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FY-1C CAVHRR归一化植被指数（NDVI）衰减订正方法研究
IMPROVED NDVI of FY-1C CAVHRR
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摘要: 利用FY-1C连续3年的CAVHRR资料，以敦煌辐射校正场为分析区，分析了CAVHRR可见光、近红外通道的通道衰减特征，开展了归一化植被指数（NDVI）衰减订正方法研究及衰减订正试验。分析结果表明，FY-1C可见光通道1的衰减使FY-1C全球及区域NDVI的分布特征出现不合理。以敦煌辐射校正场为参考目标，借助敦煌目标区通道反射率长时间变化特征分析，可以建立NDVI的时变订正模型，有效订正通道衰减引起的NDVI的不合理性。利用敦煌NDVI值稳定不变的特性得到的FY-1C扫描辐射计通道1更新定标系数，与2000年9月中国辐射校正场外定标试验结果一致。研究结果有助于提高FY-1C可见光、近红外通道遥感资料在环境遥感监测方面的定量应用精度。Abstract: An analysis of the NDVI and the calibration coefficients used to describe sensor degradation in Channel 1 of the Chinese Advanced Very High Resolution Radiometer (CAVHRR) boarding on the FY-1C spacecraft are presented. The radiometrically stable permanent sand of Dunhuang is used as a target to characterize sensor performance, and remote sensing data of CAVHRR over Dunhuang during 3 years was used. The analysis results show that the degradation in Channel 1 of FY-1C made the distribution of FY-1C NDVI all over the world fuzzy and cannot show the situation of canopy growing. Corrected model for NDVI and califuzzy and cannot show the situation of Channel 1 of FY-1C CAVHRR constructed from Dunhuang reflectivity and NDVI database can improve the FY-1C global NDVI distribution. The relationship improving with time for NDVI and calibration coefficients for Channel 1 of FY-1C was derived from this researching work. The improved new calibration coefficients for CAVHRR Channel 1 have a great correspondence with the results of CRCS is 2000. It is recommended that the derived model and coefficients are helpful to improve the quantity application of FY-1C global remote sensing data.
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Key words:
- Sensor degradation;
- NDVI;
- Improved calibration coefficients
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图 4 通道1衰减订正效果分析图
(下部一组曲线中的兰线为衰减订正前FY-1C通道1反射率测值的变化情况；辉县为以归一化植被指数为参照进行衰减订正后得到的通道反射率值；红线为根据订正定标系数重算得到的通道反射率测值。上部的黑线为订正后的归一化植被指数时变曲线)
表 1 FY-1C可见光、近红外通道光谱参数
表 2 A、B系数表
表 3 FY-1C通道1不同时段更新后的定标系数
表 4 2000年外定标结果与INDV衰减订正结果的对比分析
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[1] 谷松岩, 邱红, 刘玉洁, 等. FY-1C可见光通道衰减分析及订正试验.应用气象学报, 2002, 13(6):734-740. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20020696&flag=1 [2] Rao C R N, Chen J. Inter-satellite calibration linkage for the visible and near infrared channels of the Advanced Very High Resolution Radiometer on the NOAA-7, 9, and 11 spacecraft. Int. J. Remote Sensing, 1995, 16: 1931-1942. doi: 10.1080/01431169508954530 [3] Rao C R N, Chen J. Post-launch calibration of the visible and near infrared channels of the Advanced Very High Resolution Radiometer on the NOAA-14 spacecraft. Int. J. Remote Sensing. 1996, 17: 2743-2747. doi: 10.1080/01431169608949104 [4] Tahnk W R, Coakley J A. Improved calibration coefficients for NOAA-14 AVHRR visible and near-infrared channels. Int. J. Remote Sensing, 2001, 22(7) : 1269-1283. doi: 10.1080/01431160151144341 -
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