Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 9 5 2009 10.5194/acpd-9-21717-2009 http://www.atmos-chem-phys-discuss.net/9/21717/2009/ http://www.atmos-chem-phys-discuss.net/9/21717/2009/acpd-9-21717-2009.html http://www.atmos-chem-phys-discuss.net/9/21717/2009/acpd-9-21717-2009.pdf 21717 21783 2009-10-15 Reactive Halogens in the Marine Boundary Layer (RHaMBLe): the tropical North Atlantic experiments J. D. Lee G. McFiggans J. D. Allan A. R. Baker S. M. Ball A. K. Benton L. J. Carpenter R. Commane B. D. Finley M. Evans E. Fuentes K. Furneaux A. Goddard N. Good J. F. Hamilton D. E. Heard H. Herrmann A. Hollingsworth J. R. Hopkins T. Ingham M. Irwin C. E. Jones R. L. Jones W. C. Keene M. J. Lawler S. Lehmann A. C. Lewis M. S. Long A. Mahajan J. Methven S. J. Moller K. Müller T. Müller N. Niedermeier S. O'Doherty H. Oetjen J. M. C. Plane A. A. P. Pszenny K. A. Read A. Saiz-Lopez E. S. Saltzman R. Sander R. von Glasow L. Whalley A. Wiedensohler D. Young Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK National Centre for Atmospheric Sciences, University of York, Heslington, York, YO10 5DD, UK Centre for Atmospheric Sciences, School of Earth, Atmospheric & Environmental Sciences, University of Manchester, Manchester, M13 9PL, UK National Centre for Atmospheric Sciences, University of Manchester, Manchester, M13 9PL, UK School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK Department of Chemistry, University of Leicester, Leicester, LE1 7RH, UK Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK School of Physical Sciences, University of California, Irvine, CA 92697, USA Institute for Atmospheric Science, School of Earth and the Environment, University of Leeds, LS2 9JT, UK National Centre for Atmospheric Sciences, University of Leeds, Leeds, LS2 9JT, UK Leibniz Institute for Tropospheric Research, Permoserstraße 15, 04318, Leipzig, Germany Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, USA Department of Meteorology, University of Reading, P.O. Box 243, Earley Gate, Reading, RG6 6BB, UK School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA Mount Washington Observatory, North Conway, NH 03860, USA NASA Jet propulsion Laboratory, California Institute of Technology, Pasadena, 91109, USA Department of Atmospheric Chemistry, Max-Planck Institute of Chemistry, 55020 Mainz, Germany now at: Program in Science and Technology, Univ. of Washington, Bothell, WA 98011, USA sadly passed away, 28 July 2009 The NERC UK SOLAS-funded Reactive Halogens in the Marine Boundary Layer (RHaMBLe) programme comprised three field experiments. This manuscript presents an overview of the measurements made within the two simultaneous remote experiments conducted in the tropical North Atlantic in May and June 2007. Measurements were made from two mobile and one ground-based platforms. The heavily instrumented cruise D319 on the RRS Discovery from Lisbon, Portugal to São Vicente, Cape Verde and back to Falmouth, UK was used to characterise the spatial distribution of boundary layer components likely to play a role in reactive halogen chemistry. Measurements onboard the ARSF Dornier aircraft were used to allow the observations to be interpreted in the context of their vertical distribution and to confirm the interpretation of atmospheric structure in the vicinity of the Cape Verde islands. Long-term ground-based measurements at the Cape Verde Atmospheric Observatory (CVAO) on São Vicente were supplemented by long-term measurements of reactive halogen species and characterisation of additional trace gas and aerosol species during the intensive experimental