1. Parametric exponentially correlated surface emission model for L-band passive microwave soil moisture retrieval.
- Author
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Zhao, Tianjie, Shi, Jiancheng, Bindlish, Rajat, Jackson, Thomas, Cosh, Michael, Jiang, Lingmei, Zhang, Zhongjun, and Lan, Huimin
- Subjects
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SURFACE roughness , *SOIL moisture , *MICROWAVE radiometers , *SEAWATER salinity , *PARAMETERIZATION , *QUADRATIC equations , *STANDARD deviations - Abstract
Surface soil moisture is an important parameter in hydrology and climate investigations. Current and future satellite missions with L-band passive microwave radiometers can provide valuable information for monitoring the global soil moisture. A factor that can play a significant role in the modeling and inversion of microwave emission from land surfaces is the surface roughness. In this study, an L-band parametric emission model for exponentially correlated surfaces was developed and implemented in a soil moisture retrieval algorithm. The approach was based on the parameterization of an effective roughness parameter of H p in relation with the geometric roughness variables (root mean square height s and correlation length l ) and incidence angle. The parameterization was developed based on a large set of simulations using an analytical approach incorporated in the advanced integral equation model (AIEM) over a wide range of geophysical properties. It was found that the effective roughness parameter decreases as surface roughness increases, but increases as incidence angle increases. In contrast to previous research, H p was found to be expressed as a function of a defined slope parameter m = s 2 / l , and coefficients of the function could be well described by a quadratic equation. The parametric model was then tested with L-band satellite data in soil moisture retrieval algorithm over the Little Washita watershed, which resulted in an unbiased root mean square error of about 0.03 m 3 /m 3 and 0.04 m 3 /m 3 for ascending and descending orbits, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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