ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-8-1209-2008 Basin-scale wind transport during the MILAGRO field campaign and comparison to climatology using cluster analysis de Foy B. 1 2 Fast J. D. 3 Paech S. J. 4 Phillips D. 4 Walters J. T. 4 Coulter R. L. 5 Martin T. J. 5 Pekour M. S. 3 Shaw W. J. 3 Kastendeuch P. P. 6 Marley N. A. 7 Retama A. 8 Molina L. T. 1 9 Molina Center for Energy and the Environment, CA, USA Department of Earth and Atmospheric Sciences, Saint Louis University, USA Pacific Northwest National Laboratory, Richland, WA, USA National Space Science and Technology Center, University of Alabama in Huntsville, AL, USA Argonne National Laboratory, IL, USA Centre de Géochimie de la Surface, Université Louis Pasteur, Strasbourg, France Department of Chemistry, University of Arkansas at Little Rock, AK, USA Secretaría del Medio Ambiente, Gobierno del Distrito Federal, México Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, USA 03 03 2008 8 5 1209 1224 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/8/1209/2008/acp-8-1209-2008.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/8/1209/2008/acp-8-1209-2008.pdf

The MILAGRO field campaign was a multi-agency international collaborative project to evaluate the regional impacts of the Mexico City air pollution plume as a means of understanding urban impacts on the global climate. Mexico City lies on an elevated plateau with mountains on three sides and has complex mountain and surface-driven wind flows. This paper asks what the wind transport was in the basin during the field campaign and how representative it was of the climatology. Surface meteorology and air quality data, radiosondes and radar wind profiler data were collected at sites in the basin and its vicinity. Cluster analysis was used to identify the dominant wind patterns both during the campaign and within the past 10 years of operational data from the warm dry season. Our analysis shows that March 2006 was representative of typical flow patterns experienced in the basin. Six episode types were identified for the basin-scale circulation providing a way of interpreting atmospheric chemistry and particulate data collected during the campaign. Decoupling between surface winds and those aloft had a strong influence in leading to convection and poor air quality episodes. Hourly characterisation of wind circulation during the MILAGRO, MCMA-2003 and IMADA field campaigns enables the comparisons of similar air pollution episodes and the evaluation of the impact of wind transport on measurements of the atmospheric chemistry taking place in the basin.

 References Banta, R M., Darby, L S., Fast, J D., Pinto, J O., Whiteman, C D., Shaw, W J., and Orr, B W.: Nocturnal low-level jet in a mountain basin complex. part I: Evolution and effects on local flows, J. Appl. Meteorol., 43, 1348–1365, 2004. Beaver, S. and Palazoglu, A.: Cluster analysis of hourly wind measurements to reveal synoptic regimes affecting air quality, J. Appl. Meteorol. Climatol., 45, 1710–1726, 2006. Bossert, J E.: An investigation of flow regimes affecting the Mexico City region, J. Appl. Meteorol., 36, 119–140, 1997. Case, J L., Manobianco, J., Lane, J E., Immer, C D., and Merceret, F J.: An objective technique for verifying sea breezes in high-resolution numerical weather prediction models, Weather Forecast., 19, 690–705, 2004. Case, J L., Wheeler, M M., Manobianco, J., Weems, J W., and Roeder, W P.: A 7-yr climatological study of land breezes over the Florida spaceport, J. Appl. Meteorol., 44, 340–356, 