Atmos. Chem. Phys. Discuss., 13, 2243-2271, 2013
www.atmos-chem-phys-discuss.net/13/2243/2013/
doi:10.5194/acpd-13-2243-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Improved simulation of group averaged CO2 surface concentrations using GEOS-Chem and fluxes from VEGAS
Z. H. Chen1, J. Zhu2, and N. Zeng3
1International Center for Climate and Environment Science, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
2State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
3Department of Meteorology and Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20742-2425, USA

Abstract. CO2 measurements have been combined with simulated CO2 distributions from a transport model in order to produce the optimal estimates of CO2 surface fluxes in inverse modeling. However one persistent problem in using model-observation comparisons for this goal relates to the issue of compatibility. Observations at a single site reflect all underlying processes of various scales that usually cannot be fully resolved by model simulations at the grid points nearest the site due to lack of spatial or temporal resolution or missing processes in models. In this article we group site observations of multiple stations according to atmospheric mixing regimes and surface characteristics. The group averaged values of CO2 concentration from model simulations and observations are used to evaluate the regional model results. Using the group averaged measurements of CO2 reduces the noise of individual stations. The difference of group averaged values between observation and modeled results reflects the uncertainties of the large scale flux in the region where the grouped stations are. We compared the group averaged values between model results with two biospheric fluxes from the model Carnegie-Ames-Stanford-Approach (CASA) and VEgetation-Global-Atmosphere-Soil (VEGAS) and observations to evaluate the regional model results. Results show that the modeling group averaged values of CO2 concentrations in all regions with fluxes from VEGAS have significant improvements for most regions. There is still large difference between two model results and observations for grouped average values in North Atlantic, Indian Ocean, and South Pacific Tropics. This implies possible large uncertainties in the fluxes there.

Citation: Chen, Z. H., Zhu, J., and Zeng, N.: Improved simulation of group averaged CO2 surface concentrations using GEOS-Chem and fluxes from VEGAS, Atmos. Chem. Phys. Discuss., 13, 2243-2271, doi:10.5194/acpd-13-2243-2013, 2013.
 
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