TransCom 3 CO$_2$ inversion intercomparison: 1. Annual mean control results and sensitivity to transport and prior flux information

• Published in: Tellus B: Chemical and Physical Meteorology
• Main Authors: Gurney, K., Law, R., Denning, A., Rayner, P., Baker, D., Bousquet, P., Bruhwiler, L., Chen, Y.-H., Ciais, P., Fan, S., Fung, I., Gloor, M., Heimann, M., Higuchi, K., John, J., Kowalczyk, E., Maki, T., Maksyutov, S., Peylin, Philippe, Prather, M., Pak, B., Sarmiento, J., Taguchi, S., Takahashi, T., Yuen, C.-W.
• Other Authors: Department of Atmospheric Science Fort Collins, Colorado State University Fort Collins (CSU), CSIRO Marine and Atmospheric Research Aspendale, Commonwealth Scientific and Industrial Research Organisation Canberra (CSIRO), National Center for Atmospheric Research Boulder (NCAR), Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation INVerse pour les mesures atmosphériques et SATellitaires (SATINV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), National Oceanic and Atmospheric Administration (NOAA), Department of Earth, Atmospheric and Planetary Sciences MIT, Cambridge (EAPS), Massachusetts Institute of Technology (MIT), ICOS-ATC (ICOS-ATC), Atmospheric and Oceanic Sciences Program Princeton (AOS Program), NOAA Geophysical Fluid Dynamics Laboratory (GFDL), National Oceanic and Atmospheric Administration (NOAA)-National Oceanic and Atmospheric Administration (NOAA)-Princeton University, University of California Berkeley, University of California, Biogeochemical Systems Department Jena, Max Planck Institute for Biogeochemistry (MPI-BGC), Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Meteorological Service of Canada (MSC), Environment and Climate Change Canada, Japan Meteorological Agency (JMA), Research Institute for Global Change (RIGC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Biogéochimie et écologie des milieux continentaux (Bioemco), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Modélisation des Surfaces et Interfaces Continentales (MOSAIC), University of California Irvine (UCI), National Institute of Advanced Industrial Science and Technology (AIST), Lamont-Doherty Earth Observatory (LDEO), Columbia University New York, Department of Physics Tokyo, Gakushuin University
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2003
• Subjects: Sinks; Tracer; Cumulus Parameterization; Boundary-Layer; Atmospheric Co2; General-Circulation Model; Simulation; Surface; Scale; [SDE.MCG]Environmental Sciences/Global Changes; Southern Ocean
• Online Access: https://hal-bioemco.ccsd.cnrs.fr/bioemco-00175987; https://hal-bioemco.ccsd.cnrs.fr/bioemco-00175987/document; https://hal-bioemco.ccsd.cnrs.fr/bioemco-00175987/file/2003_Gurney_Tellus_1.pdf; https://doi.org/10.3402/tellusb.v55i2.16728

International audience Spatial and temporal variations of atmospheric CO$_2$ concentrations contain information about surface sources and sinks, which can be quantitatively interpreted through tracer transport inversion. Previous CO$_2$ inversion calculations obtained differing results due to different data, methods and transport models used. To isolate the sources of uncertainty, we have conducted a set of annual mean inversion experiments in which 17 different transport models or model variants were used to calculate regional carbon sources and sinks from the same data with a standardized method. Simulated transport is a significant source of uncertainty in these calculations, particularly in the response to prescribed "background" fluxes due to fossil fuel combustion, a balanced terrestrial biosphere, and air-sea gas exchange. Individual model-estimated fluxes are often a direct reflection of their response to these background fluxes. Models that generate strong surface maxima near background exchange locations tend to require larger uptake near those locations. Models with weak surface maxima tend to have less uptake in those same regions but may infer small sources downwind. In some cases, individual model flux estimates cannot be analyzed through simple relationships to background flux responses but are likely due to local transport differences or particular responses at individual CO$_2$ observing locations. The response to the background biosphere exchange generates the greatest variation in the estimated fluxes, particularly over land in the Northern Hemisphere. More observational data in the tropical regions may help in both lowering the uncertain tropical land flux uncertainties and constraining the northern land estimates because of compensation between these two broad regions in the inversion. More optimistically, examination of the model-mean retrieved fluxes indicates a general insensitivity to the prior fluxes and the prior flux uncertainties. Less uptake in the Southern Ocean than implied by ...