ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-12-2441-2012 Error characterization of CO<sub>2</sub> vertical mixing in the atmospheric transport model WRF-VPRM Kretschmer R. 1 Gerbig C. 1 Karstens U. 1 Koch F.-T. 1 Max Planck Institute for Biogeochemistry, Jena, Germany 05 03 2012 12 5 2441 2458 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/12/2441/2012/acp-12-2441-2012.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/12/2441/2012/acp-12-2441-2012.pdf

One of the dominant uncertainties in inverse estimates of regional CO<sub>2</sub> surface-atmosphere fluxes is related to model errors in vertical transport within the planetary boundary layer (PBL). In this study we present the results from a synthetic experiment using the atmospheric model WRF-VPRM to realistically simulate transport of CO<sub>2</sub> for large parts of the European continent at 10 km spatial resolution. To elucidate the impact of vertical mixing error on modeled CO<sub>2</sub> mixing ratios we simulated a month during the growing season (August 2006) with different commonly used parameterizations of the PBL (Mellor-Yamada-Janjić (MYJ) and Yonsei-University (YSU) scheme). To isolate the effect of transport errors we prescribed the same CO<sub>2</sub> surface fluxes for both simulations. Differences in simulated CO<sub>2</sub> mixing ratios (model bias) were on the order of 3 ppm during daytime with larger values at night. We present a simple method to reduce this bias by 70–80% when the true height of the mixed layer is known.

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