光谱匹配因子对GF-1/WFV时间序列交叉定标的影响分析

在轨运行的传感器辐射性能由于受到元部件老化、外太空辐射等因素的影响,会发生变化,通过传感器在轨定标可以及时追踪传感器在轨运行期间的辐射性能变化。利用Terra/MODIS(Terre卫星中分辨率成像光谱仪)参考,GF-1/WFV(高分-1号卫星视场传感器)传感器为目标,基于敦煌校正场的实测地表光谱数据,在考虑两传感器成像时刻的不同观测角度、光谱响应、大气条件和地表特性的匹配贡献的基础上,获得交叉定标光谱匹配因子,进一步得出WFV自发射后的时间序列交叉定标系数。以此辐亮度定标系数得到的表观辐亮度值与MODIS表观辐亮度值进行比对,开展光谱匹配因子对GF-1/WFV定标系数的影响分析。分析认为:在不同波段,光谱匹配因子变化趋势总体一致,大于0.9的光谱匹配因子比重分别为53.1%,75%,81.2%和93.8%;辐亮度定标系数的时间序列变化趋势与光谱匹配因子的时间变化趋势呈现负相关;匹配因子越接近1,两传感器辐亮度值的相对偏差越小。

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 ac-curacy .Spectral band adjustment factors (SBAF) are important factors in cross calibration .Terra /MODIS is selected as refer-ence 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 cali-bration 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 devia-tions of apparent radiances are smaller while the SBAF are closer to 1 .