and 85 GHz) depict the range of values.; Surface roughness is a controlling factor in microwave backscatter and emission. Topographic transects were surveyed across four commonly occurring nearshore ice facies at 0.2 cm vertical and 5.0 cm horizontal resolutions. The four ice facies rank in roughness as follows (RMS roughness (cm)/correlation length (cm) in parentheses): single large pressure ridge (30/125), series of small pressure ridges (16/110), consolidated shuga zone (8/70) and young ice cakes (5/145). Thin snow cover was widespread on the nearshore facies, a condition notable for its implications on ice cover thermal evolution and electromagnetic signatures.; The effect of topographically controlled solar insolation on snow properties and 37 GHz T{dollar}rmsb{lcub}B{rcub}{dollar} was investigated in the field. Snow grain size and T{dollar}rmsb{lcub}B{rcub}{dollar} were measured on the north and south facing slopes of a 10 m wide east-west trending gully. Differential timing of melting during the diurnal cycle was observed, producing a time lag in brightness temperature between north and south facing slopes. The two slopes were not distinguishable on the basis of grain size distribution. Approximately 49% of the sieved snow grains were larger in diameter than the 37 GHz free space wavelength (8.1 mm), suggesting that volume scattering was an important process in this relatively typical snow pack.; An appendix summarizes in situ snow apparent brightness temperature measurements and computer programs used these and related studies.