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Reduction of structural impacts and distinction of photosynthetic pathways in a global estimation of GPP from space-borne solar-induced chlorophyll fluorescence

Authors :
Zhaoying Zhang
Yongguang Zhang
Albert Porcar-Castell
Joanna Joiner
Luis Guanter
Xi Yang
Mirco Migliavacca
Weimin Ju
Zhigang Sun
Shiping Chen
David Martini
Qian Zhang
Zhaohui Li
James Cleverly
Hezhou Wang
Yves Goulas
Source :
Remote Sensing of Environment. 240
Publication Year :
2020
Publisher :
United States: NASA Center for Aerospace Information (CASI), 2020.

Abstract

Quantifying global photosynthesis remains a challenge due to a lack of accurate remote sensing proxies. Solar-induced chlorophyll fluorescence (SIF) has been shown to be a good indicator of photosynthetic activity across various spatial scales. However, a global and spatially challenging estimate of terrestrial gross primary production (GPP) based on satellite SIF remains unresolved due to the confounding effects of species-specific physical and physiological traits and external factors, such as canopy structure or photosynthetic pathway (C3orC4). Here we analyze an ensemble of far-red SIF data from OCO-2 satellite and ground observations at multiple sites, using the spectral invariant theory to reduce the effects of canopy structure and to retrieve a structure-corrected total canopy SIF emission (SIF total). We find that the relationships between observed canopy-leavingSIF and ecosystem GPP vary significantly among biomes. In contrast, the relationships between SIF total and GPP converge around two unique models, one for C3and one for C4plants. We show that the two single empirical models can be used to globally scale satellite SIF observations to terrestrial GPP. We obtain an independent estimate of global terrestrial GPP of 129.56 ± 6.54 PgC/year for the 2015–2017 period, which is consistent with the state-of-the-art data- and process-oriented models. The new GPP product shows improved sensitivity to previously undetected ‘hotspots’ of productivity, being able to resolve the double-peak in GPP due to rotational cropping systems. We suggest that the direct scheme to estimate GPP presented here, which is based on satelliteSIF, may open up new possibilities to resolve the dynamics of global terrestrial GPP across space and time.

Subjects

Subjects :
Geosciences (General)

Details

Language :
English
Volume :
240
Database :
NASA Technical Reports
Journal :
Remote Sensing of Environment
Notes :
281945.02.61.04.96
Publication Type :
Report
Accession number :
edsnas.20210014809
Document Type :
Report
Full Text :
https://doi.org/10.1016/j.rse.2020.111722