period. <br><br> This paper presents a summary of the measurements made within the RHaMBLe remote experiments and discusses them in their meteorological and chemical context as determined from these three platforms and from additional meteorological analyses. Air always arrived at the CVAO from the North East with a range of air mass origins (European, Atlantic and North American continental). Trace gases were present at stable and fairly low concentrations with the exception of a slight increase in some anthropogenic components in air of North American origin, though NO_x mixing ratios during this period remained below 20 pptv. Consistency with these air mass classifications is observed in the time series of soluble gas and aerosol composition measurements, with additional identification of periods of slightly elevated dust concentrations consistent with the trajectories passing over the African continent. The CVAO is shown to be broadly representative of the wider North Atlantic marine boundary layer; measurements of NO, O₃ and black carbon from the ship are consistent with a clean Northern Hemisphere marine background. Aerosol composition measurements do not indicate elevated organic material associated with clean marine air. Closer to the African coast, black carbon and NO levels start to increase, indicating greater anthropogenic influence. Lower ozone in this region is possibly associated with the increased levels of measured halocarbons, associated with the nutrient rich waters of the Mauritanian upwelling. Bromide and chloride deficits in coarse mode aerosol at both the CVAO and on D319 and the continuous abundance of inorganic gaseous halogen species at CVAO indicate significant reactive cycling of halogens. <br><br> Aircraft measurements of O₃ and CO show that surface measurements are representative of the entire boundary layer in the vicinity both in diurnal variability and absolute levels. Above the inversion layer similar diurnal behaviour in O₃ and CO is observed at lower mixing ratios in the air that had originated from south of Cape Verde, possibly from within the ITCZ. ECMWF calculations on two days indicate very different boundary layer depths and aircraft flights over the ship replicate this, giving confidence in the calculated boundary layer depth. Alicke,~B., Hebestreit,~K., Stutz,~J., and Platt,~U.: Iodine oxide in the marine boundary layer, Nature, 397, 572–573, 1999. Allan,~B J., McFiggans,~G., Plane,~J M C., and Coe,~H.: Observations of iodine monoxide in the remote marine boundary layer, J. Geophys. Res., 105, 14361–14369, 2000. Allan,~B J., McFiggans,~G., Plane,~J M C., Coe,~H., and McFadyen,~G G.: The nitrate radical in the remote marine boundary layer, J. Geophys. Res., 105, 24191–24204, 2000. Allan,~B J., Plane~J M C., and McFiggans,~G.: Observations of OIO in the remote marine boundary layer, Geophys. Res. Lett., 28, 1945–1948, 2001. Allan,~J D., Topping,~D O., Good,~N., Irwin,~M., Flynn,~M., Williams,~P I., Coe,~H., Baker,~A., Martino,~M., Kaaden,~N., Wiedensohler,~A., Lehmann,~S., Müller,~K., Herrmann,~H., and McFiggans,~G.: Composition and properties of aerosol in the eastern Atlantic and influences on gas phase uptake rates, Atmos. Chem. Phys. Discuss., 9, 18331–18374, 2009. Ayers,~G P., Gillett,~R W., Cainey,~J M., and Dick,~A L.: Chloride and bromide loss from sea-salt particles in southern ocean air, J. Atmos. Chem., 33, 299–319, 1999. Ball,~S M., Hollingsworth,~A M., Humbles,~J.. LeBlanc,~C., Potin,~P., Langridge,~J M., LeCrane,~J.