Estimating accuracy in optimal deconvolution of synthetic AMSR-E observations

Abstract

Optimal deconvolution (ODC) utilizes the footprint overlap in microwave observations to estimate the earth's brightness temperatures ( T B). This paper examines the accuracy of ODC-estimated T B compared with a standard averaging technique. Because brightness temperatures cannot be independently verified, we constructed synthetic True T B for accuracy assessment. We assigned T B at a high spatial resolution (1 km) grid and computed the True T B by spatial averaging of the assigned T B to a lower resolution earth grid (25 km), selected to match the resolution of products generated from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E). We used the sensor antenna response function along with the 1-km assigned T B to generate synthetic observations at AMSR-E footprint locations. These synthetic observations were subsequently deconvolved in the ODC technique to estimate T B at the lower resolution earth grid. The ODC-estimated T B and the simple grid cell averages of the synthetic observations were compared with the True T B allowing us to quantify the efficacy of each technique. In areas of high T B contrast (such as boundaries of water bodies), ODC performed significantly better than averaging. In other areas, ODC and averaging techniques produced similar results. A technique similar to ODC can be effective in delineating water bodies with significant clarity. That will allow microwave observations to be utilized near the shorelines, a trouble spot for the currently used averaging techniques.