ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-10-5719-2010 Impact of West African Monsoon convective transport and lightning NO<sub>x</sub> production upon the upper tropospheric composition: a multi-model study Barret B. 1 2 Williams J. E. 3 Bouarar I. 4 Yang X. 5 Josse B. 6 Law K. 4 Pham M. 4 Le Flochmoën E. 1 2 Liousse C. 1 2 Peuch V. H. 6 Carver G. D. 5 Pyle J. A. 5 Sauvage B. 1 2 van Velthoven P. 3 Schlager H. 7 Mari C. 1 2 Cammas J.-P. 1 2 Laboratoire d'Aérologie/OMP, Université de Toulouse, Toulouse, France Laboratoire d'Aérologie, CNRS UMR 5560, Toulouse, France KNMI, De Bilt, The Netherlands LATMOS/IPSL, UPMC, Paris, France Centre for Atmospheric Science and Department of Chemistry, University of Cambridge, Cambridge, UK CNRM-GAME, Météo-France and CNRS URA 1357, Toulouse, France Institut für Physik der Atmosphäre, Deutsches Zentrum fur Luft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany 30 06 2010 10 12 5719 5738 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/10/5719/2010/acp-10-5719-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/10/5719/2010/acp-10-5719-2010.pdf

Within the African Monsoon Multidisciplinary Analysis (AMMA), we investigate the impact of nitrogen oxides produced by lightning (LiNO<sub>x</sub>) and convective transport during the West African Monsoon (WAM) upon the composition of the upper troposphere (UT) in the tropics. For this purpose, we have performed simulations with 4 state-of-the-art chemistry transport models involved within AMMA, namely MOCAGE, TM4, LMDz-INCA and p-TOMCAT. The model intercomparison is complemented with an evaluation of the simulations based on both spaceborne and airborne observations. The baseline simulations show important differences between the UT CO and O<sub>3</sub> distributions simulated by each of the 4 models when compared to measurements from the MOZAIC program and fom the Aura/MLS spaceborne sensor. We show that such model discrepancies can be explained by differences in the convective transport parameterizations and, more particularly, the altitude reached by convective updrafts (ranging between ~200–125 hPa). Concerning UT O<sub>3</sub>, the models exhibit a good agreement with the main observed features. Nevertheless the majority of models simulate low O<sub>3</sub> concentrations compared to both MOZAIC and Aura/MLS observations south of the equator, and rather high concentrations in the Northern Hemisphere. Sensitivity studies are performed to quantify the effect of deep convective transport and the influence of LiNO<sub>x</sub> production on the UT composition. These clearly indicate that the CO maxima and the elevated O<sub>3</sub> concentrations south of the equator are due to convective uplift of air masses impacted by Southern African biomass burning, in agreement with previous studies. Moreover, during the WAM, LiNO<sub>x</sub> from Africa are responsible for the highest UT O<sub>3</sub> enhancements (10–20 ppbv) over the tropical Atlantic between 10&deg; S–20&deg; N. Differences between models are primarily due to the performance of the parameterizations used to simulate lightning activity which are evaluated using spaceborne observations of flash frequency. Combined with comparisons of in-situ NO measurements we show that the models producing the highest amounts of LiNO<sub>x</sub> over Africa during the WAM (INCA and p-TOMCAT) capture observed NO profiles with the best accuracy, although they both overestimate lightning activity over the Sahel.

