ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-9-3681-2009 Peroxy radical observations over West Africa during AMMA 2006: photochemical activity in the outflow of convective systems Andrés-Hernández M. D. 1 Kartal D. 1 Reichert L. 1 Burrows J. P. 1 Meyer Arnek J. 2 Lichtenstern M. 3 Stock P. 3 Schlager H. 3 Institute of Environmental Physics, University of Bremen, Germany German Remote Sensing Data Center (DFD), Oberpfaffenhofen, Germany Institute of Atmospheric Physics, German Aerospace Center (DLR), Oberpfaffenhofen, Germany 05 06 2009 9 11 3681 3695 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/9/3681/2009/acp-9-3681-2009.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/9/3681/2009/acp-9-3681-2009.pdf

Peroxy radical measurements made on board the DLR-Falcon research aircraft over West Africa within the African Monsoon Multidisciplinary Analysis (AMMA) campaign during the 2006 wet monsoon are presented in this study. The analysis of data focuses on the photochemical activity of air masses sampled during episodes of intense convection and biomass burning. Generally, the total sum of peroxy radical mixing ratios, measured in the outflow of convective clouds, are quite variable but occasionally are coupled with the NO variations indicating the coexistence or simultaneous emission of NO<sub>x</sub>, with a potential radical precursor (i.e. formaldehyde, acetone or peroxides), which has likely been transported to higher atmospheric altitudes. Based on the measurements, significant O<sub>3</sub> production rates around 1 ppb/h in the MCS outflow are estimated by using a box model with simplified chemistry. Peroxy radicals having mixing ratios around 20–25 pptv and with peak values of up to 60–70 pptv are measured within biomass burning plumes, detected at the coast in Ghana. Calculations of back-trajectory densities confirm the origin of these air masses being a biomass burning region at southern latitudes and close to the Gulf of Guinea, according to satellite pictures. <br></br> Measured peroxy radical concentrations agree reasonably with modelled estimations taking into account simple local chemistry. Moreover, the vertical profiles taken at the aircraft base in Ouagadougou, Burkina Faso, indicate the common feature of having maximum concentrations between 2 and 4 km, in agreement with other literature values obtained under similar conditions.

 References Agustí-Panareda, A. and Beljaars, A.: ECMWF's contribution to AMMA, ECMWF Newsletter, No 115, 19–27, Spring~2008. 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, 2009. Andrés Hernández, M. D., Burkert, J., Reichert, L., Stöbener, D., Meyer-Arnek J., Burrows, J. P., Dickerson, R. R., and Doddridge, B.: Marine boundary layer peroxy radical chemistry during the AEROSOLS99 campaign: measurements and analysis, J. Geophys. Res, 106(D18), 20833–20846, 2001. Bechara, J., Borbon, A., Lambert, C., and Perros, P.: Evidence of deep convective transport of VOC trace gases in the upper tropical troposphere during the AMMA experiment, to be submitted, ACP, AMMA special issue, 2009. Bhetanabhotla, M. N., Crowell, B. A., Cowouvinos, A., et al.: Simulation of trace species production by lightning and corona discharge in moist air, Atmos. Environ., 19, 1391–1397, 1985. Burkert, J., Behmann, T., Andrés Hernández, M.D., Weißenmayer, M., Perner, D., and Burrows, J.P.: Measurements of peroxy radicals in a forested area in Portugal, Chemosphere Global Change Sci., 3(3), 327–338, 2001a. Burkert, J., Andrés-Hernández, M. D., Stöbener, D., Burrows, J. P., Weissenmayer, M., and Kraus, A.: Peroxy radical and related trace gas measurements in the boundary layer above the Atlantic Ocean, J. Geophys. Res., 106(6), 5457~pp., 2001b. Burkert, J., Andrés-Hernández, M. D, Reichert, L., Meyer-Arnek, J., Doddridge, B,. Dickerson, R. R., Muehle, J., Zahn, A., Carsey, T., and