-P., and McFiggans,~G.: A spectroscopic study of molecular iodine emitted into the gas phase by seaweeds, Atmos. Chem. Phys. Discuss., submitted, 2009. Behnke,~W., Scheer,~V., and Zetzsch,~C.: Production of \chemBrNO_2, \chemBr and \chemClNO_2 from the reaction between sea spray aerosol and \chemN_2O_5, J. Aerosol Sci., 25, S277–S278, 1994. Birmili~W., Stratmann,~F., and Wiedensohler,~A.: J. Aerosol Sci., 30(4), 549–553, 1999. Bloss,~W J., Lee,~J D., Johnson,~G P., Sommariva,~R., Heard,~D E., Saiz-Lopez,~A., Plane,~J M C., McFiggans,~G., Coe,~H., Flynn,~M., Williams,~P I., Rickard,~A., and Fleming,~Z.: Impact of halogen monoxide chemistry upon boundary layer \chemOH and \chemHO_2 concentrations at a~coastal site, Geophys. Res. Lett., 32(6), L06814, doi:10.1029/2004GL022084, 2005. Bonsang,~B., Al Aabaour,~A., and Sciare,~J.: Diurnal variation of non-methane hydrocarbons in the subantarctic atmosphere, Environ. Chem., 5, 16–23, 2008. Carpenter,~L J.: Iodine in the marine boundary layer, Chem. Rev., 103, 4953–4962, 2003. Carpenter,~L J., Sturges,~W T., Penkett,~S A., Liss,~P S., Alicke,~B., Hebestreit,~K., and Platt,~U.: Short-lived alkyl iodides and bromides at Mace Head, Ireland: links to biogenic sources and halogen oxide production, J. Geophys. Res., 104(D1), 1679–1689, 1999. Carpenter,~L J., Malin,~G., Küpper,~F C., and Liss,~P S.: Novel biogenic iodine-containing trihalomethanes and other short-lived halocarbons in the coastal East Atlantic, Global Biogeochem. Cy., 14, 1191–1204, 2000. Carpenter,~L J., Jones,~C E., Dunk,~R M., Hornsby,~K E., and Woeltjen,~J.: Air-sea fluxes of biogenic bromine from the tropical and North Atlantic Ocean, Atmos. Chem. Phys., 9, 1805–1816, 2009. Chuck,~A L., Turner,~S M., and Liss,~P S.: Oceanic distributions and air-sea fluxes of biogenic halocarbons in the open ocean, J. Geophys. Res., 110, C10022, doi:10.1029/2004JC002741, 2005. Cubison,~M J., Coe,~H., and Gysel,~M.: A~modified hygroscopic tandem DMA and a~data retrieval method based on optimal estimation, Aerosol Sci. Technol., 36(7), 846–865, 2005. Currie, L A.: Limits for qualitative detection and quantitative determination, Anal. Chem., 40, 586, 1968. Edwards,~G D. and Monks,~P S.: Performance of a~single-monochromator diode array spectroradiometer for the determination of actinic flux and atmospheric photolysis frequencies, J. Geophys. Res. Atmos., 108(D16), 8546, doi:10.1029/2002JD002844, 2003. Fickert,~S., Adams,~J W., and Crowley,~J N.; Activation of \chemBr_2 and \chemBrCl via uptake of \chemHOBr onto aqueous salt solutions, J. Geophys. Res., 104, 23719–23727, 1999. Finley,~B D. and Saltzman,~E S.: Observations of \chemCl_2, \chemBr_2 and \chemI_2 in coastal marine air, J. Geophys. Res., 113, D21301, doi:10.1029/2008JD010269, 2008. Fuentes,~E., Coe,~H., Green,~D., and McFiggans,~G.: Laboratory-generated primary marine aerosol via bubble-bursting and atomization, Atmos. Meas. Tech. Discuss., 2, 2281–2320, 2009. Fuentes,~E., Coe,~H., Green,~D., and McFiggans,~G.: On the impacts of phytoplankton-derived organic matter on the properties of primary marine aerosol, Atmos. Chem. Phys. Discuss., submitted, 2009. Gabriel,~R., von Glasow,~R., Sander,~R., Andreae,~M., and Crutzen,~P J.: Bromide content of sea-salt aerosol particles collected over the Indian Ocean during INDOEX 1999, J. Geophys. Res., 107, 8032, doi:10.1029/2001JD001133, 2002. Garland,~J A. and Curtis,~H.: Emission of iodine from the sea surface in the presence of ozone, J. Geophys. Res., 86(C4), 3183–3186, 1981. Good,~N., Topping,~D O., Allan,~J D., Irwin,~M., Flynn,~M., Coe,~H., and McFiggans,~G.: Consistency between parameterisations of aerosol hygroscopicity and CCN activity during the RHaMBLE Discovery Cruise, Atmos. Chem. Phys. Discuss., in press, 2009. Gysel,~M., McFiggans,~G B., and Coe,~H.: Inversion of tandem differential mobility analyser (TDMA) measurements, J. Aerosol Sci., 40(2), 134–151, 2009. Haggerstone,~A.