 References Barret, B., Ricaud, P., Mari, C., Attié, J.-L., Bousserez, N., Josse, B., Le Flochmoën, E., Livesey, N. J., Massart, S., Peuch, V.-H., Piacentini, A., Sauvage, B., Thouret, V., and Cammas, J.-P.: Transport pathways of CO in the African upper troposphere during the monsoon season: a study based upon the assimilation of spaceborne observations, Atmos. Chem. Phys., 8, 3231–3246, doi:10.5194/acp-8-3231-2008, 2008. Bechtold,~P., Bazile,~E., Guichard,~F., Mascart,~P., and Richard,~E.: A~mass flux convection scheme for regional and global models,~Q J. Roy. Meteor. Soc., 127, 869–886, 2001. Bernath,~P F., McElroy,~C T., Abrams,~M C., et al.: Atmospheric Chemistry Experiment (ACE): mission overview, Geophys. Res. Lett., 32, L15S01, \doidoi:10.1029/2005GL022386, 2005. Bian,~H., Chin,~M., Kawa,~S R., Duncan,~B., Arellano,~A., and Kasibharla,~P.: Sensitivity of global CO simulations to uncertainties in biomass burning sources,~J. Geophys. Res., 112, D23308, \doi10.1029/2006JD008376, 2007. Bond,~D W., Steiger,~S., Zhang,~R Y., et al.: The importance of NO<sub>x</sub> production by lightning in the tropics, Atmos. Environ., 36, 1509–1519, 2002. Bousserez,~N., Attie,~J.-L., Peuch,~V.-H., et al.: Evaluation of the MOCAGE chemistry transport model during the ICARTT/ITOP experiment,~J. Geophys. Res., 112, D10S42, doi:10.1029/2006JD007595, 2007. Carver,~G D., Brown,~P D., and Wild,~O.: The ASAD atmospheric chemistry integration package and chemical reaction databas, Comput. Phys., Comm., 105, 197–215, 1997. Chatfield,~R B., Guan,~H., Thompson,~A M., and Witte,~J C.: Convective lofting links Indian Ocean air pollution to paradoxical South Atlantic ozone maxima, Geophys. Res. Lett., 31, L06103, \doidoi:10.1029/2003GL018866, 2004. Christian,~H J., Blakeslee,~R J., Boccippio,~D J., et al.: Global frequency and distribution of lightning as observed from space by the optical transient detector,~J. Geophys. Res., 108, 4005, \doi10.1029/2002JD002347, 2003. Clerbaux, C., George, M., Turquety, S., Walker, K. A., Barret, B., Bernath, P., Boone, C., Borsdorff, T., Cammas, J. P., Catoire, V., Coffey, M., Coheur, P.-F., Deeter, M., De Mazière, M., Drummond, J., Duchatelet, P., Dupuy, E., de Zafra, R., Eddounia, F., Edwards, D. P., Emmons, L., Funke, B., Gille, J., Griffith, D. W. T., Hannigan, J., Hase, F., Höpfner, M., Jones, N., Kagawa, A., Kasai, Y., Kramer, I., Le Flochmoën, E., Livesey, N. J., López-Puertas, M., Luo, M., Mahieu, E., Murtagh, D., Nédélec, P., Pazmino, A., Pumphrey, H., Ricaud, P., Rinsland, C. P., Robert, C., Schneider, M., Senten, C., Stiller, G., Strandberg, A., Strong, K., Sussmann, R., Thouret, V., Urban, J., and Wiacek, A.: CO measurements from the ACE-FTS satellite instrument: data analysis and validation using ground-based, airborne and spaceborne observations, Atmos. Chem. Phys., 8, 2569–2594, doi:10.5194/acp-8-2569-2008, 2008. DeCaria,~A J., Pickering,~K E., Stenchikov,~G L., and Ott,~L E.: Lightning-generated NO<sub>x</sub> and its impact on tropospheric ozone production: a~3-D modeling study of a~STERAO – a~thunderstorm, J. Geophys. Res., 110, D14303, \doi10.1029/2004/JD005556, 2005. Dentener, F., van Weele, M., Krol, M., Houweling, S., and van Velthoven, P.: Trends and inter-annual variability of methane emissions derived from 1979–1993 global CTM simulations, Atmos. Chem. Phys., 3, 