Burrows, J. P.: Trace gas and radical diurnal behavior in the marine boundary layer during INDOEX~1999, J. Geophys. Res., 108 (D8), 8000, doi:10.1029/2002JD002790, 2003. Buxton, G. V., and Salmon G. A.: On the chemistry of inorganic free radicals in cloud water, Prog. React. Kinet. Mec., 28, 257–297, 2003. Cantrell, C. A., Shetter, R. E., Gilpin, T. M., Calvert, J. G., Eisele, F. L., and Tanner, D. J.: Peroxy radical concentrations measured and calculated from trace gas measurements in the Mauna Loa Photochemistry Experiment~2, J. Geophys. Res., 101, 14653–14664, 1996a. Cantrell, C. A., Shetter R. E., and Calvert, J. G.: Dual-Inlet chemical amplifier for atmospheric peroxy radical measurements, Anal. Chem., 68, 4194–4199, 1996b. Cantrell, C. A., Edwards, G. D., Stephens, S., Mauldin, L., et al.: Peroxy radical behaviour during the Transport and Chemical Evolution over the Pacific (TRACE-P) campaign as measured aboard the NASA P-3B aircraft, J. Geophys. Res., 108(D20), 8797, doi:10.1029/2003JD003674, 2003a. Cantrell, C. A., Edwards, G. D., Stephens, S., Mauldin, L., Kosciuch , E., Zondlo, M., and Eisele, F.: Peroxy radical observations using chemical ionization mass spectrometry during TOPSE, J. Geophys. Res., 108(D6), 8371, doi: 10.1029/2002JD002715, 2003b. Cantrell, C. A., Mauldin, L., Zondlo, M., Eisele, F. et al.: Steady state free radical budgets and ozone photochemistry during TOPSE, J. Geophys. Res., 108(D4), 8361, doi:10.1029/2002JD002198, 2003c. Carslaw, N., Creasey, D. J., Heard, D. E., Lewis, A. C., McQuaid, J. B., Pilling, M. J., Monks, P. S., Bandy B. J., and Penkett S. A: Modelling OH, HO<sub>2</sub>, and RO<sub>2</sub> in the marine boundary layer: 1 Model construction and comparison with field measurements, J. Geophys. Res., 104(D23), 30241–30255, 1999. Cohan, D. S., Schultz, M. G., and Jacob, D. J.: Convective injection and photochemical decay of peroxides in the tropical upper troposphere: methyl iodide as a tracer of marine convection, J. Geophys. Res., 104(D5), 5717–5724, 1999. Cooper, O. R., Stohl, A., Trainer, M., et al.: Large upper tropospheric ozone enhancements above midlatitude North America during summer: In situ evidence from the IONS and MOZAIC ozone measurement network, J. Geophys. Res., 111, D24S05, doi:10.1029/2006JD007306, 2006. Coppens, F., Berton, R., Bondiou-Clergerie, A., and Gallimberti, I.: Theoretical estimate of NO<sub>x</sub> production in lightning corona, J. Geophys. Res., 103, 10769–10785, 1998. Eneroth, K., Kjellstrom E., and Holmen, K.: A trajectory climatology for Svalbard; investigating how atmospheric flow patterns influence observed tracer concentrations, Phys. Chem. Earth., 28, 1191–1203, 2003. Faloona, I., Tan, D., Brune, W. H., Jaeglé, L. D., Jacob, J., et al.: Observations of HO<sub>x</sub> and its relationship with NO<sub>x</sub> in the upper troposphere during SONEX, J. of Geophys. Res., 105(D3), 3771–3783, 2000. Fleming, Z. L., Monks, P. S., Rickard, A. R., Heard, D. E., Bloss, W. J., Seakins, P. W., Still, T. J., Sommariva, R., Pilling, M. J., Morgan, R., Green, T. J., Brough, N., Mills, G. P., Penkett, S. A., Lewis, A. C., Lee, J. D., Saiz-Lopez, A., and Plane, J. M. C.: Peroxy radical chemistry and the control of ozone photochemistry at Mace Head, Ireland during the summer of 2002, Atmos. Chem. Phys., 6, 2193–2214, 2006. Fleming, Z. L., Monks, P. S., Rickard, A. R., Bandy, B. J., Brough, N., Green, T. J., Reeves, C. E., and Penkett, S. A.: Seasonal dependence of peroxy radical concentrations at a Northern hemisphere marine boundary layer site during summer and winter: evidence for radical activity in winter, Atmos. Chem. Phys., 6, 5415–5433, 2006. Folkins, I., Wennberg, P. O., Hanisco, T. F., Anderson, J. G., and Salawitch, R. J.: OH, HO<sub>2</sub>, and NO in two biomass burning plumes: Sources of HO<sub>x</sub> and implications for