利用敦煌辐射校正场对FY-2B静止气象卫星进行可见光通道的在轨辐射定标
RADIOMETRIC CALIBRATION ON ORBIT FOR FY-2B METEOROLOGICAL SATELLITE' S VISIBLE CHANNELS WITH THE RADIOMETRIC CALIBRATION SITE OF DUNHUANG
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摘要: FY-2B由于杂散光的影响,其可见光通道的发射前定标存在较大误差。利用敦煌戈壁滩辐射校正场可进行FY-2B可见光通道的在轨绝对定标。由于FY-2B对于敦煌场区的卫星天顶角接近50°,需要进行场地的方向特性BRDF修正。2002年7月对FY-2B进行了场地地表反射率、大气消光、探空等项同步测量,并对场地的方向特性进行了测量。资料处理结果表明,FY-2B可见光通道杂散光可影响定标精度达20%。长期监视表明FY-2B可见光通道探测器输出十分稳定。该文将4个可见光通道探测器场地定标得出的定标查找表列出,供用户参考使用。Abstract: Pre-launch calibration of the FY-2B's visible channels has much error due to the influence of stray light. The radiometric calibration on orbit for FY-2B's visible channels might be running with the radiometric calibration site of Dunhuang's Gobi. There are must calibrated the BRDF of bi-direction characteristic of Dunhuang's site, because the zenith is close to 50°. The reflectance of the Gobi, light extinction of atmosphere and radiosonde observation were measured in synchronization for FY-2B in July 2002, while the bi-direction characteristics of the site were measured. The data processed results indicate that the calibration precision are debased 20% due to influence of stray light for FY-2B's visible channels, and the output of FY-2B's visible channels is very stabilization after long stakeout. The calibration tables calibrated by the site of four visible channels were listed.
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Key words:
- FY-2B;
- Stray light;
- Radiometric calibration on orbit;
- Visible channel;
- BRDF;
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表 1 FY-2B可见光通道主放大器放大倍数及14级增益系数
表 2 FY-2B扫描时刻大气参数
表 3 2002年7月18日定标查找表 (计数值与对应的各通道反射率)
表 4 可见-近红外通道场地定标误差分布
表 5 2002年7月18、20日定标查找表
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