Integrating passive microwave remotely sensed imagery and gridded atmospheric data: A study of North American Prairie snow cover

Terrestrial snow cover is an important climatological variable because of its influence on the surface radiative balance, and a significant hydrological variable as it acts as the frozen storage term in the water balance. Satellite passive-microwave imagery has been used as a source of snow cover information because of all-weather imaging capabilities, rapid scene revisit time, and the ability to derive quantitative estimates of snow water equivalent (SWE).; In this study, ten winter seasons (December, January, February 1988/89 to 1997/98) of five day averaged (pentad) passive-microwave derived SWE imagery are utilized to examine the seasonal snow cover characteristics of a ground-validated North American Prairie study area.; Four dominant patterns are identified within the ΔSWE time series. The positive (negative) phase of PC1 captures a pattern of widespread SWE ablation (accumulation) in the south with accumulation (ablation) to the north. The positive (negative) phase of PC2 characterizes a meridional accumulation (ablation) zone oriented from the northwest to southeast of the study area. The positive (negative) phase of PC3 indicates a regional melt event (accumulation event) in the lee of the Rocky Mountains. Finally, the positive (negative) phase of PC4 characterizes increasing (decreasing) SWE in the vicinity of the Red River Valley.; National Center for Environmental Prediction (NCEP) gridded atmospheric data (500 mb geopotential height; 700 mb temperature) and model produced isentropic potential vorticity (IPV) fields are investigated in conjunction with the first four ΔSWE principal components to identify whether consistency exists in the atmospheric patterns associated, at no time lag, with these dominant ΔSWE modes. When a deep eastern Arctic low with an associated trough extends over the continental interior of North America, snow accumulation is the expected response (as characterized ΔSWE PC1 positive, PC2 positive, and PC4 positive). Regions of strong IPV are spatially associated with areas of increased SWE. When atmospheric ridging dominates North American circulation, snow ablation in the Prairies is the expected response, with ridge location controlling the Prairie region where ablation occurs (as characterized ΔSWE PC] negative, PC2 negative, and PC4 negative). Discontinuous, weak IPV regions typically located to the north and east of the study area are linked to the occurrence of decreased SWE. (Abstract shortened by UMI.)...