Assessing the impact of melt and refreeze on SSM/I derived North American Prairie snow water equivalent

The passive microwave time series provides ideal imagery for investigating terrestrial snow cover because of all-weather imaging, rapid scene revisit, and the ability to derive quantitative estimates of snow water equivalent (SWE). Metamorphism of snowpack structure, driven by melting and refreezing of the snowpack can, however, cause regional errors in the estimation of SWE by passive microwave technology. The purpose of this study is to assess the utility of surface air temperature data for isolating measurement intervals when passive microwave retrieved SWE is likely to be biased because of the physical state of the snowpack. Ten winter seasons (December, January, February 1988/89 through 1997/98) of air temperature data are filtered to identify a range of melt and refreeze conditions for a North American Prairie study area. Five day averaged (pentad) Special Sensor Microwave/Imager (SSM/I) derived SWE imagery are subsequently investigated to identify any systematic response in measured SWE