73–88, doi:10.5194/acp-3-73-2003, 2003. Dentener, F., Stevenson, D., Cofala, J., Mechler, R., Amann, M., Bergamaschi, P., Raes, F., and Derwent, R.: The impact of air pollutant and methane emission controls on tropospheric ozone and radiative forcing: CTM calculations for the period 1990–2030, Atmos. Chem. Phys., 5, 1731–1755, doi:10.5194/acp-5-1731-2005, 2005. Doherty, R. M., Stevenson, D. S., Collins, W. J., and Sanderson, M. G.: Influence of convective transport on tropospheric ozone and its precursors in a chemistry-climate model, Atmos. Chem. Phys., 5, 3205–3218, doi:10.5194/acp-5-3205-2005, 2005. Emanuel,~K A.: A~scheme for representing cumulus convection in large-scale models,~J. Atmos. Sci., 48, 2313–2335, 1991. Emanuel,~K A.: A~cumulus representation based on the episodic mixing model: the importance of mixing and microphysics in predicting humidity, AMS Meteorol. Monogr., 24(46), 185–192, 1993. Folkins,~I., Bernath,~P., Boone,~C., Donner,~L J., Eldering,~A., Lesins,~G., Martin,~R V., Sinnhuber,~B.-M., and Walker,~K.: Testing convective parameterizations with tropical measurements of \chemHNO_3, CO, \chemH_2O, and \chemO_3: implications for the water vapor budget,~J. Geophys. Res., 111, D23304, \doi10.1029/2006JD007325, 2006. Fu,~Q.: An accurate parameterization of the solar radiative properties of cirrus clouds for climate models,~J. Climate, 9, 2058–2082, 1996. Giannakopoulos,~C., Chipperfield,~T P., Law,~K S., et al.: Validation and intercomparison of wet and dry deposition schemes using Pb-210 in a~global three-dimensional off-line chemical transport model,~J. Geophys. Res., 104, 23761–23784, 1999. Hastenrath,~S.: Climate Dynamics of the Tropics, Kluwer Academic Publishers, Dordrecht, The Netherlands, 190–200, 1991. Hauglustaine,~D A., Hourdin,~F., Jourdain,~L., et al.: Interactive chemistry in the Laboratoire de Meteorologie Dynamique general circulation model: description and background tropospheric chemistry evaluation,~J. Geophys. Res., 109, D04314, \doi10.1029/2003JD003957, 2004. Heymsfield,~A J. and McFarquhar,~G M.: High albedos of cirrus in the tropical pacific warm pool: microphysical interpretations from CEPEX and from Kwajalein, Marshall Islands, J. Atmos. Sci., 53, 2424–2451, 1996. Hourdin,~F. and Armengaud,~A.: The use of finite-volume methods for atmospheric advection of trace species. Part I: Test of various formulations in a~general circulation model, Mon. Weather Rev., 127, 822–837, 1999. Hourdin,~F., Musat,~I., Bony,~S., et al.: The LMDZ4 general circulation model: climate performance and sensitivity to parametrized physics with emphasis on tropical convection, Clim. Dynam., 27, 787–813, 2006. Huntrieser,~H., Schlager,~H., Feigl,~C., and Höller,~H.: Transport and production of NO<sub>x</sub> in electrified thunderstorms: survey of previous studies and new observations at mid-latitudes,~J. Geophys. Res., 28247–28264, 1998. Janicot,~S., Thorncroft,~C D., Ali,~A., Asencio,~N., Berry,~G., Bock,~O., Bourles,~B., Caniaux,~G., Chauvin,~F., Deme,~A., Kergoat,~L., Lafore,~J.-P., Lavaysse,~C., Lebel,~T., Marticorena,~B., Mounier,~F., Nedelec,~P., Redelsperger,~J.-L., Ravegnani,~F., Reeves,~C E., Roca,~R., de Rosnay,~P., Schlager,~H., Sultan,~B., Tomasini,~M., Ulanovsky,~A., and ACMAD forecasters team: Large-scale overview of the summer monsoon over West Africa during the AMMA field experiment in 2006, Ann. Geophys., 26, 2569–2595, 2008. Jenkins, G. S. and Ryu, J.