-L., Carpenter,~L J., Carslaw,~N., and McFiggans,~G.: Improved model predictions of \chemHO_2 with gas to particle mass transfer rates calculated using aerosol number size distributions, J. Geophys. Res., 110, D04303, doi:10.1029/2004JD005282, 2005. Hebestreit,~K., Stutz,~J., Rosen,~D., Matveiv,~V., Peleg,~M., Luria,~M., and Platt,~U.: DOAS measurements of tropospheric bromine oxide in mid-latitudes, Science, 283, 55–57, 1999. Herrmann,~H., Brüggemann,~E., Franck,~U., Gnauk,~T., Löschau,~G., Müller,~K., Plewka,~A., and Spindler,~G.: A~source study of PM in Saxony by size-segregated characterisation, J. Atmos. Chem., 55, 103–130, 2006. Hopkins,~J R., Lewis,~A C., and Read,~K A.: A~two-column method for long-term monitoring of Non-methane hydrocarbons (NMHC) and oxygenated volatile organic compounds (o-VOCs), J Environ. Monitor., 5, 8–13, 2002. Keene,~W C., Talbot,~R W., Andreae,~M O., Beecher,~K., Berresheim,~H., Castro,~M., Farmer,~J C., Galloway,~J N., Hoffmann,~M R., Li,~S.-M., Maben,~J R., Munger,~J W., Norton,~R B., Pszenny,~A A P., Puxbaum,~H., Westberg,~H., and Winiwarter,~W.: An intercomparison of measurement systems for vapor and particulate phase concentrations of formic and acetic acids, J. Geophys. Res., 94, 6457–6471, 1989. Keene,~W C., Maben,~J R., Pszenny,~A A P., and Galloway,~J N.: Measurement technique for inorganic chlorine gases in the marine boundary layer, Environ. Sci. Technol., 27, 866–874, 1993. Keene,~W C., Khalil,~M A K., Erickson,~D J., McCulloch,~A., Graedel,~T E., Lobert,~J M., Aucott,~M L., Gong,~S.-L., Harper,~D B., Kleiman,~G., Midgley,~P., Moore,~R M., Seuzaret,~C., Sturges,~W T., Benkovitz,~C M., Koropalov,~V., Barrie,~L A., and Li,~Y.-F.: Composite global emissions of reactive chlorine from natural and anthropogenic sources: Reactive chlorine emissions inventory, J. Geophys. Res., 104, 8429–8440, 1999. Keene,~W C., Stutz,~J., Pszenny,~A A P., Maben,~J R., Fischer,~E V., Smith,~A M., von Glasow,~R., Pechtl,~S., Sive,~B C., and Varner,~R K.: Inorganic chlorine and bromine in coastal New England air during summer, J. Geophys. Res., 112, D10S12, doi:10.1029/2006JD007689, 2007. Keene,~W C., Long,~M S., Pszenny,~A A P., Sander,~R., Maben,~J R., Wall,~A J., O'Halloran,~T L., Kerkewg,~A., Fischer, ~E V., and Schrems,~O.: Latitudinal variation in the multiphase chemical processing of inorganic halogens and related species over the eastern North and South Atlantic Oceans, Atmos. Chem. Phys., 9, 7361–7385, 2009. Kozlova,~E A. and Manning,~A C.: Methodology and calibration for continuous measurements of biogeochemical trace gas and \chemO_2 concentrations from a~300-m tall tower in central Siberia, Atmos. Meas. Tech., 2, 205–220, 2009. Langridge,~J M., Ball,~S M., Shillings,~A J L., and Jones,~R L.: A~broadband absorption spectrometer using light emitting diodes for ultrasensitive, in situ trace gas detection, Rev. Sci. Instrum., 79, 12, 2008. Lawler,~M J., Finley,~B D., Keene,~W C., Pszenny,~A A P., Read,~K A., von Glasow,~R., and Saltzman,~E S.: Pollution-enhanced reactive chlorine chemistry in the eastern tropical Atlantic boundary layer, Geophys. Res. Lett., 36, L08810, doi:10.1029/2008GL036666, 2009. Lawrence,~M G., Jockel,~P., and von Kuhlmann,~R.: What does the global mean OH concentration tell us?, Atmos. Chem. Phys., 1, 37–49, 2001. Lee,~J D., Moller,~S J., Read,~K