Fig. 1. Comparison of two cloud droplet spectral distributions n(r). (a) Log-normal spectral distribution of MODIS inversion algorithm; (b) modified Gamma spectral distribution of WRF NSSL-2mom parameterization scheme

Fig. 2. Spectral response function F_s(λ) of 2nd and 5th channels of FY4A/AGRI. (a) Spectral response function of 2nd channel, with wavelength range of 0.55--0.75 μm; (b) spectral response function of 5th channel, with wavelength range of 1.58--1.64 μm

Fig. 3. Comparison of phase functions of response function integral computed based on response functions of 2nd and 5th channels of FY-4A/AGRI. (a) Phase function of visible band calculated under assumption of log-normal spectral distribution; (b) phase function of short-wave near-infrared band under assumption of log-normal spectral distribution; (c) phase function of visible band under assumption of modified Gamma spectral distribution; (d) phase function of short-wave near-infrared band under assumption of modified Gamma spectral distribution; (e) difference of phase function of visible channel under two spectral distribution assumptions; (f) difference of phase function of short-wave near-infrared channel under two spectral distribution assumptions

Fig. 4. Comparison of single scattering albedo with respect to integral of response function computed based on response functions of 2nd and 5th channels of FY-4A/AGRI. (a) Single scattering albedo in visible band; (b) single scattering albedo in short-wave near-infrared band

Fig. 5. Variation of reflectance with τ_COT and r_eff for 2nd channel (0.55--0.75 μm) and 5th channel (1.58--1.64 μm) of FY-4A/AGRI. (a) Calculated reflectance of visible band under assumption of log-normal spectral distribution; (b) calculated reflectance of short-wave near-infrared band under assumption of log-normal spectral distribution; (c) calculated reflectance of visible band under assumption of modified Gamma spectral distribution; (d) calculated reflectance of short-wave near-infrared band under assumption of modified Gamma spectral distribution; (e) reflectance difference of visible channel under two spectral distribution assumptions; (f) reflectivity difference of short-wave near-infrared channel under two spectral distribution assumptions

Fig. 6. Bi-channel reflectance look-up table of FY-4A/AGRI for water cloud. (a) Surface albedo is 0.07, SZA is 5°, VZA is 5°, and AZ is 10°; (b) surface albedo is 0.07, SZA is 20°, VZA is 30°, and AZ is 60°; (c) surface albedo is 0.13, SZA is 20°, VZA is 30°, and AZ is 60°; (d) surface albedo is 0.19, SZA is 20°, VZA is 30°, and AZ is 60°

Fig. 7. Disk scans and geolocation of FY-4A/AGRI at 07:00—07:15 on 20 August, 2020. (a) Reflectance at 0.65 μm; (b) reflectance at 1.61 μm; (c) SZA; (d) solar azimuth angle; (e) VZA; (f) satellite azimuth angle

Fig. 8. Comparison of FY-4A/AGRI cloud property retrievals under two cloud droplet spectral distribution assumptions, and observation time of FY-4A/AGRI is 07:00—07:15 on 20 August, 2020. (a) r_eff retrieved under assumption of log-normal spectral distribution; (b) r_eff retrieved under assumption of modified Gamma spectral distribution; (c) difference of retrieved r_eff under two spectral distribution assumptions; (d) τ_COT retrieved under assumption of log-normal spectral distribution; (e) τ_COT retrieved under assumption of modified Gamma spectral distribution; (f) difference of τ_COT retrieved under two spectral distribution assumptions

Fig. 9. Probability density distributions of FY-4A/AGRI cloud property retrievals under two spectral distributions. (a) Probability density distribution of r_eff retrieved under assumption of log-normal spectral distribution; (b) probability density distribution of r_eff retrieved under assumption of modified Gamma spectral distribution; (c) probability density distribution of τ_COT retrieved under assumption of log-normal spectral distribution; (d) probability density distribution of τ_COT retrieved under assumption of modified Gamma spectral distribution