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Biogeosciences An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/bg-2018-270
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2018-270
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 21 Jun 2018

Submitted as: research article | 21 Jun 2018

Review status
This discussion paper is a preprint. A revision of the manuscript for further review has not been submitted.

Estimating global gross primary productivity using chlorophyll fluorescence and a data assimilation system with the BETHY-SCOPE model

Alexander J. Norton1, Peter J. Rayner1, Ernest N. Koffi2, Marko Scholze3, Jeremy D. Silver1, and Ying-Ping Wang4 Alexander J. Norton et al.
  • 1School of Earth Sciences, University of Melbourne, Melbourne, Australia
  • 2European Commission Joint Research Centre, Ispra, Italy
  • 3Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden
  • 4CSIRO Oceans and Atmospheres, Aspendale, Australia

Abstract. This paper presents the assimilation of solar-induced chlorophyll fluorescence (SIF) into a terrestrial biosphere model to estimate the gross uptake of carbon through photosynthesis (GPP). We use the BETHY-SCOPE model to simulate both GPP and SIF in a process-based manner, going beyond a simple linear scaling between the two. We then use satellite SIF data from the Orbiting Carbon Observatory-2 (OCO-2) for 2015 in the data assimilation system to constrain model GPP. The assimilation results in considerable improvement between model and observed SIF, despite difficulties in simulating large SIF values due partly to uncertainties in the prescribed LAI. SIF-optimized global GPP increases by 7 % to 137 ± 6 PgCyr−1 and shows improvement in its global distribution relative to independent estimates. This change in global GPP is driven by an overall decline in APAR and increase in the light-use efficiency of photosynthesis across almost all ecosystems. This process-based data assimilation opens up new pathways to the effective utilization of satellite SIF data that will improve our understanding of the global carbon cycle.

Alexander J. Norton et al.
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Status: closed (peer review stopped)
Status: closed (peer review stopped)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Interactive discussion
Status: closed (peer review stopped)
Status: closed (peer review stopped)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Alexander J. Norton et al.
Alexander J. Norton et al.
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Short summary
This study presents a global estimate of land carbon uptake through photosynthesis. We make use satellite chlorophyll fluorescence measurements, a visible indicator of photosynthesis, to optimize model parameters and then use the optimized model to estimate photosynthetic carbon uptake. This provides a new tool that can combine measurements and observations in a systematic way and maximise the use of chlorophyll fluorescence to improve our understanding of the land carbon cycle.
This study presents a global estimate of land carbon uptake through photosynthesis. We make use...
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