ozone production, Geophys. Res. Lett., 24, 3185–3188, 1997. Gerbig, C., Kley, D., Volz-Thomas, A. , et al.: Fast response resonance fluorescence CO measurements aboard the C-130: Instrument characterisation and measurements made during North Atlantic Regional Experiment 1993, J. Geophys. Res., 101, 29229–29238, 1996. Glindemann, D. M., Edwards, M., and Schrems, O.: A Phosphine and methylphosphine production by simulated lightning – a study for the volatile phosphorus cycle and cloud formation in the earth atmosphere, Atmos. Environ., 38, 6867–6874, 2004. Green, T. J., Brough, N., Reeves, C. E., Edwards, G. D., Monks P. S., and Penkett, S. A.: Airborne measurements of peroxy radicals using the PERCA technique, J. Environ. Monitoring., 5, 75–83, 2003. Jaeglé, L., Jacob, D. J., Wennberg, P. O., et al.: Observed OH and HO<sub>2</sub> in the upper troposphere suggest a major source from convective injection of peroxides, Geophys. Res. Lett., 24, 3181–3184, 1997a. Jaeglé, L., Jacob, D. J., Wang, Y., Weinheimer, A. J., Ridley, B. A., Campos, T. L., Sachse, G. W., and Hagen, D. E.: Sources and chemistry of NO<sub>x</sub> in the upper troposphere over the United States, Geophys. Res. Lett., 25(10), 1705–1708, doi:10.1029/97GL03591, 1997b. Jaeglé, L., Jacob, D. J., Brune W. H., et al.: Ozone production in the upper troposphere and the influence of aircraft during SONEX: Approach of NO<sub>x</sub>-saturated conditions, Geophys. Res. Lett., 26(20), 3081–3084, 1999. Jaeglé, L., Jacob, D. J., Brune W. H., and Wennberg, P. O.: Chemistry of HO<sub>x</sub> radicals in the upper troposphere, Atmospheric Environment, 35, 469–489, 2001. Kartal, D., Andrés-Hernández, M. D., Reichert, L., Schlager, H., and Burrows, J. P.: Characterisation of a DUALER instrument for the airborne measurement of peroxy radicals during AMMA 2006, to be submitted to ACP, 2009. Lelieveld, J. and Crutzen, P. J.: Role of deep cloud convection in the ozone budget of the troposphere, Science, 264(5166), 1759–1761, 1994. Lelieveld, J., Butler, T. M., Crowley, J. N., et al.: Atmospheric oxidation capacity sustained by a tropical forest, Letters to Nature, 452, 737–740, doi:10.1038/nature06870, 2008. 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, 2008. Mauersberger, G.: The influence of cloud chemistry on the budget of photo-oxidants, Transactions on Ecology and the Environment, 6, WIT Press, ISSN 1743-3541, 1995. McKeen, S. A., Gierczak, T., Burkholder J. B., et al.: The photochemistry of acetone in the upper troposphere: a source of odd-hydrogen radicals, Geophys. Res. Lett., 24, 3177–3180, 1997. Meyer-Arnek, J., Ladstätter-Weißenmayer, A., Richter, A., Wittrock, F., and Burrows, J. P.: A study of the trace gas columns of O<sub>3</sub>, NO<sub>2</sub> and HCHO over Africa in September~1997, Faraday Discuss., 130, 387–405, doi:10.1039/b502106p, 2005. Miyazaki, Y., Kita, K. , Kondo, Y., et al.: Springtime photochemical ozone production observed in the upper troposphere over east Asia, J. Geophys. Res., 107, 8398, doi:10.1029/ 2001JD000811, 2002. Monks P. S., Carpenter, L. J., and Penkett, S. A.: Night-time peroxy radical chemistry in the remote marine boundary layer over the Southern ocean, Geophys. Res. Lett., 23(5), 535–538, 1996. Pinart, J., Smirdec, M., Pinart, M. E., et al.: Quantitative study of the formation of inorganic chemical species following corona discharge: I. Production of HNO<sub>2</sub> and HNO<sub>3</sub> in a composition controlled humid atmosphere, Atmos. Environ., 30, 129–132, 1996. Prather, M. J., and Jacob, D. J. : A persistent imbalance in HO<sub>x</sub> and NO<sub>x</sub> photochemistry of the upper troposphere driven by deep tropical convection, Geophys. Res. Lett., 24, 3189–3192, 1997. Reeves, C. E., Ancellet, G., Attie, J.-L., et al.: Chemical characterisation of the West Africa Monsoon during AMMA, ACP, to be submitted, 2009. Rozanov, V. V., Buchwitz, M., Eichmann, K.