Publications

Ringerud, Sarah; Kummerow, Christian; Peters-Lidard, Christa; Tian, Yudong; Harrison, Kenneth (2014). A Comparison of Microwave Window Channel Retrieved and Forward-Modeled Emissivities Over the US Southern Great Plains. IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, 52(5), 2395-2412.

Abstract
An accurate understanding of land surface emissivity in terms of associated surface properties is necessary for improved passive microwave remote sensing of the atmosphere, including water vapor, clouds, and precipitation, over land. In an effort to advance this understanding, emissivities are calculated for a 5 degrees latitude by 5 degrees longitude region in the U. S. Southern Great Plains using a combination of land surface model and physical emissivity model. Results are compared to retrieved values from the Advanced Microwave Scanning Radiometer-Earth Observing System passive microwave observations for cloud-free scenes over a six-year period. The resulting emissivities are compared in the context of surface properties including surface temperature, leaf area index (LAI), soil moisture, and precipitation. The comparison confirms that lower frequency channels respond most directly to the surface soil and its dielectric properties. Differences between retrieved and modeled emissivities are generally lower than 2%-3% and appear to be a function of soil moisture and LAI at frequencies less than 37 GHz. Agreement is better for the vertical polarization channels. At 89 GHz, a large difference is present between retrieved and modeled emissivities in both mean and magnitude of variability, particularly in the summer months. Problems are likely present at higher microwave frequencies in both the retrieved and modeled products, including the inability of the emissivity model to represent liquid water in the form of dew or precipitation interception on the vegetation canopy.

DOI:
10.1109/TGRS.2013.2260759

ISSN:
0196-2892; 1558-0644