Fig. 1. Schematic diagram of FY-4B/GIIRS optical system

Fig. 2. Layouts of infrared plane array detector. (a) FY-4A/GIIRS; (b) FY-4B/GIIRS

Fig. 3. Spectral coverage range of geostationary satellite hyperspectral instrument

Fig. 4. FY-4B/GIIRS NEdR spectra calculated using CBB, HBB, and ICT data, respectively

Fig. 5. NEdRs of all FOVs in the two bands of FY-4B/GIIRS [subplot shows that the NEdR level of LWIR FOV-96 is higher than that of others (take FOV-56 as example)]

Fig. 6. Nonlinear raw spectrum of ICT in LWIR band (subplot shows nonlinear spectrum in low frequency range)

Fig. 7. Comparison of GIIRS spectral responsivity before and after nonlinearity correction. (a) FOV-56 spectral responsivity before nonlinearity correction; (b) FOV-56 spectral responsivity after nonlinearity correction

Fig. 8. Calibrated BT spectra, BT bias, and residual standard deviation of FOV-56 pixel after nonlinear correction. (a) Calibrated BT spectra; (b) BT bias; (c) residual standard deviation

Fig. 9. Calibrated BT spectra, BT bias, and residual standard deviation of FOV-56 pixel after nonlinear correction. (a) Calibrated BT spectra; (b) BT bias; (c) residual standard deviation

Fig. 10. Calibrated BT spectra, BT bias, and residual standard deviation of FOV-96 pixel after nonlinear correction. (a) Calibrated BT spectra; (b) BT bias; (c) residual standard deviation

Fig. 11. BT residual of all FOVs at T_HBB of 280 K

Fig. 12. BT differences of GIIRS observations at different T_HBB (take FOV-56 as example)

Fig. 13. HBB BT residual corresponding to GIIRS observation dynamic range