The chlorophyll/carotenoid index(CCI)is increasingly used for remotely tracking the phenology of photosynthesis.However,CCI is restricted to few satellites incorporating the 531nm band.This study reveals that the Mode...The chlorophyll/carotenoid index(CCI)is increasingly used for remotely tracking the phenology of photosynthesis.However,CCI is restricted to few satellites incorporating the 531nm band.This study reveals that the Moderate Resolution Imaging Spectroradiometer(MODIS)broadband green reflectance(band 4)is significantly correlated with this xanthophyll-sensitive narrowband(band 11)(R^(2)=0:98,p<0:001),and consequently,the broadband green-red vegetation index GRVI—computed with MODIS band 1 and band 4—is significantly correlated with CCI—computed with MODIS band 1 and band 11(R^(2)=0:97,p<0:001).GRVI and CCI performed similarly in extracting phenological metrics of the dates of the start and end of the season(EOS)when evaluated with gross primary production(GPP)measurements from eddy covariance towers.For EOS extraction of evergreen needleleaf forest,GRVI even overperformed solar-induced chlorophyll fluorescence which is seen as a direct proxy of plant photosynthesis.This study opens the door for GPP and photosynthetic phenology monitoring from a wide set of sensors with broadbands in the green and red spectral regions.展开更多
基金This work was supported by the Sichuan Science and Technology Program(2021JDJQ0007 and 2020JDTD0003)the National Natural Science Foundation of China(41971282)+6 种基金the Marie Skłodowska-Curie Grant of the European Union’s Horizon 2020 Research and Innovation Programme(835541)Funding from the Spanish Government(grant PID2019-110521GB-I00)Fundación Ramon Areces(grant ELEMENTAL-CLIMATE)Catalan Government(grants SGR 2017-1005 and AGAUR-2020PANDE00117)European Research Council(Synergy grant ERC-SyG-2013-610028,IMBALANCE-P)is also acknowledgedThis work represents a contribution to CSIC-PTI TELEDETECTIn situ observations of fluxes were obtained from the FLUXNET 2015 dataset(http://fluxnet.fluxdata.org/data/fluxnet2015-dataset/).The MCD19A1 C6 product is also available online(https://ladsweb.modaps.eosdis.nasa.gov/search/).Jiangliu Xie,Hongfan Gu,and Huiqin Pan are appreciated for collecting the data.
文摘The chlorophyll/carotenoid index(CCI)is increasingly used for remotely tracking the phenology of photosynthesis.However,CCI is restricted to few satellites incorporating the 531nm band.This study reveals that the Moderate Resolution Imaging Spectroradiometer(MODIS)broadband green reflectance(band 4)is significantly correlated with this xanthophyll-sensitive narrowband(band 11)(R^(2)=0:98,p<0:001),and consequently,the broadband green-red vegetation index GRVI—computed with MODIS band 1 and band 4—is significantly correlated with CCI—computed with MODIS band 1 and band 11(R^(2)=0:97,p<0:001).GRVI and CCI performed similarly in extracting phenological metrics of the dates of the start and end of the season(EOS)when evaluated with gross primary production(GPP)measurements from eddy covariance towers.For EOS extraction of evergreen needleleaf forest,GRVI even overperformed solar-induced chlorophyll fluorescence which is seen as a direct proxy of plant photosynthesis.This study opens the door for GPP and photosynthetic phenology monitoring from a wide set of sensors with broadbands in the green and red spectral regions.
