Influence analysis of gaseous absorption on "HY-1A" CZI data processing

Besides ozone, oxygen and water vapour should be considered for their absorptive effects on "HY-1A" CZI data processing. First gaseous transmittances under various conditions are computed and analyzed for the band settings of this sensor. Second, transmittances under six standard atmospheres are approximated as functions of zenith angle, the water vapour transmittance is approximated as a function of water vapour content and zenith angle, and the ozone transmittance is approximated as a function of ozone content and zenith angle. Finally, taking Rayleigh scattering as an example, the influence of ignoring gaseous absorption when calculating TOA reflectance is analyzed, and the effect of applying the presented transmittance approximations to gaseous absorption correction for Rayleigh scattering in "HY-1A" CZI data processing is evaluated.