ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-8-7239-2008 Mechanisms for synoptic variations of atmospheric CO<sub>2</sub> in North America, South America and Europe Parazoo N. C. 1 Denning A. S. 1 Kawa S. R. 2 Corbin K. D. 1 Lokupitiya R. S. 1 Baker I. T. 1 Atmospheric Science Department, Colorado State University, Fort Collins, Colorado, USA NASA Goddard Space Flight Center, Greenbelt, Maryland, USA 10 12 2008 8 23 7239 7254 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/8/7239/2008/acp-8-7239-2008.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/8/7239/2008/acp-8-7239-2008.pdf

Synoptic variations of atmospheric CO<sub>2</sub> produced by interactions between weather and surface fluxes are investigated mechanistically and quantitatively in midlatitude and tropical regions using continuous in-situ CO<sub>2</sub> observations in North America, South America and Europe and forward chemical transport model simulations with the Parameterized Chemistry Transport Model. Frontal CO<sub>2</sub> climatologies show consistently strong, characteristic frontal CO<sub>2</sub> signals throughout the midlatitudes of North America and Europe. Transitions between synoptically identifiable CO<sub>2</sub> air masses or transient spikes along the frontal boundary typically characterize these signals. One case study of a summer cold front shows CO<sub>2</sub> gradients organizing with deformational flow along weather fronts, producing strong and spatially coherent variations. In order to differentiate physical and biological controls on synoptic variations in midlatitudes and a site in Amazonia, a boundary layer budget equation is constructed to break down boundary layer CO<sub>2</sub> tendencies into components driven by advection, moist convection, and surface fluxes. This analysis suggests that, in midlatitudes, advection is dominant throughout the year and responsible for 60–70% of day-to-day variations on average, with moist convection contributing less than 5%. At a site in Amazonia, vertical mixing, in particular coupling between convective transport and surface CO<sub>2</sub> flux, is most important, with advection responsible for 26% of variations, moist convection 32% and surface flux 42%. Transport model sensitivity experiments agree with budget analysis. These results imply the existence of a recharge-discharge mechanism in Amazonia important for controlling synoptic variations of boundary layer CO<sub>2</sub>, and that forward and inverse simulations should take care to represent moist convective transport. Due to the scarcity of tropical observations at the time of this study, results in Amazonia are not generalized for the tropics, and future work should extend analysis to additional tropical locations.

 References Andres, R. J., Marland, G., Fung, I., and Matthews, E.: A 1 degrees &times; 1 degrees distribution of carbon dioxide emissions from fossil fuel consumption and cement manufacture, 1950–1990, Global Biogeochem. Cy., 10, 419–429, 1996. Baker, I. T., Denning, A. S., Hanan, N., Prihodko, L., Vidale, P.