CBERS-1CCD相机飞行绝对辐射标定试验地面同步测量与场地辐射特性分析

中国对地观测遥感卫星辐射校正场(即敦煌场)位于中国敦煌市西戈壁沙漠的西北角。整个敦煌场地面比较均匀、平坦,面积为30×40km²;测试区(标定区)面积为400×400m²,位于场区的中心位置。2000年8月底至9月初,中国资源卫星应用中心联合安徽光机所在敦煌场地进行了一次CBERS-1CCD传感器飞行绝对辐射标定试验。地表反射率和大气光学特性地面同步测量结果显示:敦煌场地的地面均匀性好,各个通道反射率的变化系数(即相对变化百分比)均小于3%。在可见光、近红外光谱范围内,地面光谱反射率随波长增加逐步增大,例如,在485nm波长处的地面反射率值约为0.18,在830nm波长处的反射率值约为0.26。大气光学特性测量结果显示:0.55μm波长处的大气总光学厚度(≈0.34)和气溶胶光学厚度(≈0.26)相对较小,大气水汽含量也较小。

Ground Simultaneous Measurements and Analysis of Radiometric Characterization of Dunhuang Test Site for Calibrating CBERS-1 Sensors

The Dunhuang test site is situated in the northwest corner of the Gobi desert near the city of Dunhuang. The calibration area is (400×400)m ² and situated in the centre of a relative homogeneous and flat zone of (30×40)km ². During August to September, 2000, China Center for Resources Satellite Data and Application (CRESDA) conducted a field measurement campaign for determining the characteristics of the ground reflectance and of the atmosphere. The results show that the test site has a very good homogeneity with a variation coefficient of the reflectance in any channel lower than 3%. The ground reflectance increases progressively from 0.18 at 485 nm to 0.26 at 830 nm. Atmospheric measurements show that at 0.55 μm the total atmospheric optical depth (about 0.34) and the aerosol optical depth (about 0.26) are relatively low and the effect of atmospheric water vapour content is also relatively small. These preliminary results show that the selected test site is well adapted to the absolute radiometric calibiration of in-flight satellite sensors such as CBERS-1 CCD.