ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-6349-2011 Tropospheric ozone production related to West African city emissions during the 2006 wet season AMMA campaign Ancellet G. 1 Orlandi E. 2 Real E. 1 Law K. S. 1 Schlager H. 3 Fierli F. 2 Nielsen J. K. 4 Thouret V. 5 Mari C. 5 UPMC Univ. Paris 06, UMR8190, CNRS/INSU, LATMOS-IPSL – Université Versailles, St-Quentin, France ISAC-Institute for Atmospheric Sciences and Climate, National Research Council, Bologna, Italy DLR Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany Danish Meteorological Institute, Lyngbyvej, Denmark Université de Toulouse, CNRS, LA (Laboratoire d'Aérologie), Toulouse, France 05 07 2011 11 13 6349 6366 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/11/6349/2011/acp-11-6349-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/6349/2011/acp-11-6349-2011.pdf

During African Monsoon Multidisciplinary Analyses (AMMA) airborne measurements of ozone, CO and nitrogen oxides (NO<sub>x</sub>) were collected by French and German Falcon aircraft near three cities in West Africa (Cotonou, Niamey and Ouagadougou). They have been analysed to identify the good conditions to observe ozone plumes related to city emissions during the monsoon season. Results show that an O<sub>3</sub> increase of 40–50 ppbv above the summer average concentration took place during two specific events: one near Cotonou on the coast of the Gulf of Guinea, and the other near Niamey in the Sahel region. In both cases a high level of NO<sub>x</sub> (3–5 ppbv) is related to the ozone production. Air mass transport simulations with FLEXPART and a tracer simulation with the BOLAM mesoscale model shows that Southern Hemisphere biomass burning emissions are always at higher altitude (>3 km) compared to the city emissions. In Niamey and Ouagadougou, the daily variability of ozone and CO correlates with the FLEXPART analysis showing the role of air mass stagnation near the city for 1–2 days and advection of emissions from the vegetated areas. Absence of ozone enhancements for high CO values can be explained by the occurrence of deep convection near the city. In the Sahel region, convection must be accounted for to understand the small number of observed ozone plumes but also to explain the high level of NO<sub>x</sub> in the 3–5 ppbv range, due to increasing soil emissions after rainfall. To verify that daily ozone production can reach 20 ppbv day<sup>−1</sup> for the NO<sub>x</sub> and CO conditions encountered near West African cities, a simulation of the CiTTyCAT Lagrangian model was conducted using the observed average chemical composition reported by other aircraft during AMMA. Such ozone production is possible for NO<sub>x</sub> levels up to 5 ppb showing that West African cities are potentially significant sources of tropospheric ozone.