-H.: Space-borne observations link the tropical atlantic ozone maximum and paradox to lightning, Atmos. Chem. Phys., 4, 361–375, doi:10.5194/acp-4-361-2004, 2004. Josse,~B., Simon,~P., and Peuch,~V.-H.: Radon global simulations with the multiscale chemistry transport model MOCAGE, Tellus B, 56, 339–356, 2004. Jourdain,~L. and Hauglustaine,~D A.: The global distribution of lightning NO<sub>x</sub> simulated on-line in a~general circulation model, Phys. Chem. Earth, 26, 585–591, 2001 Labrador, L. J., von Kuhlmann, R., and Lawrence, M. G.: The effects of lightning-produced NO<sub>x</sub> and its vertical distribution on atmospheric chemistry: sensitivity simulations with MATCH-MPIC, Atmos. Chem. Phys., 5, 1815–1834, doi:10.5194/acp-5-1815-2005, 2005. Law,~K S., Plantevin,~P., Shallcross,~D., Rogers,~H., Pyle,~J., Grouhel,~C., Thouret,~V., and Marenco,~A.: Evaluation of modeled \chemO_3 using Measurement of Ozone by Airbus In-Service Aircraft (MOZAIC) data,~J. Geophys. Res., 103, 25721–25737, 1998. Law, K. S., Fierli, F., Cairo, F., Schlager, H., Borrmann, S., Streibel, M., Real, E., Kunkel, D., Schiller, C., Ravegnani, F., Ulanovsky, A., d'Amato, F., Viciani, S., and Volk, C. M.: Air mass origins influencing TTL chemical composition over West Africa during 2006 summer monsoon, Atmos. Chem. Phys. Discuss., 10, 15485–15536, doi:10.5194/acpd-10-15485-2010, 2010. Lawrence,~M G., von Kuhlmann,~R., Salzmann,~M., and Rasch,~P J.: The balance of effects of deep convective mixing on tropospheric ozone, Geophys. Res. Lett., 30, 1940, \doi10.1029/2003GL017644, 2003. Lawrence, M. G. and Salzmann, M.: On interpreting studies of tracer transport by deep cumulus convection and its effects on atmospheric chemistry, Atmos. Chem. Phys., 8, 6037–6050, doi:10.5194/acp-8-6037-2008, 2008. Lebel,~T., Parker,~D J., Flamant,~C., Bourles,~B., Marticorena,~B., Mougin, ~E., Peugeot,~C., Diedhiou, ~A., Haywood ~J M., Ngamini ~J B., et al.: The AMMA field campaigns: multiscale and multidisciplinary observations in the West African region, Q. J. Roy. Meteor. Soc., 136, 8–33, 2010. Lefevre,~F., Brasseur,~G P., Folkins,~I., Smith,~A K., and Simon,~P.: Chemistry of the 1991/1992 stratospheric winter: threedimensional model simulations,~J. Geophys. Res., 99, 8183–8195, 1994. 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.: Western african aerosols modelling with updated biomass burning emission inventories in the frame of the AMMA-IDAF program, Atmos. Chem. Phys. Discuss., 10, 7347–7382, doi:10.5194/acpd-10-7347-2010, 2010. Livesey,~N J., Filipiak,~M J., Froidevaux,~L., et al.: Validation of aura microwave limb sounder \chemO_3 and CO observations in the upper troposphere and lower stratosphere,~J. Geophys. Res., 113, D15S02, \doi10.1029/2007JD008805, 2008. Louis,~J.-F.: A~parametric model of vertical eddy-fluxes in the atmosphere, Bound-Lay. Meteorol., 17, 187–202, 1979. Mari,~C., Jacob,~D J., and Bechtold,~P.: Transport and scavenging of soluble gases in a~deep convective cloud, J. Geophys. Res., 105, 22255–22267, 2000. Mari,~C. and Prospero,~J.: African Monsoon Multidisciplinary Analysis-Atmospheric Chemistry (AMMA-AC): a~new IGAC task; IGACtivities Newsletter, 31, 2–13, 2005. Mari, C., Chaboureau, J. P., Pinty, J. P., Duron, J., Mascart, P., Cammas, J. P., Gheusi, F., Fehr, T., Schlager, H., Roiger, A., Lichtenstein, M., and Stock, P.: Regional lightning NO<sub>x</sub> sources during the TROCCINOX