A., Lewis,~A C., Mendes~L., and Carpenter,~L J.: Year round measurements of nitrogen oxides and ozone in the tropical North Atlantic marine boundary layer, J Geophys. Res., in press, 2009. Leser,~H., Hönninger,~G., and Platt,~U.: MAX-DOAS measurements of BrO and NO₂ in the marine boundary layer, Geophys. Res. Lett., 30(10), 1537, doi:10.1029/2002GL015811, 2003. Lewis,~A C., McQuaid,~J B., Carslaw,~N., and Pilling,~M J.: Diurnal cycles of short-lived tropospheric alkenes at a~north Atlantic coastal site, Atmos. Environ., 33, 2417–2422, 1999. Lowe,~D., Topping,~D O., and McFiggans,~G.: Modelling multi-phase halogen chemistry in the remote marine boundary layer: investigation of the inßuence of aerosol size resolution on predicted gas- and condensed-phase chemistry, Atmos. Chem. Phys. Discuss., 9, 5289–5320, 2009. Maben,~J R., Keene,~W C., Pszenny,~A A P., and Galloway,~J N.: Volatile inorganic chlorine in surface air over eastern North America, Geophys. Res. Lett., 22, 3513–3516, 1995. Mahajan,~A S., Oetjen,~H., Saiz-Lopez,~A., and Plane,~J M C.: A~modelling study of the vertical variation in halogen chemistry in the tropical remote marine boundary layer, Atmos. Chem. Phys., submitted, 2009. Martino,~M., Mills,~G P., Woeltjen,~J., and Liss,~P S.: A~new source of volatile organoiodine compounds in surface seawater, Geophys. Res. Lett., 36, L01609, doi:10.1029/2008GL036334, 2009. McFiggans,~G., Plane,~J M C., Allan,~B J., Carpenter,~L J., Coe,~H., and O'Dowd,~C.: A~modeling study of iodine chemistry in the marine boundary layer,~J. Geophys. Res A., 105, 14371–14385, 2000. McFiggans,~G., Cox,~R A., Mössinger,~J C., Allan,~B J., and Plane,~J M C.: Roles of iodine and nitrogen in the release of active chlorine from marine aerosols,~J. Geophys. Res., 107, 4271, doi:10.1029/2001JD000383, 2002. McFiggans, G., C. S. E. Bale, S. M. Ball, J. M. Beames, W. J. Bloss, L. J. Carpenter, J. Dorsey, R. Dunk, M. J. Flynn, K. L. Furneaux, M. W. Gallagher, D. E. Heard, A. Hollingsworth, K. Hornsby, T. Ingham, C. E. Jones, R. L. Jones, L. J. Kramer, J. Langridge, C. Leblanc, J-P. LeCrane, J. D. Lee, R. J. Leigh, I. Longley, A. S. Mahajan, P. S. Monks, H. Oetjen, A. J. Orr-Ewing, J. M. C. Plane, P. Potin, A. J. L. Shillings, F. Thomas, R. von Glasow, R. Wada, L. K. Whalley, and J. D. Whitehead, Iodine-mediated coastal particle formation: an overview of the Reactive Halogens in the Marine Boundary Layer (RHaMBLe) Roscoff coastal study, submitted to Atmos. Chem. Phys., 2009. Müller,~K., Lehmann,~S., van Pinxteren,~D., Gnauk,~T., Niedermeier,~N., Wiedensohler,~A., and Herrmann,~H.: Particle characterization at the Cape Verde Atmospheric Observatory during the 2007 RHaMBLe Intensive, Atmos. Chem. Phys. Discuss., accepted, 2009. Müller,~T., Schladitz,~A., Kaaden,~A., Ma,~N., and Wiedensohler,~A.: Spectral absorption coefficients and refractive index of Saharan mineral dust, Tellus, 61B(1), 79–95, 2009. Newberg,~J T., Matthew,~B M., and Anastasio,~C.: Chloride and bromide depletions in sea-salt particles over the northeastern Pacific Ocean, J Geophys. Res., 110, D06209, doi:10.1029/2004JD005446, 2005. O'Brien,~L M., Harris,~N R P., Robinson,~A D., Gostlow,~B., Warwick,~N., Yang,~X., and Pyle,~J A.: Bromocarbons in the tropical marine boundary layer at the Cape Verde Observatory, Meas. Model., 9, 4335–4379, 2009. Pechtl,~S., Lovejoy,~E R., Burkholder,~J B., and von Glasow,~R.: Modeling the possible role of iodine oxides in atmospheric new particle formations, Atmos. Chem. Phys., 6, 505–523, 2006. Peters,~C., Pechtl,~S., Stutz,~J., Hebestreit,~K., Honninger,~G., Heumann,~K