为研究小麦条锈病病情严重度和日光诱导叶绿素荧光强度的关系,确定适合于探测小麦条锈病病情严重度的叶绿素荧光因子。本文分别利用3FLD(three bands Fraunhofer Line Discrimination)和反射率指数2种方法提取了日光诱导叶绿素荧光强度...为研究小麦条锈病病情严重度和日光诱导叶绿素荧光强度的关系,确定适合于探测小麦条锈病病情严重度的叶绿素荧光因子。本文分别利用3FLD(three bands Fraunhofer Line Discrimination)和反射率指数2种方法提取了日光诱导叶绿素荧光强度,对比分析了这2种方法估测的日光诱导叶绿素荧光强度在小麦条锈病病情严重度遥感探测中的应用潜力。利用3FLD方法计算的O2-A和O2-B波段叶绿素荧光强度与小麦条锈病病情严重度均达到了极显著相关,复相关系数分别为0.6772和0.4924。基于反射率指数估测日光诱导叶绿素荧光时,叶绿素荧光反射率比值指数R740/R720、R440/R690、R740/R800以及叶绿素荧光一阶导数光谱指数D705/D722、D730/D706与小麦条锈病病情严重度均达到了极显著相关,尤其是比值指数R440/R690与小麦条锈病病情指数的相关性最高,复相关系数达到了0.7187。基于辐亮度的3FLD算法和基于反射率的叶绿素荧光比值指数2种方法提取的叶绿素荧光强度均能够实现小麦条锈病病情严重度的遥感探测,但利用反射率方法提取的日光诱导叶绿素荧光强度构建的小麦条锈病病情严重度估测模型优于3FLD算法,更适合小麦条锈病病情严重度的遥感探测。论文的研究结果为基于卫星平台的叶绿素荧光遥感探测小麦条锈病提供了重要的理论依据。展开更多
为了实现对光学传感器在轨性能的连续监测,文章使用敦煌场地的自动化观测数据对"风云三号"卫星可见光红外扫描辐射计(Visible and Infrared Radiometer,VIRR)近三年的数据进行了连续定标跟踪,推算VIRR各通道的定标斜率,基于...为了实现对光学传感器在轨性能的连续监测,文章使用敦煌场地的自动化观测数据对"风云三号"卫星可见光红外扫描辐射计(Visible and Infrared Radiometer,VIRR)近三年的数据进行了连续定标跟踪,推算VIRR各通道的定标斜率,基于敦煌辐射校正场自动化观测的定标相较于传统现场试验定标方法具有明显提高定标频次优势。采用搭载于Aqua卫星的高精度的中分辨率成像光谱仪(Aqua Moderate Resolution Imaging Spectroradiometer,Aqua MODIS)观测对自动观测定标方法进行精度验证,表明该方法在可见光近红外(Visible and Near Infrared,VNIR)具有3%的定标精度,在短波红外(Short Wave Infrared,SWIR)具有5%的定标精度。将该方法的结果与业务多场地方法的结果进行比较,在3年尺度上均值相对偏差整体低于2%。对VIRR的跟踪结果表明:基于场地自动化观测能够实现长期定标监测,可将该方法推广应用于其他卫星光学载荷以真正实现多载荷的场地自动化定标业务化。展开更多
The visible infrared radiometer(VIRR)is the first instrument with longest measurements equipped on the Fengyun(FY)polar-orbiting satellites.Through re-processing of the historic VIRR measurements,long-term(over 20 yr)...The visible infrared radiometer(VIRR)is the first instrument with longest measurements equipped on the Fengyun(FY)polar-orbiting satellites.Through re-processing of the historic VIRR measurements,long-term(over 20 yr)global data can be integrated from multiple participating VIRRs on a consistent radiometric scale,which are valuable to climate and climate change studies.Due to lack of an onboard calibration system for VIRR,the reflective solar bands must be vicariously calibrated.This study applied the multi-site vicarious approach for consistent calibration of the VIRR visible(VIS)and near-infrared(NIR)data,and produced calibration coefficients for five VIRRs on FY-1 C/D and FY-3 A/B/C.The data quality was then evaluated with observations.The reflectance predicted by using the radiative transfer model over multiple invariant desert and ocean targets was used to derive the calibration slope via a weighted fitting scheme,in which the weights are the inverse of the variance from a radiative transfer simulation evaluated with reference to Aqua moderate resolution imaging spectroradiometer(MODIS).The sensor-specific calibration coefficients were derived on a daily basis by using piecewise polynomials.The calibration reference of the VIRR solar band record was further traced to the Aqua MODIS Collection 6.1 reference calibration with a systematic correction derived from the Libya4 desert.The VIRR record was compared with the Aqua MODIS C6.1 calibration over the polar region based on simultaneous nadir overpass observations.The lifetime relative difference for each sensor are within 3.3%and 4.5%for channels 1 and 2.Invariant deserts were also employed to evaluate the stability and consistency of the VIRR record.In general,the means of the directional and spectral corrected reflectance for each sensor are within 1%of the 20-yr average,implying that the VIRR reflectance of the invariant targets is consistent to within 1%among the sensors for channels 1 and 2.The VIRR data thus derived are reliable.展开更多
