|Laymon, Charles - GLOBAL HYDROL & CLIM CTR|
|Manu, Andrew - ALABAMA A&M UNIV|
|Crosson, William - GLOBAL HYDROL & CLIM CTR|
Submitted to: International Geoscience and Remote Sensing Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 19, 2000
Publication Date: N/A
Technical Abstract: The sensitivity of a passive microwave soil moisture retrieval algorithm to errors in the estimation of input variables and parameters was evaluated. By running the model while varying one parameter at a time, the effects individual parameters have on soil moisture retrieval were quantified. While most parameters result in soil moisture differences of less than about 4% volumetric water content (vwc), variations in the estimates of vegetation water content, vegetation b parameter, percent clay, and surface roughness result in the greatest differences in calculated soil moisture. The effects of these parameter variations on calculated soil moisture are greater at higher soil moisture levels and can result in differences in soil moisture retrieval up to 24% vwc. These same parameters have a compounded effect on calculated soil moisture when they vary collectively. When random errors are imposed on the Southern Great Plains 1997 Hydrology Experiment (SGP97) data set, the macrostructure of the soil moisture distribution remains intact, but the moisture field was significantly more heterogeneous. In addition to a compounding effect, random errors also have a compensating effect on calculated soil moisture, which reduces the overall negative impact. For SGP97 data, it is demonstrated that the overall error (2 sigma) in soil moisture calculated for any given brightness temperature may not be more than about 2.5 percent. This value would be higher for wet soils.