Towards robust regional estimates of CO2 sources and sinks using atmospheric transport models

By Kevin R. Gurney, R. Law, A. Denning, Peter J. Rayner, David Baker, P. Bousquet, L. Bruhwiler, Yu-Han Chen, Philippe Ciais, S. Fan and 16 more. Nature, 2002

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Information about regional carbon sources and sinks can be derived from variations in observed atmospheric CO2 concentrations via inverse modelling with atmospheric tracer transport models. A consensus has not yet been reached regarding the size and distribution of regional carbon fluxes obtained using this approach, partly owing to the use of several different atmospheric transport models. Here we report estimates of surface–atmosphere CO2 fluxes from an intercomparison of atmospheric CO2 inversion models (the TransCom 3 project), which includes 16 transport models and model variants. We find an uptake of CO2 in the southern extratropical ocean less than that estimated from ocean measurements, a result that is not sensitive to transport models or methodological approaches. We also find a northern land carbon sink that is distributed relatively evenly among the continents of the Northern Hemisphere, but these results show some sensitivity to transport differences among models, especially in how they respond to seasonal terrestrial exchange of CO2. Overall, carbon fluxes integrated over latitudinal zones are strongly constrained by observations in the middle to high latitudes. Further significant constraints to our understanding of regional carbon fluxes will therefore require improvements in transport models and expansion of the CO2 observation network within the tropics.

Subfields: Atmospheric Science, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/5b79adc22ab807fa49273ed3f389d707943beaee

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Citations in the corpus

A variational finite element method for source inversion for convective-diffusive transport (2003, neutral): “Email addresses: volkan@andrew.cmu.edu (Volkan Akçelik), biros@cs.nyu.edu (George Biros), oghattas@cs.cmu.edu (Omar Ghattas), Preprint submitted to Elsevier Science 7 January 2003”
On the use of 14CO2 as a tracer for fossil fuel CO2: Quantifying uncertainties using an atmospheric transport model (2009, methodology): “The model has been validated for CO2 transport, and compared with the TransCom intercomparison results [Bousquet et al., 2008; Gurney et al., 2002].”
Ecological research in the large-scale biosphere-atmosphere experiment in Amazonia: early results (2004, background): “…of the locations of observing stations, even large fluxes are currently below the resolution of global atmospheric inversion models for the Amazon region (Rayner et al. 1999, Bousquet et al. 2000, Gurney et al. 2002) but not below the threshold for measurement using regional airborne sampling.”
Chronic nitrogen additions reduce total soil respiration and microbial respiration in temperate forest soils at the Harvard Forest (2004, background): “…policy discussions because revegetation of abandoned agricultural areas is enabling these forests to serve as sinks for atmospheric C (Houghton, 1996; McGuire et al., 2001; Gurney et al., 2002), with sequestration rates up to 0.3 Pg C per year (Dixon et al., 1994; Nadelhoffer et al., 1999).”
Accounting for the effect of transport errors on tracer inversions (2005, methodology): “Time-averages (e.g., annual averages) are commonly applied [e.g., Gurney et al., 2002]; thus signals found in deviations from the time-average are essentially neglected.”
‘Breathing’ of the terrestrial biosphere: lessons learned from a global network of carbon dioxide flux measurement systems (2008, background): “net atmosphere–biosphere carbon exchange, derived from inversion model studies, for the European continent, range between –19 and –53 gC m−2 year−1 (Bousquet et al. 2000; Gurney et al. 2002; Janssens et al. 2003).”
Impact of correlated observation errors on inverted CO2 surface fluxes from OCO measurements (2007, methodology): “For the estimation of CO2 surface fluxes from measurements of atmospheric concentrations, diagonal error matrices have been empirically used until recently [e.g., Gurney et al., 2002].”
Latitudinal patterns of magnitude and interannual variability in net ecosystem exchange regulated by biological and environmental variables (2009, background): “Recent studies, using different approaches including biomass inventory, ecological models and inversions with atmospheric transport models, are inconclusive regarding the spatial distribution of carbon sinks (Fan et al., 1998; Gurney et al., 2002; Yuen et al., 2005).”