title: Precipitation and carbon-water coupling jointly control the interannual variability of global land gross primary production.
abstract: Carbon uptake by terrestrial ecosystems is increasing along with the rising of atmospheric CO2concentration. Embedded in this trend, recent studies suggested that the interannual variability (IAV) of global carbon fluxes may be dominated by semi-arid ecosystems, but the underlying mechanisms of this high variability in these specific regions are not well known. Here we derive an ensemble of gross primary production (GPP) estimates using the average of three data-driven models and eleven process-based models. These models are weighted by their spatial representativeness of the satellite-based solar-induced chlorophyll fluorescence (SIF). We then use this weighted GPP ensemble to investigate the GPP variability for different aridity regimes. We show that semi-arid regions contribute to 57% of the detrended IAV of global GPP. Moreover, in regions with higher GPP variability, GPP fluctuations are mostly controlled by precipitation and strongly coupled with evapotranspiration (ET). This higher GPP IAV in semi-arid regions is co-limited by supply (precipitation)-induced ET variability and GPP-ET coupling strength. Our results demonstrate the importance of semi-arid regions to the global terrestrial carbon cycle and posit that there will be larger GPP and ET variations in the future with changes in precipitation patterns and dryland expansion.
authors.affiliation: Department of Microbiology and Plant Biology, Center for Spatial Analysis, University of Oklahoma, Norman, OK 73019, USA.
authors.forename: Yao
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Microbiology and Plant Biology, Center for Spatial Analysis, University of Oklahoma, Norman, OK 73019, USA.|Institute of Biodiversity Science, Fudan University, Shanghai, 200433, China.
authors.forename: Xiangming
authors.initials: X
authors.lastname: Xiao
authors.affiliation: Helmholtz Centre Potsdam, German Research Center for Geosciences (GFZ), Telegrafenberg A17, 14473 Potsdam, Germany.
authors.forename: Luis
authors.initials: L
authors.lastname: Guanter
authors.affiliation: State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing, China.
authors.forename: Sha
authors.initials: S
authors.lastname: Zhou
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement, CEA CNRS UVSQ, Gif-sur-Yvette 91190, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Ciais
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, MD, USA.
authors.forename: Joanna
authors.initials: J
authors.lastname: Joiner
authors.affiliation: College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4RJ, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Sitch
authors.affiliation: Department of Microbiology and Plant Biology, Center for Spatial Analysis, University of Oklahoma, Norman, OK 73019, USA.
authors.forename: Xiaocui
authors.initials: X
authors.lastname: Wu
authors.affiliation: Max Planck Institute for Meteorology, Bundesstr. 53, 20146 Hamburg, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Nabel
authors.affiliation: Department of Microbiology and Plant Biology, Center for Spatial Analysis, University of Oklahoma, Norman, OK 73019, USA.
authors.forename: Jinwei
authors.initials: J
authors.lastname: Dong
authors.affiliation: Global Environment Program, Institute of Applied Energy (IAE), Minato, Tokyo 105-0003, Japan.
authors.forename: Etsushi
authors.initials: E
authors.lastname: Kato
authors.affiliation: Department of Atmospheric Sciences, University of Illinois, Urbana, IL 61821, USA.
authors.forename: Atul K
authors.initials: AK
authors.lastname: Jain
authors.affiliation: Met Office Hadley Centre, FitzRoy Road, Exeter EX1 3PB, UK.
authors.forename: Andy
authors.initials: A
authors.lastname: Wiltshire
authors.affiliation: Department of Life Sciences, Imperial College London, Silwood Park, Ascot SL5 7PY, UK.
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Stocker