-L., Davis, K., and Bakwin, P.: Simulated and observed fluxes of sensible and latent heat and CO<sub>2</sub> at the WLEF-TV Tower using SiB2.5, Global Change Biol., 9, 1262–1277, 2003. Baker, D. F., Law, R. M., Gurney, K. R., Rayner, P., et al.: TransCom 3 inversion intercomparison: Impact of transport model errors on the interannual variability of regional CO<sub>2</sub> fluxes, 1988–2003, Global Biogeochem. Cy., 20, GB1002, doi:10.1029/2004GB002439, 2006. Baker, I. T., Prihodko, L., Denning, S., Goulden, M., Miller, S., and Da Rocha, H. R.: Seasonal drought stress in the Amazon: Reconciling models and observations, J. Geophys. Res., 113, G00B01, doi:10.1029/2007JG000644, 2008. Bakwin, P. S., Tans, P. P., Hurst, D. F., and Zhao, C.: Measurements of carbon dioxide on very tall towers: results of the NOAA/CMDL program, Tellus, 50B, 401–415, 1998. Barford, C. C., Wofsy, S. C., Goulden, M. L., Munger, J. W., Pyle, E. H., et al.: Factors controlling long- and short-term sequestration of atmospheric CO<sub>2</sub> in a mid-latitude forest, Science, 294, 2415–2434, 2001. Biraud, S., Ciais, P., Ramonet, M., Simmonds, P., Kazan, V., Monfray, P., O'Doherty, S., Spain, G., and Jennings, S. G.: Quantification of carbon dioxide, methane, nitrous oxide and chloroform emissions over Ireland from atmospheric observations at Mace Head, Tellus, 54B, 41–60, 2002. Bloom, S., da Silva, A., and Dee, D.: Documentation and validation of the Goddard Earth Observing System (GEOS) Data Assimilation System, Version 4, Technical Report Series on Global Modeling and Data Assimilation, Greenbelt, MD, 2005. Chan, D., Yuen, C. W., Higuchi, K., Shashkov, A., Liu, J., Chen, J., and Worthy, D.: On the CO<sub>2</sub> exchange between the atmosphere and the biosphere: the role of synoptic and mesoscale processes, Tellus, 56B, 194–212, 2004. Corbin, K. D. and Denning, A. S.: Using continuous data to estimate clear-sky errors in inversion of satellite CO<sub>2</sub> measurements, Geophys. Res. Lett., 33, LI2810, doi:10.1029/2006GL025910, 2006. Dai, Y., Zeng, X., Dickinson, R. E., Baker, I., et al.: The common land model, Bull. Amer. Meteorol. Soc., 84, 1013–1023, 2003. Davis, K. J., Bakwin, P. S., Yi, C., Berger, B. W., Zhao, C., Teclaw, R. M., and Isebrands, J. G.: The annual cycle of CO<sub>2</sub> and H<sub>2</sub>O exchange over a northern mixed forest as observed from a very tall tower, Global Change Biol., 9, 1278–1293, 2003. Denning, A. S., Collatz, J. G., Zhang, C., Randall, D. A., Berry, J. A., Sellers, P. J., Colello, G. D., and Dazlich, D. A.: Simulations of terrestrial carbon metabolism and atmospheric CO<sub>2</sub> in a general circulation model – Part 1: Surface carbon fluxes, Tellus, 48B, 521–542, 1996. Eneroth, K., Aalto, T., Hatakka, J., Holmen, K., Laurila, T., and Viisanen, Y.: Atmospheric transport of carbon dioxide to a baseline monitoring station in northern Finland, Tellus, 57B, 366–374, 2005. Gamnitzer, U., Karstens, U., Kromer, B., Neubert, R. E. M., Meijer, H. A. J., Schroeder, H., and Levin, I.: Carbon monoxide: A quantitative tracer for fossil fuel CO<sub>2</sub>, J. Geophys. Res., 111, D22302, doi:10.1029/2005JD006966, 2006. Geels, C., Doney, S. C., Dargaville, R., Brandt, J., and Christensen, J. H.: Investigating the sources of synoptic variability in atmospheric CO<sub>2</sub> measurements over the Northern Hemisphere continents: a regional model study, Tellus, 56B, 35–50, 2004. Gerbig, C., Lin, J. C., Wofsy, S. C., Daube, B. C., Andrews, A. E., Stephens, B. B., Bakwin, P. S., and Grainger, C. A.: Toward constraining regional-scale fluxes of CO<sub>2</sub> with atmospheric observations over a continent: 2. Analysis of COBRA data using a receptor-oriented framework, J. Geophys. Res., 108(D24), 4757, doi:10.1029/2003JD003770, 2003. Goulden, M. L., Miller, S. D., da Rocha, H. R., Menton, M. C., de Freitas, H. C., e Silva Figueira, A. M., and de Sousa, C. A. D.: Diel and seasonal patterns of tropical forest