Consistency in long-term observations of oceans and ice from space

摘要: Satellite remote sensing has provided powerful tools for constructing long-term records of observations many Earth's geophysical processes. Geophysicists studying climage change would like to construct time series data which are as long, accurate, and consistent possible. While technological advances continue improve the quality from space, they also present consistency problems. The scanning multichannel microwave radiometer (SMMR), operated October 1978 August 1987, special sensor imager (SSMI), overlapped with SMMR nearly 2 months in have radiances been used monitor changes sea ice concentration snow accumulation, among other things. Inspection shown, however, that brightness temperatures two sensors over same polar firn-covered scene can differ by much 14 K. Calibration corrections firn derived; this paper, we calculations addressing physics small frequency viewing angle differences between SSMI on emission scenes containing free water. We focus here only surface emission. use a scattering model study effects roughness, wetness, density, young concentration. compare Antarctica our modeled results. find most scenes, roughness dominates differences, but open ocean series, must be calibrated constructed at product level rather than measured radiances.