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Article Dans Une Revue Journal of Geophysical Research: Atmospheres Année : 2011

The seasonal cycle amplitude of total column CO 2 : Factors behind the model-observation mismatch

Résumé

[1] CO 2 surface fluxes that are statistically consistent with surface layer measurements of CO 2 , when propagated forward in time by atmospheric transport models, underestimate the seasonal cycle amplitude of total column CO 2 in the northern temperate latitudes by 1-2 ppm. In this paper we verify the systematic nature of this underestimation at a number of Total Carbon Column Observation Network (TCCON) stations by comparing their measurements with a number of transport models. In particular, at Park Falls, Wisconsin (United States), we estimate this mismatch to be 1.4 ppm and try to attribute portions of this mismatch to different factors affecting the total column. We find that errors due to (1) the averaging kernel and prior profile used in forward models, (2) water vapor in the model atmosphere, (3) incorrect vertical transport by transport models in the free troposphere, (4) incorrect aging of air in transport models in the stratosphere, and (5) air mass dependence in TCCON data can explain up to 1 ppm of this mismatch. The remaining 0.4 ppm mismatch is at the edge of the ≤0.4 ppm accuracy requirement on satellite measurements to improve on our current estimate of surface fluxes. Uncertainties in the biosphere fluxes driving the transport models could explain a part of the remaining 0.4 ppm mismatch, implying that with corrections to the factors behind the accounted-for 1 ppm underestimation, present inverse modeling frameworks could effectively assimilate satellite CO 2 measurements.
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Dates et versions

hal-02951880 , version 1 (07-10-2020)

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Sourish Basu, Sander Houweling, Wouter Peters, Colm Sweeney, Toshinobu Machida, et al.. The seasonal cycle amplitude of total column CO 2 : Factors behind the model-observation mismatch. Journal of Geophysical Research: Atmospheres, 2011, 116 (D23), pp.n/a-n/a. ⟨10.1029/2011JD016124⟩. ⟨hal-02951880⟩
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