CO<sub>2</sub> exchange, Ecol. Appl., 14(4), supplement, S42–S54, 2004. Gurney, K. R., Law, R. M., Denning, A. S., Rayner, P. J., et al.: Towards robust regional estimates of CO<sub>2</sub> sources and sinks using atmospheric transport models, Nature, 415, 626–630, 2002. Gurney, K. R., Law, R. M., Denning, A. S., Rayner, P. J., et al.: TransCom 3 CO<sub>2</sub> inversion intercomparison: 1. Annual mean control results and sensitivity to transport and prior flux informatin, Tellus, 55B, 555–579, 2003. Hack, J. J.: Parameterization of moist convection in the National Center for Atmospheric Research community climate model (CCM2), J. Geophys. Res., 99, 5551–5568, 1994. Hanan, N. P., Berry, J. A., Verma, S. B., Walter-Shea, E. A., Suyker, A. E., Burba, G. G., and Denning, A. S.: Testing a model of CO<sub>2</sub>, water and energy exchange in Great Plains tall-grass prairie and wheat ecosystems, Agr. Forest Meteorol., 131, 162–179, 2005. Haszpra, L., Barcza, Z., Bakwin, P. S., Berger, B. W., Davis, K. J., and Weidinger, T.: Measuring system for the long-term monitoring of biosphere/atmosphere exchange of carbon dioxide, J. Geophys. Res., 106D, 3057–3070, 2001. Hewson, T. D.: Objective fronts, Meteorol. Appl., 5, 37–65, 1998. Higuchi, K., Worthy, D., Chan, D., and Shashkov, A.: Regional source/sink impact on the diurnal, seasonal and inter-annual variations in atmospheric CO<sub>2</sub> at a boreal forest site in Canada, Tellus, 55B, 115–125, 2003. Holton, J. R.: An Introduction to Dynamic Meteorology, Third Edition, Elsevier, San Diego, CA, USA, 368–369, 267 pp., 1992. Huffman, G. J., Adler, R. F., Morrissey, M., Bolvin, D. T., Curtis, S., Joyce, R., McGavock, B., and Susskind, J.: Global precipitation at one degree daily resolution from multi-satellite observations, J. Hydrometeor., 2, 36–50, 2001. Kawa, S. R., Erickson III, D. J., Pawson, S., and Zhu, Z.: Global CO<sub>2</sub> transport simulations using meteorological data from the NASA data assimilation system, J. Geophys. Res., 109, D18312, doi:10.1029/2004JD004554, 2004. Kiehl, J. T., Hack, J. J., Bonan, G. B., Boville, B. A., Williamson, D. L., and Rasch, P. J.: The National Center for Atmospheric Research Community Climate Model: CCM3, J. Climate, 11, 1131–1149, 1998. Lauvaux, T., Uliasz, M., Sarrat, C., Chevallier, F., Bousquet, P., Lac, C., Davis, K. J., Ciais, P., Denning, A. S., and Rayner, P. J.: Mesoscale inversion: first results from the CERES campaign with synthetic data, Atmos. Chem. Phys., 8, 3459–3471, 2008. Law, R. M., Rayner, P. J., Steele, L. P., and Enting, I. G.: Using high temporal frequency data for CO<sub>2</sub> inversions, Global Biogeochem. Cy., 16(4), 1053, doi:10.1029/2001GB001593, 2002. Law, R. M., Peters, W., Rödenbeck, C., Aulagnier, C., et al.: TransCom model simulations of hourly atmospheric CO<sub>2</sub>: Experimental overview and diurnal cycle results for 2002, Global Biogeochem. Cy., 22, GB3009, doi:10.1029/2007GB003050, 2008. Lin, J. C., Gerbig, C., Wofsy, S. C., Andrews, A. E., Daube, B. C., Grainger, C. A., Stephens, B. B., Bakwin, P. S., and Hollinger, D. Y.: Measuring fluxes of trace gases at regional scales by Lagrangian observations: Application to the CO<sub>2</sub> Budget and Rectification Airborne (COBRA) study, J. Geophys. Res., 109, D15304, doi:10.1029/2004JD004754, 2004. Lin, S. J. and Rood, R. B.: Multidimensional flux-form semi-Lagrangian transport schemes, Mon. Weather Rev., 124, 2046–2070, 1996. McCann, D. W. and Whistler, J. P.: Problems and solutions for drawing fronts