experiment, Atmos. Chem. Phys., 6, 5559–5572, doi:10.5194/acp-6-5559-2006, 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, doi:10.5194/acp-8-3951-2008, 2008. Martin,~R V., Jacob,~D J., Logan,~J A., et al.: Interpretation of TOMS observations of tropical tropospheric ozone with a~global model and in situ observations,~J. Geophys. Res., 107, 4351, \doi10.1029/2001JD001480, 2002. Marufu,~L., Dentener,~F., Lelieveld,~J., Andreae,~M O., and Helas,~G.: Photochemistry of the African troposphere: Influence of biomass-burning emissions,~J. Geophys. Res., 105, 14513–14530, 2000. Meijer,~E W., van Velthoven,~P F J., Brunner,~D W., et al.: Improvement and evaluation of the parameterisation of nitrogen oxide production by lightning, Phys. Chem. Earth, 26, 577–583, 2001. Michalon,~N., Nassif,~A., Saouri,~T., et al.: Contribution to the climatological study of lightning, Geophys. Res. Lett., 26, 3097–3100, 1999 Nedelec, P., Cammas, J.-P., Thouret, V., Athier, G., Cousin, J.-M., Legrand, C., Abonnel, C., Lecoeur, F., Cayez, G., and Marizy, C.: An improved infrared carbon monoxide analyser for routine measurements aboard commercial Airbus aircraft: technical validation and first scientific results of the MOZAIC III programme, Atmos. Chem. Phys., 3, 1551–1564, doi:10.5194/acp-3-1551-2003, 2003. Ordóñez, C., Elguindi, N., Stein, O., Huijnen, V., Flemming, J., Inness, A., Flentje, H., Katragkou, E., Moinat, P., Peuch, V.-H., Segers, A., Thouret, V., Athier, G., van Weele, M., Zerefos, C. S., Cammas, J.-P., and Schultz, M. G.: Global model simulations of air pollution during the 2003 European heat wave, Atmos. Chem. Phys., 10, 789–815, doi:10.5194/acp-10-789-2010, 2010. Pickering,~K E., Wang,~Y., Tao,~W K., Price,~C., and Muller,~J F.: Vertical distributions of lightning NO<sub>x</sub> for use in regional and global chemical transport models,~J. Geophys. Res., 103, 31203–31216, \doi10.1029/98JD02651, 1998. Pradier,~S., Attie,~J.-L., Chong,~M., et al.: Evaluation of 2001 springtime CO transport over West Africa using MOPITT CO measurements assimilated in a~global chemistry transport model, Tellus B, 58, 163–176, 2006. Prather,~M J.: Numerical advection by conservation of 2nd order moments,~J. Geophys. Res., 91, 6671–6681, 1986. Price,~C. and Rind,~D.: A~simple lightning parametrization for calculating global lightning distributions,~J. Geophys. Res., 97, 9919–9933, 1992. Price,~C. and Rind,~D.: What determines the cloud-to-ground lightning fraction in thunderstorms, Geophys. Res. Lett., 20, 463–466, 1993. Price,~C., Penner,~J., and Prather,~M.: NO<sub>x</sub> from lightning. 1. Global distribution based on lightning physics, J. Geophys. Res., 102, 5929–5941, 1997. Pumphrey,~H C., Filipiak,~M J., Livesey,~N J., et al.: Validation of middle-atmosphere carbon monoxide retrievals from MLS on Aura,~J. Geophys. Res., 112, D24S38, \doi10.1029/2007JD008723,2007. Rasch,~P J., Feichter,~J., and Law,~K.: A~comparison of scavenging and deposition processes in global models: results from the WCRP Cambridge Workshop of 1995, Tellus B, 52, 1025–1056, 2000. 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, doi:10.5194/acp-10-3027-2010, 2010. Redelsperger,~J L., Thorncroft,~C D., Diedhiou,~A., et al.: African monsoon multidisciplinary analysis – an international research project and field campaign, B. Am. Soc., 87, 1739–1746, 2006. Reeves, C. E., Formenti, P., Afif, C., Ancellet, G., Attie, J.