Publications

Han, XJ; Duan, SB; Li, ZL (2017). Atmospheric correction for retrieving ground brightness temperature at commonly-used passive microwave frequencies. OPTICS EXPRESS, 25(4).

Abstract
An analysis of the atmospheric impact on ground brightness temperature (T-g) is performed for numerous land surface types at commonly-used frequencies (i.e., 1.4 GHz, 6.93 GHz, 10.65 GHz, 18.7 GHz, 23.8 GHz, 36.5 GHz and 89.0 GHz). The results indicate that the atmosphere has a negligible impact on Tg at 1.4 GHz for land surfaces with emissivities greater than 0.7, at 6.93 GHz for land surfaces with emissivities greater than 0.8, and at 10.65 GHz for land surfaces with emissivities greater than 0.9 if a root mean square error (RMSE) less than 1 K is desired. To remove the atmospheric effect on T-g, a generalized atmospheric correction method is proposed by parameterizing the atmospheric transmittance tau and upwelling atmospheric brightness temperature T-ba up arrow. Better accuracies with T-g RMSEs less than 1 K are achieved at 1.4 GHz, 6.93 GHz, 10.65 GHz, 18.7 GHz and 36.5 GHz, and worse accuracies with RMSEs of 1.34 K and 4.35 K are obtained at 23.8 GHz and 89.0 GHz, respectively. Additionally, a simplified atmospheric correction method is developed when lacking sufficient input data to perform the generalized atmospheric correction method, and an emissivity-based atmospheric correction method is presented when the emissivity is known. Consequently, an appropriate atmospheric correction method can be selected based on the available data, frequency and required accuracy. Furthermore, this study provides a method to estimate tau and T-ba up arrow of different frequencies using the atmospheric parameters (total water vapor content in observation direction L-wv, total cloud liquid water content L-clw and mean temperature of cloud T-clw), which is important for simultaneously determining the land surface parameters using multi-frequency passive microwave satellite data. (C) 2017 Optical Society of America

DOI:
10.1364/OE.25.000A36

ISSN:
1094-4087