Nonlinear response correction method for on-orbit data of FY-3E hyperspectral infrared atmospheric sounder Ⅱ
The Infrared Hyperspectral Atmospheric Sounder Ⅱ(HIRAS-Ⅱ)mounted on Funyun-3E satellite(FY-3E)can realize vertical atmospheric detection,featuring hyper spectral,high sensitivity and high precision.When the satel-lite has been on-orbit,nonlinear response would occur due to instrument attenuation and environmental change,which affects the accuracy of on-orbit calibration.For nonlinear response problems,a nonlinear correction method based on in-band spectrum is proposed.Firstly,the nonlinear correction coefficient was solved based on the nonlinear characteris-tics of the out-of-band in low-frequency spectra,and the coefficient was input into the radiological calibration model as the initial value.The deviation between the black-body spectrum measured on board and the ideal spectrum was taken as the objective function,and the nonlinear correction coefficient was optimized by iterative calculation.Radiation calibra-tion experiments have shown that the brightness temperature deviation of black body is reduced compared to uncorrected result and the out-of-band correction method using the proposed method.Based on the simultaneous nadir overpass meth-od,After matching the observed data of HIRAS-Ⅱ with IASI and calculating the mean brightness temperature deviation and the absolute value of the deviation,the mean brightness temperature deviation after nonlinear correction by the in-band correction method is-0.13 K,which is better than the out-of-band correction method.
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