-L., Bechara, J., Borbon, A., Cairo, F., Coe, H., Crumeyrolle, S., Fierli, F., Flamant, C., Gomes, L., Hamburger, T., Lambert, C., Law, K. S., Mari, C., Matsuki, A., 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. Discuss., 10, 7115–7183, doi:10.5194/acpd-10-7115-2010, 2010. Ridley,~B A., Pickering,~K E., and Dye,~J E.: Comments on the parameterization of lightning-produced NO in global chemistry-transport models, Atmos. Environ., 39, 6184–6187, 2005 Rossow,~W B., Walker,~A W., Beuschel,~D E., and Roiter,~M D.: International Satellite Cloud Climatology Project (ISCCP) Documentation of New Cloud Datasets. WMO/TD-No. 737, World Meteorological Organization, 115~pp., 1996. Sander,~S P., Friedl,~R R., Ravishankara,~A R., et al.: Chemical Kinetics and Photochemical Data for Use in Atmospheric studies, Evaluation No 15, JPL Publication 06–2, 2006. Saunois,~M., Mari,~C., Thouret,~V., et al.: An idealized two-dimensional approach to study the impact of the West African monsoon on the meridional gradient of tropospheric ozone,~J. Geophys. Res., 113, D07306, \doi10.1029/2007JD008707, 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, doi:10.5194/acp-9-6135-2009, 2009. Sauvage, B., Thouret, V., Cammas, J.-P., Gheusi, F., Athier, G., and Nédélec, P.: Tropospheric ozone over Equatorial Africa: regional aspects from the MOZAIC data, Atmos. Chem. Phys., 5, 311–335, doi:10.5194/acp-5-311-2005, 2005. Sauvage,~B., Thouret,~V., Cammas,~J.-P., Brioude,~J., Nedelec,~P., and Mari,~C.: Meridional ozone gradients in the African upper troposphere, Geophys. Res. Lett., 34, L03817, \doi10.1029/2006GL028542, 2007a. 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, doi:10.5194/acp-7-5357-2007, 2007b. Sauvage,~B., Martin,~R V., van Donkelaar,~A., and Ziemke,~J R.: Quantification of the factors controlling tropical tropospheric ozone and the South Atlantic maximum, J. Geophys. Res., 112, D11309, \doi10.1029/2006JD008008, 2007c. Schlager,~H., Konopka,~P., Schulte,~P., Schumann,~U., Ziereis,~H., Arnold,~F., Klemm,~M., Hagen,~D., Whitefield,~P., and Ovarlez,~J.: In situ observations of air traffic emission signatures in the North Atlantic flight corridor,~J. Geophys. Res., 102, 10739–10750, 1997. Schumann, U. and Huntrieser, H.: The global lightning-induced nitrogen oxides source, Atmos. Chem. Phys., 7, 3823–3907, doi:10.5194/acp-7-3823-2007, 2007. Shindell,~D T., Faluvegi,~G., Stevenson,~D S., et al.: Multimodel simulations of carbon monoxide: comparison with observations and projected near-future changes,~J. Geophys. Res., 111, D19306, \doi10.1029/2006JD007100, 2006. Stevenson,~D S., Dentener,~F J., Schultz,~M G., et al.: Multimodel ensemble simulations of present-day and near-future tropospheric ozone,~J. Geophys. Res., 111, D08301, \doi10.1029/2005JD006338, 2006. Stockwell,~W R., Kirchner,~F., Khun,~M., and Seefeld,~S.: A~new mechanism for regional atmospheric chemistry modelling,~J. Geophys. Res., 102, 25847–25879, 1997. Stockwell,~D Z., Giannakopoulos,~C., Plantevin,~P H., et al.: Modelling NO<sub>x</sub> from lightning and its impact on global chemical fields, Atmos. Environ., 33, 4477–4493, 1999. Teyssédre, H., Michou, M., Clark, H. L., Josse, B., Karcher, F., Olivié, D., Peuch, V.-H., Saint-Martin, D., Cariolle, D., Attié, J.