G., Schwarz,~A., Winterlik,~J., and Platt,~U.: Reactive and organic halogen species in three different European coastal environments, Atmos. Chem. Phys., 5, 3357–3375, 2005. Plane,~J M C. and Saiz-Lopez,~A.: UV-Visible Differential Optical Absorption Spectroscopy (DOAS) in: Analytical techniques for atmospheric measurement, edited by: Heard,~D E., Wiley-Blackwell, Oxford, 2006. Pszenny,~A A P., Moldanova,~J., Keene,~W C., Sander,~R., Maben,~J R., Martinez,~M., Crutzen,~P J., Perner,~D., and Prinn,~R G.: Halogen cycling and aerosol pH in the Hawaiian marine boundary layer, Atmos. Chem. Phys., 4, 147–168, 2004. Quack,~B., Atlas,~E., Petrick,~G., Stroud,~V., Schauffler,~S., and Wallace,~D W R.: Oceanic bromoform sources for the tropical atmosphere, Geophys. Res. Lett., 31, L23S05, doi:10.1029/2004GL020597, 2004. Quack,~B., Atlas,~E., Petrick,~G., and Wallace,~D W R.: Bromoform and dibromomethane above the Mauritanian upwelling: Atmospheric distributions and oceanic emissions, J Geophys. Res., 112, D09312, doi:10.1029/2006jd007614, 2007. Rahn,~K A., Borys,~R D., and Duce,~R A.: Tropospheric halogen gases: Inorganic and organic components, Science, 192, 549–550, 1976. Ratte,~M., Bujok,~O., Spitzy,~A., and Rudolph,~J.: Photochemical alkene formation in seawater from dissolved organic carbon: Results from laboratory experiments,~J. Geophys. Res., 103, 5707–5717, 1998. Read,~K A., Mahajan,~A S., Carpenter,~L J., Evans,~M J., Faria,~B V E., Heard,~D E., Hopkins,~J R., Lee,~J D., Moller,~S J., Lewis,~A C., Mendes,~L., McQuaid,~J B., Oetjen,~H., Saiz-Lopez,~A., Pilling,~M J., and Plane,~J M C.: Extensive halogen-mediated ozone destruction over the tropical Atlantic Ocean, Nature, 453, 1232–1235, 2008. Read,~K A., Carpenter,~L J., Lee,~J D., Lewis,~A C., and Mendes,~L.; Intraannual cycles of NMVOCs in the tropical troposphere and their use for interpreting seasonal variability in CO, ~J. Geophys. Res., in press, 2009. Riemer,~D D., Milne,~P J., Zika,~R G., and Pos,~W H.: Photoproduction of nonmethane hydrocarbons (NMHCs) in seawater, Mar. Chem., 71, 177–198, 2000. Saiz-Lopez,~A. and Plane,~J M C.: Novel iodine chemistry in the marine boundary layer, Geophys. Res. Lett., 31, L04112, doi:10.1029/2003GL019215, 2004a. Saiz-Lopez,~A., Plane,~J M C., and Shillito,~J A., Bromine oxide in the mid-latitude marine boundary layer, Geophys. Res. Lett., 31, L03111, doi:10.1029/2003GL018956, 2004b. Saiz-Lopez,~A., Plane,~J M C., Mahajan,~A S., Anderson, ~P S., Bauguitte,~S J B., Jones,~A E., Roscoe,~H K., Salmon,~R A., Bloss,~W J., Lee,~J D., and Heard,~D E.: On the vertical distribution of boundary layer halogens over coastal Antarctica: implications for \chemO_3, HO_x, NO_x and the \chemHg lifetime, Atmos. Chem. Phys., 8, 887–900, 2008. Sander,~R., Keene,~W C., Pszenny,~A A P., Arimoto,~R., Ayers,~G P., Baboukas,~E., Cainey,~J M., Crutzen,~P J., Duce,~R A., Hönninger,~G., Huebert,~B J., Maenhaut,~W., Mihalopoulos,~N., Turekian,~V C., and van Dingenen,~R.: Inorganic bromine in the marine boundary layer: a~critical review, Atmos. Chem. Phys., 3, 1301–1336, 2003. Sander,~R. and Crutzen,~P J.: Model study indicating halogen activation and ozone destruction in polluted air masses transported to the sea, J Geophys. Res., 101, 9121–9138, 1996. Sander,~R., Rudich,~Y., von Glasow,~R., and Crutzen,~P J.: The role of \chemBrNO_3 in marine tropospheric chemistry: A~model study, Geophys. Res. Lett., 26, 2857–2860, 1999. Schmid,~H., Laskus,~L., Abraham,~H J., Baltensperger,~U., Lavanchy,~V., Bizjak,~M., Burba,~P., Cachier,~H., Crow,~D., Chow,~J., Gnauk,~T., Even,~A., ten Brink,~H M., Giesen,~K P., Hitzenberger,~R., Hueglin,~C., Maenhaut,~W., Pio,~C., Carvalho,~A., Putaud,~J.