该文利用6S辐射传输模型设计了一种可对MAIS成象光谱仪进行飞行定标和反射率反演的方法,并分析了成象光谱图象反射率反演过程中影响反演精度的各种因素。这种方法的特点是地面同步测量中只采用一台仪器,同时获得了参考地物的反射率、大气光学厚度和大气垂直柱水汽含量。对1995年秋在内蒙古半干旱地区进行的一次MAIS成象光谱仪航空遥感飞行所获取的图象,利用GER MARK-V光谱辐射计对试验区内地面参考目标反射率和大气光学参量的同步测量数据进行了处理,结果表明,在可见光、近红外波段(0.4-1.2μm),MAIS传感器的辐射定标精度为8%,反射率反演精度为9.6%;在短波近红外波段(1.2—2.5μm),由于大气影响较小,MAIS传感器的辐射定标和反射率反演精度好于可见光、近红外波段。

In-flight experiment of MAIS imaging spectrometer and ground-based measurements using GER MARK-V spectroradio-meter simultaneously with the MAIS overpass were performed during Autumn 1995 at the semiarid area of Inner Monogolia, China. Based on these measurement data and MAIS image data, we designed a method for the radiometric calibration of MAIS sensor and an algorithm for reflectance retrieval from its image using 6S code, and discussed the influences of some factors in the retrieval procedure of surface reflectance. The distinguishing feature of this method is that obtaining simultaneously the surface reflectances of the reference target, atmospheric optical depth and water vapor abundance from the measurement data by only one instrument. The results show that the accuracy of MAIS radiometric calibration is about 8% and the estimated accuracy of the retrieved surface reflectance is about 9.6% in the visible and the near infrared wavelengths (0.4—1.2μm), i. e., the nearnadir surface reflectance factor is to within about 0.01—0.05 reflectance unit at the reflectance between 3% and 50%. The analysis indicates that the method presented here is suitable to the quantitative analysis of imaging spectral data in China.