-L., Nédélec, P., Ricaud, P., Thouret, V., van der A, R. J., Volz-Thomas, A., and Chéroux, F.: A new tropospheric and stratospheric Chemistry and Transport Model MOCAGE-Climat for multi-year studies: evaluation of the present-day climatology and sensitivity to surface processes, Atmos. Chem. Phys., 7, 5815–5860, doi:10.5194/acp-7-5815-2007, 2007. Thery,~C., Laroche,~P., and Blanchet,~P.: Lightning activity during EULINOX and estimations of NO<sub>x</sub> production by flashes, EULINOX – The European Lightning Nitrogen Oxides Experiment, No. 2000–28, DLR Forschungsbericht, DLR, Köln, 129–145, 2000. Thompson,~A., Doddridge,~B., Witte,~J., Hudson,~R., Luke,~W., Johnson,~J., 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, 2000. Thouret,~V., Marenco,~A., Logan,~J A., Nedelec,~P., and Grouhel,~C.: Comparisons of ozone measurements from the MOZAIC airborne program and the ozone sounding network at eight locations,~J. Geophys. Res., 103(D19), 25695–25720, 1998. Tiedtke,~M.: A~comprehensive mass flux scheme for cumulus parameterization in large-scale models, Mon. Weather. Rev., 117, 1779–1800, 1989. Tost, H., Jöckel, P., and Lelieveld, J.: Lightning and convection parameterisations – uncertainties in global modelling, Atmos. Chem. Phys., 7, 4553–4568, doi:10.5194/acp-7-4553-2007, 2007. Tost, H., Lawrence, M. G., Brühl, C., Jöckel, P., The GABRIEL Team, and The SCOUT-O3-DARWIN/ACTIVE Team: Uncertainties in atmospheric chemistry modelling due to convection parameterisations and subsequent scavenging, Atmos. Chem. Phys., 10, 1931–1951, doi:10.5194/acp-10-1931-2010, 2010. van der Werf, G. R., Randerson, J. T., Giglio, L., Collatz, G. J., Kasibhatla, P. S., and Arellano Jr., A. F.: Interannual variability in global biomass burning emissions from 1997 to 2004, Atmos. Chem. Phys., 6, 3423–3441, doi:10.5194/acp-6-3423-2006, 2006. Van Leer, B., Towards the ultimate conservative difference scheme. Part IV: A new approach to numerical convection, J. Comput. Phys., 23, 276–299, 1977. Wang,~K Y., Pyle,~J A., Sanderson,~M G., et al.: Implementation of a~convective atmospheric boundary layer scheme in a~tropospheric chemistry transport model,~J. Geophys. Res., 104, 23729–23745, 1999. Williams, J. E., Scheele, M. P., van Velthoven, P. F. J., Cammas, J.-P., Thouret, V., Galy-Lacaux, C., and Volz-Thomas, A.: The influence of biogenic emissions from Africa on tropical tropospheric ozone during 2006: a global modeling study, Atmos. Chem. Phys., 9, 5729–5749, doi:10.5194/acp-9-5729-2009, 2009a. Williams,~J E., Bouarar, I., Josse,~B., et al.: Global Chemistry simulations in the AMMA-Model Intercomparison project, B. Am. Meteorol. Soc., 91, 611–624, 2009b. Williams, J. E., Scheele, M. P., van Velthoven, P. F. J., Thouret, V., Saunois, M., Reeves, C. E., and Cammas, J.-P.: The influence of biomass burning on tropospheric composition over the tropical Atlantic Ocean and Equatorial Africa during the West African monsoon in 2006, Atmos. Chem. Phys. Discuss., 10, 7507–7552, doi:10.5194/acpd-10-7507-2010, 2010. Waters,~J W., et al.: The Earth Observing System Microwave Limb Sounder (EOS MLS) on the Aura satellite, IEEE T. Geosci. Remote, 44, 1075–1092, 2006. Yang,~X., Cox,~R A., Warwick,~N J., Pyle,~J A., Carver,~G D., O'Connor,~F M., and Savage,~N H.: Tropospheric bromine chemistry and its impacts on ozone: a~model study,~J. Geophys. Res., 110, D23311, \doi10.1029/2005JD006244, 2005. Yarwood,~G., Rao,~S., Yocke,~M., and Whitten,~G Z.: Updates to the Carbon Bond Mechanism: CB05, Yocke and company, Final Report, RT-04–00675, available online at: http://www.camx.com/publ/, 2005.