Vegetation Products Derived from Fengyun-3D Medium Resolution Spectral Imager-II
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Advanced Applications of Meteorological Satellite Observations in Ecological Remote Sensing
AUGUST 2020
Vegetation Products Derived from Fengyun-3D Medium Resolution Spectral Imager-II Xiuzhen HAN, Jun YANG*, Shihao TANG, and Yang HAN National Satellite Meteorological Center, China Meteorological Administration, Beijing 100081 (Received February 15, 2020; in final form April 2, 2020)
ABSTRACT 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. Key words: MEdium Resolution Spectral Imager-II (MERSI-II), Fengyun (FY) satellite, vegetation index (VI), atmospheric correction Citation: Han, X. Z., J. Yang, S. H. Tang, et al., 2020: Vegetation products derived from Fengyun-3D Medium Resolution Spectral Imager-II. J. Meteor. Res., 34(4), 775–785, doi: 10.1007/s13351-020-0027-5.
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Introduction
The satellite vegetation index (VI) products derived from the Advanced Very High Resolution Radiometer (AVHRR) on board the NOAA satellites and NASA Moderate Resolution Imaging Spectroradiometer (MODIS) have provided consistent spatial and temporal comparisons of global vegetation conditions. Gridded VI maps depicting spatial and temporal variations in vegetation activity are derived at 16-day and monthly intervals for precise seasonal and interannual monitoring of the earth’s vegetation. Vegetation indices, such as normalized difference VI (NDVI), enhanced VI (EVI), and green vegetation fraction (GVF), are widely used to measure the canopy or vegetation variables. NDVI, originally developed by Rouse et al. (1973), was used to quantitat-
ively assess the biophysics characteristics of the Great Plains of North America. In addition, it is defined by the ratio of the differe
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