The surface vegetation condition has been operationally monitored from space for many years by the Advanced Very High Resolution Radiometer (AVHRR) and the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments. As these instruments are close to the end of their design life, the surface vegetation products are required by many users from the new satellite missions. The MEdium Resolution Spectral Imager-II (MERSI-II) onboard the Fengyun (FY) satellite (FY-3 series; FY-3D) is used to retrieve surface vegetation parameters. First, MERSI-II solar channel measurements at the red and near-infrared (NIR) bands at the top of atmosphere (TOA) are corrected to the surface reflectances at the top of canopy (TOC) by removing the contributions of scattering and absorption of molecules and aerosols. The normalized difference vegetation index (NDVI) at both the TOA and TOC is then produced by using the same algorithms as the MODIS and AVHRR. The MERSI-II enhanced VI (EVI) at the TOC is also developed. The MODIS technique of compositing the NDVI at various timescales is applied to MERSI-II to generate the gridded products at different resolutions. The MERSI-II VI products are consistent with the MODIS data without systematic biases. Compared to the current MERSI-II EVI generated from the ground operational system, the MERSI-II EVI from this study has a much better agreement with MODIS after atmospheric correction.

中文翻译：

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来自Fengyun-3D中分辨率光谱成像仪-II的植被产品

先进的超高分辨率辐射计（AVHRR）和中等分辨率成像光谱辐射仪（MODIS）仪器已从太空对表面植被状况进行了多年的操作监控。由于这些仪器的设计寿命已接近尾声，因此新卫星任务的许多用户都需要表面植被产品。风云（FY）卫星（FY-3系列; FY-3D）上的中分辨率光谱成像仪II（MERSI-II））用于检索地表植被参数。首先，通过消除散射和吸收的贡献，将大气层顶部（TOA）的红色和近红外（NIR）波段的MERSI-II太阳通道测量值校正为冠层顶部（TOC）的表面反射率。分子和气溶胶。然后，使用与MODIS和AVHRR相同的算法，在TOA和TOC处产生归一化差异植被指数（NDVI）。还开发了TOC上的MERSI-II增强型VI（EVI）。将各种时间尺度上的NDVI合成的MODIS技术应用于MERSI-II，以生成不同分辨率的栅格化产品。MERSI-II VI产品与MODIS数据一致，没有系统偏差。与地面操作系统生成的当前MERSI-II EVI相比，