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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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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