Fig. 1. Nonlinear response diagram

Fig. 2. Simulated spectral signal

Fig. 3. Simulated nonlinear data signal

Fig. 4. Measured spectral data (a) LW，(b) MW1，(c) mw2

Fig. 5. Black body temperature curve

Fig. 6. Nonlinear correction coefficient (a) LW: in-band correction method，(b) LW: out-of-band correction method，(c) MW1: in-band correction method，(d) MW1: out-of-band correction method;

Fig. 7. Average brightness temperature deviations of mediumwave 1 by uncorrected and in-band correction methods of different FOV (a) LW,(b)MW1

Fig. 8. Average brightness temperature deviations of mediumwave 1 by in-band and out-of-band correction methods of different FOV (a) LW，(b)MW1;

Fig. 9. Spectral responsivity comparison (a) longwave before correction，(b) longwave after correction，(c) mediumwave1 before correction，(d) mediumwave1 after correction

Fig. 10. Bright-temperature comparation of HIRAS-II and IASI (a) no nonlinear correction，(b) out-of-band correction，(c) in-band correction

Fig. 11. The geographic location of the cross-match points

Fig. 12. The average radiant brightness temperature bias of ground targets compared with IASI