Sensitivity Analysis of Spectral Band Adjustment Factors For GF-1/WFV Sensor Cross-Calibration

Affected by the components aging and the space environment changing, the radiation performance of the first satellite GaoFen series (GF-1) changes since it has been launched. The orbit calibration can track the performance changing during the sensor's lifetime. Cross calibration using the high radiometric calibration precision can improve the calibration frequency and accuracy. Spectral band adjustment factors (SBAF) are important factors in cross calibration. Terra/MODIS is selected as reference sensor, GF-1/WFV as target sensor, and the SBAF can be calculated based on the in situ measurement spectral data at Dunhuang radiometric calibration site, considering the observation angle, spectral response, atmospheric conditions and surface properties. Time series cross calibration coefficients can be obtained according to the SBAF. GF-1/WFV apparent radiances are obtained by the cross calibration coefficients, while Terra/MODIS apparent radiances are obtained by the digital number and calibration coefficients. The relative deviations of apparent radiances between the two sensor's are compared by analysis. It shows that SBAF in different bands has same trends; The SBAF above 0. 9 are 53. 1%, 75%, 81. 2%, 93. 8% for blue, green, red, near-infrared bands, respectively; Time series calibration coefficients and SBAF are negatively correlated and the relative deviations of apparent radiances are smaller while the SBAF are closer to 1.