objectively, Meteorol. Appl., 8, 195–203, 2001. NOAA GMD Carbon Cycle Greenhouse Gases Group, online available at: http://www.esrl.noaa.gov/gmd/ccgg/index.html, March 2008. Patra, P. K., Law, R. M., Peters, W., Rödenbeck, C., et al.: TransCom model simulations of hourly atmospheric CO<sub>2</sub>: analysis of synoptic scale variations for the period 2002–2003, Global Biogeochem. Cy., 22, GB4013, doi:10.1029/2007GB003081, 2008. Peylin, P., Rayner, P. J., Bousquet, P., Carouge, C., Hourdin, F., Ciais, P., Heinrich, P., and AeroCarb Contributors: Daily CO<sub>2</sub> flux estimate over Europe from continuous atmospheric measurements: Part 1 inverse methodology, Atmos. Chem. Phys., 5, 3173–3186, 2005. Renard, R. J. and Clarke, L. C: Experiments in numerical objective frontal analysis, Mon. Weather Rev., 93, 547–556, 1965. Rödenbeck, C., Houweling, S., Gloor, M., and Heimann, M.: CO<sub>2</sub> flux history 1982–2001 inferred from atmospheric data using a global inversion of atmospheric transport, Atmos. Chem. Phys., 3, 1919–1964, 2003. Schultz, D. M.: A review of cold fronts with prefrontal troughs and wind shifts, Mon. Weather Rev., 133, 8, 2449–2472, 2005. Sellers, P. J., Mintz, Y., Sud, Y. C., and Dalcher, A.: A simple biosphere model (SiB) for use within general circulation models, J. Atmos. Sci., 43, 505–531, 1986. Sellers, P. J., Randall, D. A., Collatz, G. J., Berry, J. A., Field, C. B., Dazlich, D. A., Zhang, C., Collelo, G. D., and Bounoua, L.: A revised land-surface parameterization (SiB2) for atmospheric GCMs – Part 1: Model formulation, J. Climate, 1, 676–705, 1996. Sims, P. L. and Bradford, J. A.: Carbon dioxide fluxes in a southern plains prairie, Agr. Forest Meteorol., 109, 117–134, 2001. Stohl, A., Berg, T., Burkhart, J. F., Fjæraa, A. M., et al.: Arctic smoke – record high air pollution levels in the European Arctic due to agricultural fires in Eastern Europe in spring 2006, Atmos. Chem Phys., 7, 511–534, 2007. Syed, K. H., Flanagan, L. B., Carlson, P. J., Glenn, A. J., and Van Gaalen, K. E.: Environmental control of net ecosystem CO<sub>2</sub> exchange in a treed, moderately rich fen in northern Alberta, Agr. Forest Meteorol., 140, 97–114, 2006. Takahashi, T. S., Sutherland, S. C., Sweeney, C., Poisson, A., et al.: Global Sea-Air CO<sub>2</sub> flux based on climatological surface ocean pCO<sub>2</sub> and seasonal biological and temperature effects, Deep-Sea Research Part II, 49, 1601–1622, 2002. Vidale, P. L. and Stockli R.: Prognostic canopy air space solutions for land surface exchanges, Theor. Appl. Climatol., 80, 245–257, 2005. Wang, J.-W., Denning, A. S., Lu, L., Baker, I. T., Corbin, K. D., and Davis, K. J.: Observations and simulations of synoptic, regional, and local variations in atmospheric CO<sub>2</sub>, J. Geophys. Res., 112, D04108, doi:10.1029/2006JD007410, 2007. World Data Centre for Greenhouse Gases (WDCGG): http://gaw.kishou.go.jp/wdcgg/, June 2008. Worthy, D. E., Levin, I., Trivett, N. B., Kuhlmann, A. J., Hopper, J. F., and Ernst, M. K.: Seven years of continuous methane observations at a remote boreal site in Ontario, Canada, J. Geophys. Res., 103, D13, 15 995–16 007, 1998. Worthy, D. E., Higuchi, K., and Chan, D.: North American influence on atmospheric carbon dioxide data collected at Sable Island, Canada, Tellus, 55B, 105–114, 2003. Zhang, G. J. and McFarlane, N. A.: Sensitivity of climate simulations to the parameterizations of cumulus convection in the Canadian climate center general-circulation model, Atmos. Ocean, 33, 407–446, 1995.