Analysis of visible and microwave satellite data for snow mapping in Alaska

Analysis of passive microwave Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSMI) data, in conjunction with Advanced Very High Resolution Radiometer (AVHRR), topographic data and vegetation maps has been undertaken for a period of time in 1989 in Alaska. The combined use of visible, near-infrared and microwave sensors to map snow will lead to an improved ability to map snow extent, albedo and water equivalent. Such data are available now from the AVHRR, and in the future, from the Earth Observing System Moderate Resolution Imaging Spectroradiometer (MODIS). Passive microwave sensors are necessary in order to augment visible and near-infrared sensors which cannot acquire data through cloud cover and darkness. Results show a strong dependence of the microwave brightness temperature on topography, and land cover. Also, the influence of persistent meteorological conditions on snow temperature is hypothesized as an explanation for a brightness-temperature anomaly observed during the winter in the northern foothills of the Brooks Range, Alaska.