2005. Cooper, D I. and Eichinger, W E.: Structure of the atmosphere in an urban planetary boundary layer from lidar and radiosonde observations, J. Geophys. Res., 99, 22 937–22 948, 1994. Darby, L S.: Cluster analysis of surface winds in Houston, Texas, and the impact of wind patterns on ozone, J. Appl. Meteorol., 44, 1788–1806, 2005. Davis, J M., Eder, B K., Nychka, D., and Yang, Q.: Modeling the effects of meteorology on ozone in Houston using cluster analysis and generalized additive models, Atmos. Environ., 32, 2505–2520, 1998. Davis, R E. and Walker, D R.: An upper-air synoptic climatology of the western united-states, J. Climate, 5, 1449–1467, 1992. de~Foy, B., Caetano, E., Magaña, V., Zitácuaro, A., Cárdenas, B., Retama, A., Ramos, R., Molina, L T., and Molina, M J.: Mexico City basin wind circulation during the MCMA-2003 field campaign, Atmos. Chem. Phys., 5, 2267–2288, 2005. de~Foy, B., Clappier, A., Molina, L T., and Molina, M J.: Distinct wind convergence patterns in the Mexico City basin due to the interaction of the gap winds with the synoptic flow, Atmos. Chem. Phys., 6, 1249–1265, 2006a. de~Foy, B., Varela, J R., Molina, L T., and Molina, M J.: Rapid ventilation of the Mexico City basin and regional fate of the urban plume, Atmos. Chem. Phys., 6, 2321–2335, 2006b. Doran, J C. and Zhong, S.: Thermally driven gap winds into the Mexico City basin, J. Appl. Meteorol., 39, 1330–1340, 2000. Doran, J C., Abbott, S., Archuleta, J., Bian, X., Chow, J., Coulter, R L., de~Wekker, S. F J., Edgerton, S., Elliott, S., Fernandez, A., Fast, J D., Hubbe, J M., King, C., Langley, D., Leach, J., Lee, J T., Martin, T J., Martinez, D., Martinez, J L., Mercado, G., Mora, V., Mulhearn, M., Pena, J L., Petty, R., Porch, W., Russell, C., Salas, R., Shannon, J D., Shaw, W J., Sosa, G., Tellier, L., Templeman, B., Watson, J G., White, R., Whiteman, C D., and Wolfe, D.: The IMADA-AVER boundary layer experiment in the Mexico City area, B. Am. Meteor. Soc., 79, 2497–2508, 1998. Doran, J C., Barnard, J C., Arnott, W P., Cary, R., Coulter, R., Fast, J D., Kassianov, E I., Kleinman, L., Laulainen, N S., Martin, T., Paredes-Miranda, G., Pekour, M S., Shaw, W J., Smith, D F., Springston, S R., and Yu, X Y.: The T1-T2 study: evolution of aerosol properties downwind of Mexico City, Atmos. Chem. Phys., 7, 1585–1598, 2007. Egger, J., Blacutt, L., Ghezzi, F., Heinrich, R., Kolb, P., Lammlein, S., Leeb, M., Mayer, S., Palenque, E., Reuder, J., Schaper, W., Schween, J., Torrez, R., and Zaratti, F.: Diurnal circulation of the Bolivian Altiplano. Part I: Observations, Mon. Weather Rev., 133, 911–924, 2005. Fast, J D. and Zhong, S Y.: Meteorological factors associated with inhomogeneous ozone concentrations within the Mexico City basin, J. Geophys. Res.-Atmos., 103, 18 927–18 946, 1998. Fast, J D., de~Foy, B., Rosas, F A., Caetano, E., Carmichael, G., Emmons, L., McKenna, D., Mena, M., Skamarock, W., Tie, X., Coulter, R L., Barnard, J C., Wiedinmyer, C., and Madronich, S.: A meteorological overview of the MILAGRO field campaigns, Atmos. Chem. Phys., 7, 2233–2257, 2007. Hart, M., Dear, R D., and Hyde, R.: A synoptic climatology of tropospheric ozone episodes in Sydney, Australia, Int. J. Climatol., 26, 1635–1649, 2006. Jauregui, E.: Local wind and air pollution interaction in the Mexico basin, Atmosfera, 1, 131–140, 1988. Jazcilevich, A D., Garcia, A R., and Caetano, E.: Locally induced surface air confluence by complex terrain and its effects on air pollution in the valley of Mexico, Atmos. Environ., 39, 5481–5489, 2005. Kastendeuch, P