 References Aghedo, A. M., Schultz, M. G., and Rast, S.: The influence of African air pollution on regional and global tropospheric ozone, Atmos. Chem. Phys., 7, 1193–1212, http://dx.doi.org/10.5194/acp-7-1193-2007doi:10.5194/acp-7-1193-2007, 2007. Agusti-Panareda, A., Beljaars, A., Genkova, I., Cardinali, C., and Thorncroft, C.: Impact of assimilating AMMA soundings on ECMWF analyses and forecasts, Tech rep., ECMWF Technical Memorandum, 2009. Ancellet, G., Leclair de Bellevue, J., Mari, C., Nedelec, P., Kukui, A., Borbon, A., and Perros, P.: Effects of regional-scale and convective transports on tropospheric ozone chemistry revealed by aircraft observations during the wet season of the AMMA campaign, Atmos. Chem. Phys., 9, 383–411, http://dx.doi.org/10.5194/acp-9-383-2009doi:10.5194/acp-9-383-2009, 2009. Andreae, M. and Merlet, P.: Emission of Trace Gases and Aerosols From Biomass Burning, Global Biogeochem. Cy., 15, 955–966, http://dx.doi.org/10.1029/2000GB001382doi:10.1029/2000GB001382, 2001. Baehr, J., Schlager, H., Ziereis, H., Stock, P., Velthoven, P V., Busen, R., Ström, J., and Schumann, U.: Aircraft observations of NO, \NOy CO, and \Ot in the upper troposphere from 60\dg N to 60\dg S – Interhemispheric differences at mitlatitudes, Geophys. Res. Lett., 30, 1598–1601, http://dx.doi.org/10.1029/2003GL016935doi:10.1029/2003GL016935, 2003. Baumbach, G., Vogt, U., Hein, K. R G., Oluwole, A F., Ogunsola, O J., Olaniyi, H B., and Akeredolu, F A.: Air pollution in a large tropical city with a high traffic density – results of measurements in Lagos, Nigeria, Sci. Total Environ., 169, 25–31, http://dx.doi.org/10.1016/0048-9697(95)04629-Fdoi:10.1016/0048-9697(95)04629-F, 1995. Chatfield, R. and Delany, A.: Convection Links Biomass Burning to Increased Tropical Ozone: However, Models Will Tend to Overpredict \Ot, J. Geophys. Res., 95, 18473–18488, http://dx.doi.org/10.1029/JD095iD11p18473doi:10.1029/JD095iD11p18473, 1990. Colette, A. and Ancellet, G.: Variability of the tropospheric mixing and of streamer formation and their impact on the lifetime of observed ozone layers, Geophys. Res. Lett., 33, L09808, http://dx.doi.org/10.1029/2006GL025793doi:10.1029/2006GL025793, 2006. Delon, C., Reeves, C. E., Stewart, D. J., Serça, D., Dupont, R., Mari, C., Chaboureau, J.-P., and Tulet, P.: Biogenic nitrogen oxide emissions from soils - impact on NO<sub>x</sub> and ozone over West Africa during AMMA (African Monsoon Multidisciplinary Experiment): modelling study, Atmos. Chem. Phys., 8, 2351–2363, http://dx.doi.org/10.5194/acp-8-2351-2008doi:10.5194/acp-8-2351-2008, 2008. Derognat, C., Beekmann, M., Baeumle, M., Martin, D., and Schmidt, H.: Effect of biogenic volatile organic compound emissions on tropospheric chemistry during the Atmospheric Pollution Over the Paris Area (ESQUIF) campaign in the Ile-de-France region, J. Geophys. Res., 108, 8560–8574, http://dx.doi.org/10.1029/2001JD001421doi:10.1029/2001JD001421, 2003. Evans, M J., Shallcross, D E., Law, K S., Wild, J O F., Simmonds, P G., Spain, T G., Berrisford, P., Methven, J., Lewis, A C., McQuaid, J B., Pillinge, M J., Bandyf, B J., Penkett, S A., and Pyle, J A.: Evaluation of a Lagrangian box model using field measurements from EASE (Eastern Atlantic Summer Experiment) 1996, Atmos. Environ., 34, 3843–3863, http://dx.doi.org/10.1016/S1352-2310(00)00184-9doi:10.1016/S1352-2310(00)00184-9, 2000. Grant, D D., Fuentes, J D., DeLonge, M S., Chan, S., Joseph, E., Kucera, P., Ndiaye, S A., and Gaye, A T.: Ozone transport by mesoscale convective storms in western