Multiple resolution analysis of L-band brightness temperature for soil moisture

Passive microwave Earth observing systems provide coarse resolution data. Heterogeneity in physical characteristics will typically be present within footprints, especially over land. How this affects the development and validation of methods of retrieving soil moisture has not been verified. In this study, aircraft-based 1.4 GHz microwave radiometer data were collected sit several altitudes over test sites where soil moisture was measured concurrently. The use of multiple flightlines at lower altitudes allowed the direct comparison of different spatial resolutions using independent samples over the same ground location. Results showed that the brightness temperature data from 1.4 GHz sensor in this study region provides the same mean values for an area regardless of the spatial resolution of the original data. The relationship between brightness temperature and soil moisture was similar at different resolutions. These results suggest that soil moisture retrieval methods developed using high resolution data can be extrapolated to satellite scales.