The contribution of terrestrial sources and sinks to trends in the seasonal cycle of atmospheric carbon dioxide

Randerson, James T.; Thompson, Matthew V.; Conway, T. J.; Fung, Inez; Field, Christopher B.

doi:10.1029/97gb02268

Cited by 473 publications

(506 citation statements)

References 74 publications

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“…We estimate¯uxes for 11 land and 11 ocean regions (see Supplementary Information) as differences from`background'¯uxes that are run separately through each transport model and represent fossil-fuel emissions 17,18 , seasonally varying air±sea gas exchange 10 and an annually balanced, seasonally varying¯ux due to terrestrial photosynthesis and respiration 19 . The use of seasonally varying background¯uxes allows the annual mean inversion to include contributions to annual mean concentrations due to the covariance of atmospheric transport and seasonal¯uxes.…”

Section: Methodsmentioning

confidence: 99%

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

Gurney

Law

Denning

et al. 2002

Nature

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Section: Methodsmentioning

confidence: 99%

“…The inversion requires prior¯ux and uncertainty estimates. Our choices have been guided by ocean and terrestrial¯ux models and observations 10,19 , and are shown in Fig. 1 (also see Table 2 in Supplementary Information).…”

Section: Methodsmentioning

confidence: 99%

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

Gurney

Law

Denning

et al. 2002

Nature

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1,221

1,423

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“…Biosphere-atmosphere exchange in our simulations is based on monthly Carnegie Ames Stanford Approach (CASA) net ecosystem exchange (NEE) (Randerson et al, 1997). NEE represents the residual of monthly net primary production (NPP) and respiration fluxes that have been redistributed at 3 hour resolution based on 2001 climatology (Olsen and Randerson, 2004).…”

Section: Methodsmentioning

confidence: 99%

Sources of variations in total column carbon dioxide

2011

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Abstract.Observations of gradients in the total CO 2 column, CO 2 , are expected to provide improved constraints on surface fluxes of CO 2 . Here we use a general circulation model with a variety of prescribed carbon fluxes to investigate how variations in CO 2 arise. On diurnal scales, variations are small and are forced by both local fluxes and advection. On seasonal scales, gradients are set by the north-south flux distribution. On synoptic scales, variations arise due to large-scale eddy-driven disturbances of the meridional gradient. In this case, because variations in CO 2 are tied to synoptic activity, significant correlations exist between CO 2 and dynamical tracers. We illustrate how such correlations can be used to describe the north-south gradients of CO 2 and the underlying fluxes on continental scales. These simulations suggest a novel analysis framework for using column observations in carbon cycle science.

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“…CASA 0 CASA 0 is derived from the off-line land biogeochemistry model CASA (Potter et al, 1993;Randerson et al, 1997) and tracks the flow of carbon through live vegetation, litter, and soil organic matter pools. A primary difference between the two models is that CASA estimates monthly NPP from satellite observations of the fraction of absorbed photosynthetically active radiation (fAPAR), while CASA 0 assumes NPP is 50% of the instantaneous GPP calculated from CLM.…”

Section: Model Descriptionmentioning

confidence: 99%

Systematic assessment of terrestrial biogeochemistry in coupled climate–carbon models

Randerson

Hoffman

Thornton

et al. 2009

Global Change Biology

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With representation of the global carbon cycle becoming increasingly complex in climate models, it is important to develop ways to quantitatively evaluate model performance against in situ and remote sensing observations. Here we present a systematic framework, the Carbon‐LAnd Model Intercomparison Project (C‐LAMP), for assessing terrestrial biogeochemistry models coupled to climate models using observations that span a wide range of temporal and spatial scales. As an example of the value of such comparisons, we used this framework to evaluate two biogeochemistry models that are integrated within the Community Climate System Model (CCSM) – Carnegie‐Ames‐Stanford Approach′ (CASA′) and carbon–nitrogen (CN). Both models underestimated the magnitude of net carbon uptake during the growing season in temperate and boreal forest ecosystems, based on comparison with atmospheric CO2 measurements and eddy covariance measurements of net ecosystem exchange. Comparison with MODerate Resolution Imaging Spectroradiometer (MODIS) measurements show that this low bias in model fluxes was caused, at least in part, by 1–3 month delays in the timing of maximum leaf area. In the tropics, the models overestimated carbon storage in woody biomass based on comparison with datasets from the Amazon. Reducing this model bias will probably weaken the sensitivity of terrestrial carbon fluxes to both atmospheric CO2 and climate. Global carbon sinks during the 1990s differed by a factor of two (2.4 Pg C yr−1 for CASA′ vs. 1.2 Pg C yr−1 for CN), with fluxes from both models compatible with the atmospheric budget given uncertainties in other terms. The models captured some of the timing of interannual global terrestrial carbon exchange during 1988–2004 based on comparison with atmospheric inversion results from TRANSCOM (r=0.66 for CASA′ and r=0.73 for CN). Adding (CASA′) or improving (CN) the representation of deforestation fires may further increase agreement with the atmospheric record. Information from C‐LAMP has enhanced model performance within CCSM and serves as a benchmark for future development. We propose that an open source, community‐wide platform for model‐data intercomparison is needed to speed model development and to strengthen ties between modeling and measurement communities. Important next steps include the design and analysis of land use change simulations (in both uncoupled and coupled modes), and the entrainment of additional ecological and earth system observations. Model results from C‐LAMP are publicly available on the Earth System Grid.

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The contribution of terrestrial sources and sinks to trends in the seasonal cycle of atmospheric carbon dioxide

Cited by 473 publications

References 74 publications

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

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

Sources of variations in total column carbon dioxide

Systematic assessment of terrestrial biogeochemistry in coupled climate–carbon models

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