Senegal, Atmos. Environ., 42, 7104–7114, http://dx.doi.org/10.1016/j.atmosenv.2008.05.044doi:10.1016/j.atmosenv.2008.05.044, 2008. Guenther, A., Karl, T., Harley, P., Wiedinmyer, C., Palmer, P. I., and Geron, C.: Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature), Atmos. Chem. Phys., 6, 3181–3210, http://dx.doi.org/10.5194/acp-6-3181-2006doi:10.5194/acp-6-3181-2006, 2006. Hopkins, J. R., Evans, M. J., Lee, J. D., Lewis, A. C., H Marsham, J., McQuaid, J. B., Parker, D. J., Stewart, D. J., Reeves, C. E., and Purvis, R. M.: Direct estimates of emissions from the megacity of Lagos, Atmos. Chem. Phys., 9, 8471–8477, http://dx.doi.org/10.5194/acp-9-8471-2009doi:10.5194/acp-9-8471-2009, 2009. Huntrieser, H., Schumann, U., Schlager, H., Höller, H., Giez, A., Betz, H.-D., Brunner, D., Forster, C., Pinto Jr., O., and Calheiros, R.: Lightning activity i n Brazilian thunderstorms during TROCCINOX: implications for NO<sub>x</sub> production, Atmos. Chem. Phys., 8, 921–953, http://dx.doi.org/10.5194/acp-8-921-2008doi:10.5194/acp-8-921-2008, 2008. Kain, J S.: The Kain-Fritsch Convective Parameterization: An Update, J. Appl. Meteorol., 43, 170–181, http://dx.doi.org/10.1175/1520-0450(2004)043<0170:TKCPAU>2.0.CO;2doi:10.1175/1520-0450(2004)043<0170:TKCPAU>2.0.CO;2, 2004. Liao, H., Yung, Y L., and Seinfield, J H.: Effect of aerosol on tropospheric photolysis rates in clear and cloudy atmospheres, J. Geophys. Res., 104, 23697–23707, http://dx.doi.org/10.1029/1999JD900409doi:10.1029/1999JD900409, 1999. Liousse, C., Guillaume, B., Grégoire, J. M., Mallet, M., Galy, C., Pont, V., Akpo, A., Bedou, M., Castéra, P., Dungall, L., Gardrat, E., Granier, C., Konaré, A., Malavelle, F., Mariscal, A., Mieville, A., Rosset, R., Serça, D., Solmon, F., Tummon, F., Assamoi, E., Yoboué, V., and Van Velthoven, P.: Updated African biomass burning emission inventories in the framework of the AMMA-IDAF program, with an evaluation of combustion aerosols, Atmos. Chem. Phys., 10, 9631–9646, http://dx.doi.org/10.5194/acp-10-9631-2010doi:10.5194/acp-10-9631-2010, 2010. Malguzzi, P., Grossi, G., Buzzi, A., Ranzi, R., and Buizza, R.: The 1966 "century" flood in Italy: A meteorological and hydrological revisitation, J. Geophys. Res., 111, D24106, http://dx.doi.org/10.1029/2006JD007111doi:10.1029/2006JD007111, 2006. Mari, C. H., Cailley, G., Corre, L., Saunois, M., Attié, J. L., Thouret, V., and Stohl, A.: Tracing biomass burning plumes from the Southern Hemisphere during the AMMA~2006 wet season experiment, Atmos. Chem. Phys., 8, 3951–3961, http://dx.doi.org/10.5194/acp-8-3951-2008doi:10.5194/acp-8-3951-2008, 2008. Mauzerall, D L., Logan, J A., Jacob, D J., Anderson, B E., Blake, D R., Bradshaw, J D., Haikes, B., Sachse, G W., Singh, H., and Talbot, B.: Photochemistry in biomass burning plumes and implications for tropospheric ozone over the tropical South Atlantic, J. Geophys. Res., 103, 8401–8423, http://dx.doi.org/10.1029/97JD02612doi:10.1029/97JD02612, 1998. Minga, A., Thouret, V., Saunois, M., Delon, C., Serça, D., Mari, C., Sauvage, B., Mariscal, A., Leriche, M., and Cros, B.: What caused extreme ozone concentrations over Cotonou in December 2005?, Atmos. Chem. Phys., 10, 