Recently, Peters-Lidard and coworkers published an analysis of modeled and measured soil moisture during the Washita '92 and '94 field campaigns suggesting that the spatial scaling of soil moisture is controlled in wet periods by processes controlling infiltration (e.g., including rainfall pattern, soil and vegetation properties) and in dry periods by processes controlling drainage and evaporation (e.g., soils, topography and vegetation properties). We will present recent work that further explores these issues in the context of the month-long Southern Great Plains '97 hydrology experiment (SGP97), during which daily soil moisture images at 800 m resolution were derived from brightness temperature measurements obtained with the airborne L band ESTAR microwave radiometer. This set of images, which compared favorably with in-situ volumetric soil moisture measurements, forms the basis of this study, along with the NOAH land surface model (developed by NOAA/NCEP, Oregon State University, the Air Force Weather Agency, and the Office of Hydrology). In this study, the NOAH model is applied with and without enhancements representing topography for comparisons to the spatial pattern of ESTAR-derived soil moisture estimates over the 11,000 square kilometer SGP97 test region. Results for both wet and dry periods will be presented and discussed in the context of the controlling processes described above.