-P., Toom-Sauntry,~D., and Puxbaum,~H.: Results of the \qutcarbon conference international aerosol carbon round robin test stage I, Atmos. Environ., 35, 2111–2121, 2001. Simmonds,~P G., Derwent,~R G., Manning,~A J., Fraser,~P J., Krummel,~P B., O'Doherty,~S., Prinn,~R G., Cunnold,~D M., Miller,~B R., Wang,~H J., Ryall,~D B., Porter,~L W., Weiss,~R F., and Salameh,~P K.: AGAGE observations of methyl bromide and methyl chloride at Mace Head, Ireland, and Cape Grim, Tasmania, 1998–2001, J Atmos. Chem., 47, 243–269, 2004. Stutz,~J., Hebestreit,~K., Alicke,~B., and Platt,~U.: Chemistry of halogen oxides in the troposphere: Comparison of model calculations with recent field data, J Atmos. Chem., 34, 65–85, 1999. Toumi,~R.: BrO as a~Sink for Dimethylsulphide in the Marine Atmosphere, Geophys. Res. Lett., 21(2), 117–120, 1994. Toyota,~K., Takahashi,~M., and Akimoto,~H.: Modeling multi-phase halogen chemistry in the marine boundary layer with size-segregated aerosol module: Implications for quasi-size-dependent approach, Geophys. Res. Lett., 28, 2899–2902, 2001. Vogt,~R., Crutzen,~P., and Sander,~R.: A~mechanism for halogen release from sea-salt aerosol in the remote marine boundary layer, Nature, 383, 327–330, 1996. Vogt,~R., Sander,~R., von Glasow,~R., and Crutzen,~P J.: Iodine chemistry and its role in halogen activation and ozone loss in the marine boundary layer: A~model study, J Atmos. Chem., 32, 375–395, 1999. von Glasow,~R., Sander,~R., Bott,~A., and Crutzen,~P J.: Modeling halogen chemistry in the marine boundary layer. 1. Cloud-free MBL, J Geophys. Res., 107, 4341, doi:10.1029/2001JD000942, 2002a. von Glasow,~R., Sander,~R., Bott,~A., and Crutzen,~P J.: Modeling halogen chemistry in the marine boundary layer. 2. Interactions with sulfur and cloud-covered MBL,~J. Geophys. Res., 107, 4323, doi:10.1029/2001JD000943, 2002b. von Glasow,~R., von Kuhlmann,~R., Lawrence,~M G., Platt,~U., and Crutzen,~P J.: Impact of reactive bromine chemistry in the troposphere. Atmos. Chem. Phys., 4, 2481–2497, 2004. von Glasow,~R., and Crutzen,~P J.: Tropospheric halogen chemistry, in: Treatise on Geochemistry Update 1, vol.4.02, edited by: Holland,~H D. and Turekian,~K K., Elsevier-Pergamon, Oxford, 1–67, 2007. Whalley,~L K., Furneaux,~K L., Gravestock,~T., Atkinson,~H., Bale,~C S. E, Ingham,~T., Bloss,~W., and Heard,~D E.: Detection of iodine monoxide radicals in the marine boundary layer using laser induced fluorescence spectroscopy, J Atmos. Chem., 58, 19–39, 2007. Whalley,~L K., Furneaux,~K L., Goddard,~A., Lee,~J D., Mahajan,~A., Oetjen,~H., Read,~K A., Kaaden,~N., Carpenter,~L J., Lewis,~A C., Plane,~J M C., Saltzman,~E S., Wiedensohler,~A., and Heard,~D E.: The Chemistry of OH and \chemHO_2 radicals in the boundary layer over the tropical Atlantic Ocean, Atmos. Chem. Phys. Discuss., 9, 15959–16009, 2009 2009. Williams,~J., Fischer,~H., Wong,~S., Crutzen,~P J., Scheele,~M P., and Lelieveld,~J.: Near equatorial CO and \chemO_3 profiles over the Indian Ocean during the winter monsoon: High \chemO_3 levels in the middle troposphere and interhemispheric exchange,~J. Geophys. Res. Atmos., 107, 8007, doi:10.1029/2001JD001126, 2002. Williams,~P I., McFiggans,~G., and Gallagher,~M W.: Latitudinal aerosol size distribution variation in the Eastern Atlantic Ocean measured aboard the FS-Polarstern, Atmos. Chem. Phys., 7, 2563–2573, 2007. Zhou~Z. and Mopper,~K.: Carbonyl compounds in the lower marine troposphere over the Caribbean Sea and Bahamas,~J. Geophys. Res., 98, 2385–2392, 1993.