云是海洋遥感的一项重要研究内容,云检测精度对于海洋上空云微物理特性的反演和海洋水体观测具有重要意义。以高分五号卫星搭载的大气气溶胶多角度偏振探测仪(Directional polarimetric camera,DPC)在轨成像数据为研究对象,提出了一种...云是海洋遥感的一项重要研究内容,云检测精度对于海洋上空云微物理特性的反演和海洋水体观测具有重要意义。以高分五号卫星搭载的大气气溶胶多角度偏振探测仪(Directional polarimetric camera,DPC)在轨成像数据为研究对象,提出了一种基于多角度偏振辐射信息的海洋上空云检测方法。首先用耀光角判别法区分出海洋耀光区域和非耀光区域,然后利用多角度偏振信息对耀光区域进行云检测,并基于反射率阈值、可见近红外反射率比值和偏振信息检验等方法对非耀光像元进行云检测。以印度洋和大西洋海域为例,基于DPC数据进行了海洋上空云检测,经过时空匹配后,其结果与MODIS(Moderate-resolution imaging spectroradiometer)云掩膜数据一致性分别为91.39%和94.73%。此外,用法国POLDER3(Polarization and directionality of the earth′s reflectances)数据验证了文中算法的有效性,将云检测结果和POLDER3官方云检测产品对比,一致性达到90.40%。文中提出的多角度偏振辐射阈值云检测算法,可为卫星观测的海洋上空云特性研究和海洋水体观测提供有效云检测数据。展开更多
This paper retrieves the bidirectional polarization distribution functions (BPDFs) of the distinct urban cover in the Pearl River Delta (PRD) region employing the high spatial resolution of multi-angle polarized measu...This paper retrieves the bidirectional polarization distribution functions (BPDFs) of the distinct urban cover in the Pearl River Delta (PRD) region employing the high spatial resolution of multi-angle polarized measurements made by the Directional Polarimetric Camera (DPC).The BPDF operational products of MICROPOL and POLDER measurements were used to validate the BPDF products of the DPC,with the results demonstrating that the BPDF product of the DPC measurements accurately expresses the surface polarized reflectance.The polarized reflectance of distinct surface types in the PRD region was studied using the DPC measurements.The results demonstrate that the polarized reflectances of different surface types differ and decrease as the normalized difference vegetation index increases.The polarized reflectance of a distinct surface type in the PRD region decreases with increasing scattering angle.The basic theory of investigating surface properties using multi-angle polarized measurements is proposed.展开更多
通过分析多角度偏振成像仪(DPC)的后验误差,测试DPC的气溶胶反演效果,为算法改进提供支持。使用GRASP(generalized retrieval of aerosol and surface properties)算法在同等条件下对DPC和POLDER(polarization and directionality of th...通过分析多角度偏振成像仪(DPC)的后验误差,测试DPC的气溶胶反演效果,为算法改进提供支持。使用GRASP(generalized retrieval of aerosol and surface properties)算法在同等条件下对DPC和POLDER(polarization and directionality of the earth's reflectance)数据进行反演,分析两种传感器的强度(RI)和偏振(RP)的反演残差及气溶胶光学厚度(AOD)误差;讨论山区和非山区AOD的反演精度及加入偏振信息对反演的改进。在多数波段,DPC的AOD反演精度接近POLDER,但在865 nm波段二者有较大正向偏差;RI@565、RI@865及RP@865的绝对值较大且较为离散;非山区上空DPC与POLDER反演精度接近,但在山区二者均出现系统性偏高,DPC尤为明显;偏振信息的加入可以有效改善仅强度条件下的反演结果;扣除干扰因素,非山区上空AOD@670落入期望误差范围的比例为63.7%,相关系数为0.828。展开更多
文摘云是海洋遥感的一项重要研究内容,云检测精度对于海洋上空云微物理特性的反演和海洋水体观测具有重要意义。以高分五号卫星搭载的大气气溶胶多角度偏振探测仪(Directional polarimetric camera,DPC)在轨成像数据为研究对象,提出了一种基于多角度偏振辐射信息的海洋上空云检测方法。首先用耀光角判别法区分出海洋耀光区域和非耀光区域,然后利用多角度偏振信息对耀光区域进行云检测,并基于反射率阈值、可见近红外反射率比值和偏振信息检验等方法对非耀光像元进行云检测。以印度洋和大西洋海域为例,基于DPC数据进行了海洋上空云检测,经过时空匹配后,其结果与MODIS(Moderate-resolution imaging spectroradiometer)云掩膜数据一致性分别为91.39%和94.73%。此外,用法国POLDER3(Polarization and directionality of the earth′s reflectances)数据验证了文中算法的有效性,将云检测结果和POLDER3官方云检测产品对比,一致性达到90.40%。文中提出的多角度偏振辐射阈值云检测算法,可为卫星观测的海洋上空云特性研究和海洋水体观测提供有效云检测数据。
基金supported by the National Basic Research Program of China(Grant No.2010CB950800)the National Natural Science Foundation of China(Grant No.41001207)the Funds of the Chinese Academy of Sciences for Key Topics in Innovation Engineering(Grant No.KZCX2-EW-QN311)
文摘This paper retrieves the bidirectional polarization distribution functions (BPDFs) of the distinct urban cover in the Pearl River Delta (PRD) region employing the high spatial resolution of multi-angle polarized measurements made by the Directional Polarimetric Camera (DPC).The BPDF operational products of MICROPOL and POLDER measurements were used to validate the BPDF products of the DPC,with the results demonstrating that the BPDF product of the DPC measurements accurately expresses the surface polarized reflectance.The polarized reflectance of distinct surface types in the PRD region was studied using the DPC measurements.The results demonstrate that the polarized reflectances of different surface types differ and decrease as the normalized difference vegetation index increases.The polarized reflectance of a distinct surface type in the PRD region decreases with increasing scattering angle.The basic theory of investigating surface properties using multi-angle polarized measurements is proposed.
文摘通过分析多角度偏振成像仪(DPC)的后验误差,测试DPC的气溶胶反演效果,为算法改进提供支持。使用GRASP(generalized retrieval of aerosol and surface properties)算法在同等条件下对DPC和POLDER(polarization and directionality of the earth's reflectance)数据进行反演,分析两种传感器的强度(RI)和偏振(RP)的反演残差及气溶胶光学厚度(AOD)误差;讨论山区和非山区AOD的反演精度及加入偏振信息对反演的改进。在多数波段,DPC的AOD反演精度接近POLDER,但在865 nm波段二者有较大正向偏差;RI@565、RI@865及RP@865的绝对值较大且较为离散;非山区上空DPC与POLDER反演精度接近,但在山区二者均出现系统性偏高,DPC尤为明显;偏振信息的加入可以有效改善仅强度条件下的反演结果;扣除干扰因素,非山区上空AOD@670落入期望误差范围的比例为63.7%,相关系数为0.828。
