Cooperative Institute for Research in Environmental Sciences

Science Rendezvous > 2009 Posters
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Snow Cover Mapping at the Continental to Global Scale Using Combined Visible and Passive Microwave Satellite Data

Armstrong, R. L., M. J. Brodzik, M. H. Savoie

Over the past several decades, both visible and passive microwave satellite data have been used for snow mapping at continental to global scales. Both passive microwave and visible data sets indicate a similar pattern of inter-annual variability (Figure 1), although the maximum snow extents derived from the microwave data are consistently less than those provided by the visible satellite data, and the visible data typically indicate higher monthly variability (Figure 2). We describe the advantages and disadvantages of these two types of satellite data for snow cover mapping. We include examples of two multi-sensor approaches to blend the information from both methods. For the period 1978 to present, we combine frequency of occurrence data from the NOAA weekly snow charts with average monthly snow water equivalent (SWE) derived from the SMMR and SSM/I brightness temperature data. For the period since 2000, we blend data from the NASA EOS MODIS with SSM/I.

This new product incorporates MODIS data from the Climate Modelers Grid (CMG) at approximately 5 km, with microwave-derived SWE at 25 km, resulting in a blended product that includes percent snow-covered area (SCA) in the 25 km grid cell and uses 85 GHz data to enhance accurate mapping of shallow and intermittent snow cover.