Passive microwave detection of snowmelt and runoff

Snow melt provides the dominant hydrologic signal for many watersheds across the globe. In developing countries and very remote regions, snow data are rarely available and assessing a snowpack's volume of water can be especially difficult. Remotely sensed passive microwave data offer the capability to monitor snowpack and snowmelt runoff in regions of limited data. Abrupt transitions in the SSM/I and AMSR-E passive microwave SWE estimates can indicate when the dry snowpack becomes wet and signify the onset of melt or rain-on-snow events. These transitions were analyzed with available discharge data to determine the utility in hydrological predictions in a large watershed in central Afghanistan and one of similar size in the United States. A correlation was found between abrupt decreases in SWE and discharge increases following rain events. The value for flood flow predictions is discussed.