895–907, http://dx.doi.org/10.5194/acp-10-895-2010doi:10.5194/acp-10-895-2010, 2010. Parker, D., Burton, R., Diongue-Niang, A., Ellis, R., Felton, M., Taylor, C., Thorncroft, C., Bessemoulin, P., and Tompkins, A.: The diurnal cycle of the West African monsoon circulation, Q. J. Roy. Meteorol. Soc., 131, 2839–2860, http://dx.doi.org/10.1256/qj.04.52doi:10.1256/qj.04.52, 2005. Real, E., Orlandi, E., Law, K. S., Fierli, F., Josset, D., Cairo, F., Schlager, H., Borrmann, S., Kunkel, D., Volk, C. M., McQuaid, J. B., Stewart, D. J., Lee, J., Lewis, A. C., Hopkins, J. R., Ravegnani, F., Ulanovski, A., and Liousse, C.: Cross-hemispheric transport of central African biomass burning pollutants: implications for downwind ozone production, Atmos. Chem. Phys., 10, 3027–3046, http://dx.doi.org/10.5194/acp-10-3027-2010doi:10.5194/acp-10-3027-2010, 2010. Reeves, C. E., Formenti, P., Afif, C., Ancellet, G., Attié, J.-L., Bechara, J., Borbon, A., Cairo, F., Coe, H., Crumeyrolle, S., Fierli, F., Flamant, C., Gomes, L., Hamburger, T., Jambert, C., Law, K. S., Mari, C., Jones, R. L., Matsuki, A., Mead, M. I., Methven, J., Mills, G. P., Minikin, A., Murphy, J. G., Nielsen, J. K., Oram, D. E., Parker, D. J., Richter, A., Schlager, H., Schwarzenboeck, A., and Thouret, V.: Chemical and aerosol characterisation of the troposphere over West Africa during the monsoon period as part of AMMA, Atmos. Chem. Phys., 10, 7575–7601, http://dx.doi.org/10.5194/acp-10-7575-2010doi:10.5194/acp-10-7575-2010, 2010. Sanderson, M G., Dentener, F J., Fiore, A M., Cuvelier, C., Keating, T J., Zuber, A., Atherton, C S., Bergmann, D J., Diehl, T., Doherty, R M., Duncan, B N., Hess, P., Horowitz, L W., Jacob, D J., Jonson, J.-E., Kaminski, J W., Lupu, A., MacKenzie, I A., Mancini, E., Marmer, E., Park, R., Pitari, G., Prather, M J., Pringle, K J., Schroeder, S., Schultz, M G., Shindell, D T., Szopa, S., Wild, O., and Wind, P.: A multi-model study of the hemispheric transport and deposition of oxidised nitrogen, Geophys. Res. Lett., 35, L17815, http://dx.doi.org/10.1029/2008GL035389doi:10.1029/2008GL035389, 2008. Saunois, M., Reeves, C. E., Mari, C. H., Murphy, J. G., Stewart, D. J., Mills, G. P., Oram, D. E., and Purvis, R. M.: Factors controlling the distribution of ozone in the West African lower troposphere during the AMMA (African Monsoon Multidisciplinary Analysis) wet season campaign, Atmos. Chem. Phys., 9, 6135–6155, http://dx.doi.org/10.5194/acp-9-6135-2009doi:10.5194/acp-9-6135-2009, 2009. Sauvage, B., Gheusi, F., Thouret, V., Cammas, J.-P., Duron, J., Escobar, J., Mari, C., Mascart, P., and Pont, V.: Medium-range mid-tropospheric transport of ozone and precursors over Africa: two numerical case studies in dry and wet seasons, Atmos. Chem. Phys., 7, 5357–5370, http://dx.doi.org/10.5194/acp-7-5357-2007doi:10.5194/acp-7-5357-2007, 2007a. Sauvage, B., Martin, R., van Donkelaar, A., and Ziemke, J.: Quantification of the factors controlling tropical tropospheric ozone and the South Atlantic maximum, J. Geophys. Res., 112, D11309–D11322, http://dx.doi.org/10.1029/2006JD008008doi:10.1029/2006JD008008, 2007b. Schultz, P.: An Explicit Cloud Physics Parameterization for Operational Numerical Weather Prediction, Mon. Weather