title: Regional atmospheric CO2 inversion reveals seasonal and geographic differences in Amazon net biome exchange.
abstract: Understanding tropical rainforest carbon exchange and its response to heat and drought is critical for quantifying the effects of climate change on tropical ecosystems, including global climate-carbon feedbacks. Of particular importance for the global carbon budget is net biome exchange of CO2 with the atmosphere (NBE), which represents nonfire carbon fluxes into and out of biomass and soils. Subannual and sub-Basin Amazon NBE estimates have relied heavily on process-based biosphere models, despite lack of model agreement with plot-scale observations. We present a new analysis of airborne measurements that reveals monthly, regional-scale (~1-8 × 10(6)  km(2) ) NBE variations. We develop a regional atmospheric CO2 inversion that provides the first analysis of geographic and temporal variability in Amazon biosphere-atmosphere carbon exchange and that is minimally influenced by biosphere model-based first guesses of seasonal and annual mean fluxes. We find little evidence for a clear seasonal cycle in Amazon NBE but do find NBE sensitivity to aberrations from long-term mean climate. In particular, we observe increased NBE (more carbon emitted to the atmosphere) associated with heat and drought in 2010, and correlations between wet season NBE and precipitation (negative correlation) and temperature (positive correlation). In the eastern Amazon, pulses of increased NBE persisted through 2011, suggesting legacy effects of 2010 heat and drought. We also identify regional differences in postdrought NBE that appear related to long-term water availability. We examine satellite proxies and find evidence for higher gross primary productivity (GPP) during a pulse of increased carbon uptake in 2011, and lower GPP during a period of increased NBE in the 2010 dry season drought, but links between GPP and NBE changes are not conclusive. These results provide novel evidence of NBE sensitivity to short-term temperature and moisture extremes in the Amazon, where monthly and sub-Basin estimates have not been previously available.
authors.affiliation: Department of Earth System Science, Stanford University, Stanford, CA, 94305, USA.|Woods Institute for the Environment, Stanford University, Stanford, CA, 94305, USA.
authors.forename: Caroline B
authors.initials: CB
authors.lastname: Alden
authors.affiliation: Global Monitoring Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, CO, 80305, USA.|Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO, 80309, USA.
authors.forename: John B
authors.initials: JB
authors.lastname: Miller
authors.affiliation: Instituto de Pesquisas Energéticas e Nucleares (IPEN)-Comissao Nacional de Energia Nuclear (CNEN)-Atmospheric Chemistry Laboratory, 2242 Avenida Professor Lineu Prestes, Cidade Universitaria, Sao Paulo, CEP 05508-000, Brazil.
authors.forename: Luciana V
authors.initials: LV
authors.lastname: Gatti
authors.affiliation: School of Geography, University of Leeds, Woodhouse Lane, Leeds, LS9 2JT, UK.
authors.forename: Manuel M
authors.initials: MM
authors.lastname: Gloor
authors.affiliation: Department of Earth System Science, Stanford University, Stanford, CA, 94305, USA.
authors.forename: Kaiyu
authors.initials: K
authors.lastname: Guan
authors.affiliation: Department of Global Ecology, Carnegie Institution for Science, Stanford, CA, 94305, USA.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Michalak
authors.affiliation: Department of Meteorology and Air Quality, Wageningen University, PO Box 47, 6700AA, Wageningen, The Netherlands.
authors.forename: Ingrid T
authors.initials: IT
authors.lastname: van der Laan-Luijkx
authors.affiliation: Department of Earth System Science, Stanford University, Stanford, CA, 94305, USA.
authors.forename: Danielle
authors.initials: D
authors.lastname: Touma
authors.affiliation: Global Monitoring Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, CO, 80305, USA.
authors.forename: Arlyn
authors.initials: A
authors.lastname: Andrews
authors.affiliation: Instituto de Pesquisas Energéticas e Nucleares (IPEN)-Comissao Nacional de Energia Nuclear (CNEN)-Atmospheric Chemistry Laboratory, 2242 Avenida Professor Lineu Prestes, Cidade Universitaria, Sao Paulo, CEP 05508-000, Brazil.
authors.forename: Luana S
authors.initials: LS
authors.lastname: Basso
authors.affiliation: Instituto de Pesquisas Energéticas e Nucleares (IPEN)-Comissao Nacional de Energia Nuclear (CNEN)-Atmospheric Chemistry Laboratory, 2242 Avenida Professor Lineu Prestes, Cidade Universitaria, Sao Paulo, CEP 05508-000, Brazil.
authors.forename: Caio S C
authors.initials: CS
authors.lastname: Correia
authors.affiliation: Instituto de Pesquisas Energéticas e Nucleares (IPEN)-Comissao Nacional de Energia Nuclear (CNEN)-Atmospheric Chemistry Laboratory, 2242 Avenida Professor Lineu Prestes, Cidade Universitaria, Sao Paulo, CEP 05508-000, Brazil.
authors.forename: Lucas G
authors.initials: LG
authors.lastname: Domingues
authors.affiliation: National Aeronautics and Space Administration, Goddard Space Flight Center, Greenbelt, MD, 20771, USA.
authors.forename: Joanna
authors.initials: J
authors.lastname: Joiner
authors.affiliation: Department of Meteorology and Air Quality, Wageningen University, PO Box 47, 6700AA, Wageningen, The Netherlands.|Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Princetonplein 5, 3584 CC, Utrecht, The Netherlands.|SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht, The Netherlands.
authors.forename: Maarten C
authors.initials: MC
authors.lastname: Krol
authors.affiliation: National Aeronautics and Space Administration, Goddard Space Flight Center, Greenbelt, MD, 20771, USA.
authors.forename: Alexei I
authors.initials: AI
authors.lastname: Lyapustin
authors.affiliation: Department of Meteorology and Air Quality, Wageningen University, PO Box 47, 6700AA, Wageningen, The Netherlands.|University of Groningen, Centre for Isotope Research, Nijenborgh 4, 9747AG, Groningen, The Netherlands.
authors.forename: Wouter
authors.initials: W
authors.lastname: Peters
authors.affiliation: Department of Global Ecology, Carnegie Institution for Science, Stanford, CA, 94305, USA.|Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, 94305, USA.
authors.forename: Yoichi P
authors.initials: YP
authors.lastname: Shiga
authors.affiliation: Global Monitoring Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, CO, 80305, USA.
authors.forename: Kirk
authors.initials: K
authors.lastname: Thoning
authors.affiliation: University of Groningen, Centre for Isotope Research, Nijenborgh 4, 9747AG, Groningen, The Netherlands.
authors.forename: Ivar R
authors.initials: IR
authors.lastname: van der Velde
authors.affiliation: Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Princetonplein 5, 3584 CC, Utrecht, The Netherlands.|SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht, The Netherlands.
authors.forename: Thijs T
authors.initials: TT
authors.lastname: van Leeuwen
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA.
authors.forename: Vineet
authors.initials: V
authors.lastname: Yadav
authors.affiliation: Department of Earth System Science, Stanford University, Stanford, CA, 94305, USA.|Woods Institute for the Environment, Stanford University, Stanford, CA, 94305, USA.
authors.forename: Noah S
authors.initials: NS
authors.lastname: Diffenbaugh
mesh_terms: D057486:Carbon Cycle; D002245:Carbon Dioxide; D057231:Climate Change; D017753:Ecosystem; D012621:Seasons
chemical_list: D002245:Carbon Dioxide
keywords: Amazon; CO
  2; climate extremes; inverse model; terrestrial biosphere; tropical carbon exchange