P. and Kaufmann, P.: Classification of summer wind fields over complex terrain, Int. J. Climatol., 17, 521–534, 1997. Kastendeuch, P P. and Najjar, G.: Upper-air wind profiles investigation for tropospheric circulation study, Theoretical Applied Climatology, 75, 149–165, 2003. Kaufmann, P. and Weber, R O.: Classification of mesoscale wind fields in the MISTRAL field experiment, J. Appl. Meteorol., 35, 1963–1979, 1996. Kaufmann, P. and Whiteman, C D.: Cluster-analysis classification of wintertime wind patterns in the Grand Canyon region, J. Appl. Meteorol., 38, 1131–1147, 1999. Klaus, D., Poth, A., Voss, M., and Jauregui, E.: Ozone distributions in Mexico City using principal component analysis and its relation to meteorological parameters, Atmosfera, 14, 171–188, 2001. Kolb, C E., Herndon, S C., McManus, B., Shorter, J H., Zahniser, M S., Nelson, D D., Jayne, J T., Canagaratna, M R., and Worsnop, D R.: Mobile laboratory with rapid response instruments for real-time measurements of urban and regional trace gas and particulate distributions and emission source characteristics, Environ. Sci. Technol., 38, 5694–5703, 2004. Kossmann, M., Sturman, A P., Zawar-Reza, P., McGowan, H A., Oliphant, A J., Owens, I F., and Spronken-Smith, R A.: Analysis of the wind field and heat budget in an alpine lake basin during summertime fair weather conditions, Meteorol. Atmos. Phys., 81, 27–52, 2002. Lemonsu, A., Bastin, S., Masson, V., and Drobinski, P.: Vertical structure of the urban boundary layer over Marseille under sea-breeze conditions, Bound.-Lay. Meteorol., 118, 477–501, 2006. Lu, H C., Chang, C L., and Hsieh, J C.: Classification of PM10 distributions in Taiwan, Atmos. Environ., 40, 1452–1463, 2006. Mayr, G J., Armi, L., Arnold, S., Banta, R M., Darby, L S., Durran, D D., Flamant, C., Gabersek, S., Gohm, A., Mayr, R., Mobbs, S., Nance, L B., Vergeiner, I., Vergeiner, J., and Whiteman, C D.: Gap flow measurements during the Mesoscale Alpine Programme, Meteorol. Atmos. Phys., 86, 99–119, 2004. Molina, L T., Kolb, C E., de~Foy, B., Lamb, B K., Brune, W H., Jimenez, J L., Ramos-Villegas, R., Sarmiento, J., Paramo-Figueroa, V H., Cardenas, B., Gutierrez-Avedoy, V., and Molina, M J.: Air quality in North America's most populous city – overview of the MCMA-2003 campaign, Atmos. Chem. Phys., 7, 2447–2473, 2007. Oanh, N. T K., Chutimon, P., Ekbordin, W., and Supat, W.: Meteorological pattern classification and application for forecasting air pollution episode potential in a mountain-valley area, Atmos. Environ., 39, 1211–1225, 2005. Raga, G B., Baumgardner, D., Kok, G., and Rosas, I.: Some aspects of boundary layer evolution in Mexico City, Atmos. Environ., 33, 5013–5021, 1999. Regmi, R P., Kitada, T., and Kurata, G.: Numerical simulation of late wintertime local flows in Kathmandu valley, Nepal: Implication for air pollution transport, J. Appl. Meteorol., 42, 389–403, 2003. Turias, I J., Gonzalez, F J., Martin, M L., and Galindo, P L.: A competitive neural network approach for meteorological situation clustering, Atmos. Environ., 40, 532–541, 2006. Weber, R O. and Furger, M.: Climatology of near-surface wind patterns over Switzerland, Int. J. Climatol., 21, 809–827, 2001. Weber, R O. and Kaufmann, P.: Automated classification scheme for wind fields, J. Appl. Meteorol., 34, 1133–1141, 1995. Whiteman, C D., Zhong, S., Bian, X., Fast, J D., and Doran, J C.: Boundary layer evolution and regional-scale diurnal circulations over the Mexico Basin and Mexican Plateau, J. Geophys. Res.-Atmos., 105, 10 081–10 102, 2000.