Linking global terrestrial CO2 fluxes and environmental drivers: Inferences from the Orbiting Carbon Observatory 2 satellite and terrestrial biospheric models

Zichong Chen, Junjie Liu, Daven K. Henze, Deborah N. Huntzinger, Kelley C. Wells, Stephen Sitch, Pierre Friedlingstein, Emilie Joetzjer, Vladislav Bastrikov, Daniel S. Goll, Vanessa Haverd, Atul K. Jain, Etsushi Kato, Sebastian Lienert, Danica L. Lombardozzi, Patrick C. Mcguire, Joe R. Melton, Julia E.M.S. Nabel, Benjamin Poulter, Hanqin TianAndrew J. Wiltshire, Sönke Zaehle, Scot M. Miller

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Observations from the Orbiting Carbon Observatory 2 (OCO-2) satellite have been used to estimate CO2 fluxes in many regions of the globe and provide new insight into the global carbon cycle. The objective of this study is to infer the relationships between patterns in OCO-2 observations and environmental drivers (e.g., temperature, precipitation) and therefore inform a process understanding of carbon fluxes using OCO-2. We use a multiple regression and inverse model, and the regression coefficients quantify the relationships between observations from OCO-2 and environmental driver datasets within individual years for 2015- 2018 and within seven global biomes.We subsequently compare these inferences to the relationships estimated from 15 terrestrial biosphere models (TBMs) that participated in the TRENDY model inter-comparison. Using OCO-2, we are able to quantify only a limited number of relationships between patterns in atmospheric CO2 observations and patterns in environmental driver datasets (i.e., 10 out of the 42 relationships examined). We further find that the ensemble of TBMs exhibits a large spread in the relationships with these key environmental driver datasets. The largest uncertainty in the models is in the relationship with precipitation, particularly in the tropics, with smaller uncertainties for temperature and photosynthetically active radiation (PAR). Using observations from OCO-2, we find that precipitation is associated with increased CO2 uptake in all tropical biomes, a result that agrees with half of the TBMs. By contrast, the relationships that we infer from OCO-2 for temperature and PAR are similar to the ensemble mean of the TBMs, though the results differ from many individual TBMs. These results point to the limitations of current space-based observations for inferring environmental relationships but also indicate the potential to help inform key relationships that are very uncertain in stateof- the-art TBMs.

Original languageEnglish (US)
Pages (from-to)6663-6680
Number of pages18
JournalAtmospheric Chemistry and Physics
Volume21
Issue number9
DOIs
StatePublished - May 4 2021

Bibliographical note

Funding Information:
Financial support. This research has been supported by NASA ROSES (grant no. 80NSSC18K0976).

Funding Information:
Acknowledgements. We thank Kim Mueller and Anna Michalak for their feedback on the research; David Baker for his help with the XCO2 data; Colm Sweeny and Kathryn McKain for their help with aircraft datasets from the NOAA/ESRL Global Greenhouse Gas Reference Network; John Miller, Luciana Gatti, Wouter Peters, and Manuel Gloor for their help with the aircraft data from the INPE ObsPack data product; Steven Wofsy, Kathryn McKain, Colm Sweeny, and Róisín Commane for their help with ATom aircraft datasets; and Debra Wunch for her help with the TCCON datasets. Daven Henze’s work is supported by NOAA grant no. NA16OAR4310113. Daniel Goll’s work is supported by the ANR CLAND Convergence Institute. The data analysis and inverse modeling were performed on the NASA Pleiades Supercomputer.

Publisher Copyright:
© Author(s) 2021.

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