文摘为研究小麦条锈病病情严重度和日光诱导叶绿素荧光强度的关系,确定适合于探测小麦条锈病病情严重度的叶绿素荧光因子。本文分别利用3FLD(three bands Fraunhofer Line Discrimination)和反射率指数2种方法提取了日光诱导叶绿素荧光强度,对比分析了这2种方法估测的日光诱导叶绿素荧光强度在小麦条锈病病情严重度遥感探测中的应用潜力。利用3FLD方法计算的O2-A和O2-B波段叶绿素荧光强度与小麦条锈病病情严重度均达到了极显著相关,复相关系数分别为0.6772和0.4924。基于反射率指数估测日光诱导叶绿素荧光时,叶绿素荧光反射率比值指数R740/R720、R440/R690、R740/R800以及叶绿素荧光一阶导数光谱指数D705/D722、D730/D706与小麦条锈病病情严重度均达到了极显著相关,尤其是比值指数R440/R690与小麦条锈病病情指数的相关性最高,复相关系数达到了0.7187。基于辐亮度的3FLD算法和基于反射率的叶绿素荧光比值指数2种方法提取的叶绿素荧光强度均能够实现小麦条锈病病情严重度的遥感探测,但利用反射率方法提取的日光诱导叶绿素荧光强度构建的小麦条锈病病情严重度估测模型优于3FLD算法,更适合小麦条锈病病情严重度的遥感探测。论文的研究结果为基于卫星平台的叶绿素荧光遥感探测小麦条锈病提供了重要的理论依据。
文摘为了实现对光学传感器在轨性能的连续监测,文章使用敦煌场地的自动化观测数据对"风云三号"卫星可见光红外扫描辐射计(Visible and Infrared Radiometer,VIRR)近三年的数据进行了连续定标跟踪,推算VIRR各通道的定标斜率,基于敦煌辐射校正场自动化观测的定标相较于传统现场试验定标方法具有明显提高定标频次优势。采用搭载于Aqua卫星的高精度的中分辨率成像光谱仪(Aqua Moderate Resolution Imaging Spectroradiometer,Aqua MODIS)观测对自动观测定标方法进行精度验证,表明该方法在可见光近红外(Visible and Near Infrared,VNIR)具有3%的定标精度,在短波红外(Short Wave Infrared,SWIR)具有5%的定标精度。将该方法的结果与业务多场地方法的结果进行比较,在3年尺度上均值相对偏差整体低于2%。对VIRR的跟踪结果表明:基于场地自动化观测能够实现长期定标监测,可将该方法推广应用于其他卫星光学载荷以真正实现多载荷的场地自动化定标业务化。
基金Supported by the National Key Research and Development Program of China(2018YFB0504905 and 2018YFB0504900)。
文摘The visible infrared radiometer(VIRR)is the first instrument with longest measurements equipped on the Fengyun(FY)polar-orbiting satellites.Through re-processing of the historic VIRR measurements,long-term(over 20 yr)global data can be integrated from multiple participating VIRRs on a consistent radiometric scale,which are valuable to climate and climate change studies.Due to lack of an onboard calibration system for VIRR,the reflective solar bands must be vicariously calibrated.This study applied the multi-site vicarious approach for consistent calibration of the VIRR visible(VIS)and near-infrared(NIR)data,and produced calibration coefficients for five VIRRs on FY-1 C/D and FY-3 A/B/C.The data quality was then evaluated with observations.The reflectance predicted by using the radiative transfer model over multiple invariant desert and ocean targets was used to derive the calibration slope via a weighted fitting scheme,in which the weights are the inverse of the variance from a radiative transfer simulation evaluated with reference to Aqua moderate resolution imaging spectroradiometer(MODIS).The sensor-specific calibration coefficients were derived on a daily basis by using piecewise polynomials.The calibration reference of the VIRR solar band record was further traced to the Aqua MODIS Collection 6.1 reference calibration with a systematic correction derived from the Libya4 desert.The VIRR record was compared with the Aqua MODIS C6.1 calibration over the polar region based on simultaneous nadir overpass observations.The lifetime relative difference for each sensor are within 3.3%and 4.5%for channels 1 and 2.Invariant deserts were also employed to evaluate the stability and consistency of the VIRR record.In general,the means of the directional and spectral corrected reflectance for each sensor are within 1%of the 20-yr average,implying that the VIRR reflectance of the invariant targets is consistent to within 1%among the sensors for channels 1 and 2.The VIRR data thus derived are reliable.