Rev., 123, 3331–3343, http://dx.doi.org/10.1175/1520-0493(1995)123<3331:AECPPF>2.0.CO;2doi:10.1175/1520-0493(1995)123<3331:AECPPF>2.0.CO;2, 1995. Schumann, U. and Huntrieser, H.: The global lightning-induced nitrogen oxides source, Atmos. Chem. Phys., 7, 3823–3907, http://dx.doi.org/10.5194/acp-7-3823-2007doi:10.5194/acp-7-3823-2007, 2007. Stewart, D. J., Taylor, C. M., Reeves, C. E., and McQuaid, J. B.: Biogenic nitrogen oxide emissions from soils: impact on NO<sub>x</sub> and ozone over west Africa during AMMA (African Monsoon Multidisciplinary Analysis): observational study, Atmos. Chem. Phys., 8, 2285–2297, http://dx.doi.org/10.5194/acp-8-2285-2008doi:10.5194/acp-8-2285-2008, 2008. Stohl, A., Hittenberger, M., and Wotawa, G.: Validation of the lagrangian particle dispersion model FLEXPART against large-scale tracer experiment data, Atmos. Environ., 32, 4245–4264, http://dx.doi.org/10.1016/S1352-2310(98)00184-8doi:10.1016/S1352-2310(98)00184-8, 1998. Stohl, A., Eckhardt, S., Forster, C., James, P., Spichtinger, N., and Seibert, P.: A replacement for simple back trajectory calculations in the interpretation of atmospheric trace substance measurements, Atmos. Environ., 36, 4635–4648, http://dx.doi.org/10.1016/S1352-2310(02)00416-8doi:10.1016/S1352-2310(02)00416-8, 2002. Thompson, A., Doddridge, B., Witte, J., Hudson, R., Luke, W., Johnson, J. E., Johnson, B., Oltmans, S., and Weller, R.: A tropical Atlantic paradox: Shipboard and satellite views of a tropospheric ozone maximum and wave-one in January–February~1999, Geophys. Res. Lett., 27, 3317–3320, http://dx.doi.org/10.1029/1999GL011273doi:10.1029/1999GL011273, 2000. Thouret, V., Saunois, M., Minga, A., Mariscal, A., Sauvage, B., Solete, A., Agbangla, D., Nédélec, P., Mari, C., Reeves, C. E., and Schlager, H.: An overview of two years of ozone radio soundings over Cotonou as part of AMMA, Atmos. Chem. Phys., 9, 6157–6174, http://dx.doi.org/10.5194/acp-9-6157-2009doi:10.5194/acp-9-6157-2009, 2009. Tompkins, A., Diongue-Niang, A., Parker, D., and Thorncroft, C.: The African easterly jet in the ECMWF Integrated Forecast System: 4D-Var analysis, Q. J. Roy. Meteorol. Soc., 131, 2861–2885, http://dx.doi.org/10.1256/qj.04.136doi:10.1256/qj.04.136, 2005. Vizy, E K. and Cook, K H.: Development and application of a mesoscale climate model for the tropics: Influence of sea surface temperature anomalies on the West African monsoon, J. Geophys. Res., 107, 4023–4044, http://dx.doi.org/10.1029/2001JD000686doi:10.1029/2001JD000686, 2002. Williams, J E., Scheele, R., Van~Velthoven, P., Bouarar, I., Law, K., Josse, B., Peuch, V H., Yang, X., Pyle, J., Thouret, V., Barret, B., Liousse, C., Hourdin, F., Szopa, S., and Cozic, A.: Global Chemistry Simulations in the AMMA Multimodel Intercomparison Project, B. Am. Meteorol. Soc., 91, 611–624, http://dx.doi.org/10.1175/2009BAMS2818.1doi:10.1175/2009BAMS2818.1, 2010. Zampieri, M., Malguzzi, P., and Buzzi, A.: Sensitivity of quantitative precipitation forecasts to boundary layer parameterization: a flash flood case study in the Western Mediterranean, Nat. Hazards Earth Syst. Sci., 5, 603–612, http://dx.doi.org/10.5194/nhess-5-603-2005doi:10.5194/nhess-5-603-2005, 2005.