Controlling factors analysis and improvement for the Himawari-8 aerosol optical depth accuracy from the standpoint of orientation information in China

Abstract:

This work aims at providing a novel controlling factors analysis for the Advanced Himawari Imager (AHI) aerosol optical depth (AOD) retrieval from the aspect of Sun-Earth-Satellite geometries, through combining the high quality ground-based observation in several cities of China. The four-year co-located AOD dataset of AHI and sun-photometer in the study areas are used to support this work. AHI overall underestimates AOD in China with coefficient of determination (R²) more than 0.65. Though the best retrieval appeared in summer, underestimation is found to be persistent in each season. The correlation and bias analyses of AOD with respect to the variation of solar zenith angle, relative azimuth angle and scattering angle in cities are respectively performed. The influence of satellite zenith angle is also discussed. Phase function derived by sun-photometer is applied to discuss the influence of scattering angle on AOD inversion. Accompany with the scattering angle, the AOD retrieval bias consistently varies with the phase function bias, which further confirm the impact of phase function on AHI retrieval. Finally, we take Wuhan as an example to improve the simulation of aerosol model through ground-based observation and get a better AOD retrieval from Himawari.