Comparison of two water vapor retrieval algorithms for HJ1A hyperspectral imagery

HJ-1A is one member of the Environment and Disaster Monitoring Microsatellite Constellation, which carries a HyperSpectral Imager (HSI) with the spectral resolution about 5nm from 450nm to 950nm. Retrieving columnar water vapor content is essential to the quantitative applications of hypespectral imagery. The ideal best band (940nm) for water vapor retrieval has lower signal-to-noise(S/N) value. In this paper, we choose another weak water absorption band (820nm) to retrieval the columnar water vapor content. Two common water vapor retrieval algorithms, called the Continuum Interpolated Band Ratio (CIBR) and the Atmospheric Precorrected Differential Absorption (APDA), are implemented and compared with each other. Simulation results show that these two algorithms have less difference in the accuracy of water vapor retrieval because the weak water vapor absorption effect in 820nm The water vapor contents derived from HJ-1A HSI by CIBR algorithm are compared with MODIS products and a systematic error may exist in the radiometric calibration of HSI.