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Global-Scale Consistency of Spaceborne Vegetation Indices, Chlorophyll Fluorescence, and Photosynthesis

Doughty, Russell and Xiao, Xiangming and Köhler, Philipp and Frankenberg, Christian and Qin, Yuanwei and Wu, Xiaocui and Ma, Shuang and Moore, Berrien, III (2021) Global-Scale Consistency of Spaceborne Vegetation Indices, Chlorophyll Fluorescence, and Photosynthesis. Journal of Geophysical Research: Biogeosciences, 126 (6). Art. No. e2020JG006136. ISSN 2169-8953. doi:10.1029/2020jg006136.

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The new TROPOspheric Monitoring Instrument (TROPOMI) solar-induced chlorophyll fluorescence (SIF) data provides new opportunities to corroborate and improve global photosynthesis estimates. Here we report the spatiotemporal consistency between TROPOMI SIF and vegetation indices from the bidirectional reflectance distribution function (BRDF) adjusted (MCD43) and standard MODIS (MOD09) surface reflectance products, estimates of absorbed photosynthetically active radiation by chlorophyll (APAR_(chl)) derived from National Centers for Environmental Prediction Reanalysis-2 (NCEP2), MODIS MCD18, and European Reanalysis (ERA5) data, and two GPP products (GPP_(VPM) and GPP_(MOD17)). We find (a) non-adjusted VIs were more highly correlated with SIF at mid and high latitude than BRDF-adjusted VIs, but were less correlated in the tropics, (b) negligible differences in the correlation between SIF and non-adjusted NIRv and EVI, but BRDF-adjusted NIRv had higher correlations with SIF at mid to high latitude than BRDF-adjusted EVI but lower correlations in the tropics, (c) choice of PAR data set likely to cause substantial differences in global and regional GPP estimates and the correlation between modeled GPP and SIF, (d) SIF was more highly correlated with APAR_(chl) at high to mid latitude than EVI but more highly correlated with EVI at lower latitudes, and (e) GPP_(VPM) is more highly correlated with SIF than GPP_(MOD17), except in sub-Sahara Africa. Our results highlight that spaceborne photosynthesis would likely be improved by using a non-linear response to PAR and that the fundamental differences between the vegetation indices and PAR data sets are likely to yield important differences in global and regional estimates of photosynthesis.

Item Type:Article
Related URLs:
URLURL TypeDescription ItemTROPOMI SIF data data ItemMOD17A2H data ItemMCD18A2 data ItemERA5 data ItemNCEP Reanalysis II data ItemMCD43C4 data ItemMOD09A1 data
Doughty, Russell0000-0001-5191-2155
Xiao, Xiangming0000-0003-0956-7428
Köhler, Philipp0000-0002-7820-1318
Frankenberg, Christian0000-0002-0546-5857
Qin, Yuanwei0000-0002-5181-9986
Wu, Xiaocui0000-0001-7447-0257
Ma, Shuang0000-0002-6494-724X
Moore, Berrien, III0000-0001-7870-8920
Additional Information:© 2021 American Geophysical Union. Issue Online: 25 June 2021; Version of Record online: 25 June 2021; Accepted manuscript online: 08 June 2021; Manuscript accepted: 02 June 2021; Manuscript revised: 03 May 2021; Manuscript received: 28 October 2020. The authors are grateful to Vincent Humphrey for preparing the ERA5 data for analysis. This study was supported by research grants through the Geostationary Carbon Cycle Observatory (GeoCarb) Mission from NASA (GeoCarb Contract #80LARC17C0001), the US National Science Foundation: EPSCoR Program (IIA-1920946, IIA-1946093) and EEID program (1911955), the USDA National Institute of Food and Agriculture (2016-68002-24967), and the NASA OCO Science Team (80NSSC18K0895). Philipp Köhler and Christian Frankenberg were funded by the EARTH SCIENCE U.S. PARTICIPATING INVESTIGATOR (Grant: NNX15AH95G). Data Availability Statement: The analysis and results were generated using publicly available data sets. TROPOMI SIF data is available at, and aside from this FTP address there is no alternative method to access the data. The GPPVPM data is available at MOD17A2H data is available at MCD18A2 data is available at ERA5 data is available at NCEP Reanalysis II data is available at MCD43C4 data is available at MOD09A1 data is available at
Funding AgencyGrant Number
United States Department of Agriculture (USDA)2016-68002-24967
Subject Keywords:gross primary production; photosynthetically active radiation; vegetation photosynthesis model; Sentinel-5 Precursor; solar-induced chlorophyll fluorescence; TROPOMI
Issue or Number:6
Record Number:CaltechAUTHORS:20210610-123358381
Persistent URL:
Official Citation:Doughty, R., Xiao, X., Köhler, P., Frankenberg, C., Qin, Y., Wu, X., et al. (2021). Global-scale consistency of spaceborne vegetation indices, chlorophyll fluorescence, and photosynthesis. Journal of Geophysical Research: Biogeosciences, 126, e2020JG006136.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109468
Deposited By: Tony Diaz
Deposited On:10 Jun 2021 20:57
Last Modified:01 Dec 2021 08:05

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