SSM I DERIVED SNOW WATER EQUIVALENT DATA - THE POTENTIAL FOR INVESTIGATING LINKAGES BETWEEN SNOW COVER AND ATMOSPHERIC CIRCULATION/

Relationships between snow cover and atmospheric dynamics are difficul t To isolate because of the complex nature of their interaction. While regional snow lover patterns can be altered radically by a single cyc lonic event, the presence or absence of terrestrial snow covet can als o greatly influence passing weather systems. A consistent time series of snow cover data, coveting an extensive spatial area, at a synoptica lly sensitive temporal resolution is therefore required to examine pot ential relationships between surface snow conditions and atmospheric v ariables. Snow water Equivalent (SWE) derived from Special Sensor Micr owave/Imager (SSM/I) passive microwave data fits these requirements be cause of all weather imaging capabilities, broad spatial resolution, w ide swath width, and frequent revisit time. The applicability of these data to examining relationships between snow cover and atmospheric dy namics is evaluated in this paper through a comparative study of two w inter seasons currently available in rite appropriate grid format: Dec ember, January and February (DJF) 1988/89 and 1989/90. Five-day averag e (pentad) SWE imagery derived from SSM/I brightness temperatures usin g the Atmospheric Environment Service's (AES) dual channel algorithm i s analyzed along with gridded National Meteorological Center (NMC, now National Center for Environmental Prediction, NCEP) atmospheric data. Principal components analysis is used to isolate within variable reln tionships, while time lagged cross correlation analysis is used to ide ntify between variable relationships. Results indicate that both these data and the methodology show great potential for developing an SWE/a tmospheric climatology, although integration of a wet snow indicator, also developed by AES, would strengthen the snow cover product. Furthe r discussion regarding the future use of SSM/I derived SWE data for st udying snow cover/atmospheric interaction is also presented.