-U., de Beek R., and Burrows, J. P.: Sciatran – a new radiative transfer model for geophysical applications in the 240–2400 NM spectral region: the pseudo-spherical version, Adv. Space. Res., 29(11), 1831–1835, 2002. Sander, S. P., Orkin, V. L., Kurylo, M. J., Golden, D. M., Huie, R. E., Kolb, C. E. , Finlayson-Pitts, B. J., Molina, M. J., Friedl, R. R., Ravishankara, A. R., Moortgat, G. K., Keller-Rudek, H., Wine, P. H. : Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies Evaluation Number~15, JPL publication 06–2, Jet Propulsion Laboratory, 2006. Saunders, S. M., Jenkin, M. E., Derwent, R. G., and Pilling, M. J.: Protocol for the development of the Master Chemical Mechanism, MCM v3 (Part A): tropospheric degradation of non-aromatic volatile organic compounds, Atmos. Chem. Phys., 3, 161–180, 2003. Schlager, H., Konopka, P. Schulte, P., Schumann, U., Ziereis, H., Arnold, F., Klemm, M., Hagen, D., Whitefield, P., Ovarlez, J.: In situ observations of air traffic emission signatures in the North Atlantic flight corridor, J. Geophys. Res., 102, 10739–10750, 1997. Schlager, H., Lichtenstern, M., Stock, P., et al., : Aircraft measurements of the chemical composition in fresh and aged outflow from Mesoscale Convective Systems in West Africa, ACP, to be submitted, AMMA Special Section, 2009. Schulte, P., Schlager, H., Schumann, U., Baughcum, St. L., Deidwig F.: NO<sub>x</sub> emission indices of subsonic long-range jet aircraft at cruise altitude: In situ measurements and predictions, J. Geophys. Res., 102, 21431–21442, 1997. Seigneur, C. and Saxena, P.: The impact of cloud chemistry on photochemical oxidant formation, Water Air Soil Poll., 24, 419–429, 1985. Shi, Q., Belair, S. D., Francisco, J. S., and Kais, S.: On the interactions between atmospheric radicals and cloud droplets: A molecular picture of the interface, PNAS, 100(17), 9686–9690, 2003. Stohl, A., Wotawa, G., Seibert, P., and Kromp-Kolb, H.: Interpolation errors in wind fields as a function of spatial and temporal resolution and their impact on different types of kinematic trajectories. J. Appl. Meteor., 34, 2149–2165, 1995. Stohl, A. and Seibert, P.: Accuracy of trajectories as determined from the conservation of meteorological tracers. Q. J. Roy. Met. Soc., 124, 1465–1484, 1998. Volz-Thomas A., Pätz, H.-W., Houben, N., Konrad, S., Mihelcic, D.,Klüpfel, T., and Perner, D.: Inorganic trace gases and peroxy radicals during BERLIOZ at Pabstthum: An investigation of the photostationary state of NO<sub>x</sub> and O3, J. Geophys. Res., 108(D4), 8248, doi:10.1029/2001JD001255, 2003. Wennberg, P. O., Hanisco, T. F., Jaeglé, L., Jacob, D. J., et al.: Hydrogen radicals, nitrogen radicals, and the production of O<sub>3</sub> in the upper troposphere, Science, 279, 49–53, 1998. Wittrock, F., Richter, A., Oetjen, H., Burrows, J. P., Kanakidou, M., Myriokefalitakis, S., Volkamer, R., Beirle, S., Platt U., and Wagner, T.: Simultaneous global observations of glyoxal and formaldehyde from space, Geophys. Res. Lett., 33, L16804, doi: 10.1029/2006GL026310, 2006. Zanis, P., Monks, P. S., Green, T. J., Schuepbach, E., Carpenter, L. J., Mills, G. P., Rickard, A. R. and Penkett, S. A.: Seasonal variation of peroxy radicals in the lower free troposphere based on observations from the FREE Tropospheric Experiments in the Swiss Alps, Geophys. Res. Lett., 30(10), 1497, doi:10.1029/2003GL017122, 2003. Zuo, Y. and Deng, Y: Evidence for the production of hydrogen peroxide in rainwater by lightning during thunderstorms, Geochim. Cosmochim. Ac., 63(19/20), 3451–3455, 1999. Ziereis, H., Schlager, H., Schulte, P., van Velthoven, P., and Slemr, F.: Distributions of NO, NO<sub>x</sub>, and NO<sub>y</sub> in the upper troposphere and lower stratosphere between 28 and 61&deg; N during POLINAT~2, J. Geophys. Res., 105, 3653–3664, 2000.