Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 7 2 2007 10.5194/acpd-7-4521-2007 http://www.atmos-chem-phys-discuss.net/7/4521/2007/ http://www.atmos-chem-phys-discuss.net/7/4521/2007/acpd-7-4521-2007.html http://www.atmos-chem-phys-discuss.net/7/4521/2007/acpd-7-4521-2007.pdf 4521 4595 2007-04-02 The potential importance of frost flowers, recycling on snow, and open leads for Ozone Depletion Events M. Piot matthias.piot@iup.uni-heidelberg.de R. von Glasow Institute of Environmental Physics, University of Heidelberg, Germany now at: School of Environmental Sciences, University of East Anglia, Norwich, UK We present model studies with the one-dimensional model MISTRA to investigate the potential role of frost flowers, recycling on snow, and open leads in the depletion of tropospheric ozone in the Arctic spring. In our model, we assumed frost flower aerosols to be the major source of bromine. We show that a major ozone depletion event can be satisfactorily reproduced only if the recycling on snow of deposited bromine into gas phase bromine is assumed. In the model, this cycling is more efficient than the bromine explosion process and maintains sufficiently high levels of bromine to deplete ozone down to few nmol mol^−1 within four days. We assessed the influence of different surface combinations (open lead/frost flowers) on the chemistry in the model. Results showed noticeable modifications affecting the composition of aerosols and the deposition velocities. A model run with a series of coupled frost flower fields and open leads, separated by large areas of snow, showed results comparable with field observations. In addition, we studied the effects of modified temperature of either the frost flower field or the ambient airmass. A warmer frost flower field increases the relative humidity and the aerosol deposition rate. The deposition/re-emission process gains in importance, inducing more reactive bromine in the gas phase, and a stronger ozone depletion. A decrease of 1 K in airmass temperature shows in our model that the aerosol uptake capacities of all gas phase species substantially increases, leading to enhanced uptake of acids from the gas phase. Consequently, the so-called bromine explosion accelerated and O₃ mixing ratios decreased. In our model representation, variations in wind speed affected the aerosol source function and influenced the amount of bromine in the atmosphere and thus the ozone depletion strength. Recent studies have suggested the important role of the precipitation of calcium carbonate (CaCO₃) out of the brine layer for the possible acidification of the liquid phase by acid uptake. Our investigation showed that this precipitation is a crucial process for the timing of the bromine explosion in aerosols. Nevertheless, model runs with either 50% precipitation or complete precipitation displayed a relatively weak difference in ozone mixing ratios after four simulated days. By considering conditions typical for "Arctic Haze" pollution events at the start of the run we obtained a low pH in frost flower aerosols due to a greater mixing ratio of SO₂, and a strong recycling efficiency via large aerosol number concentration. The aerosol acidification during a haze event most likely intensifies the ozone depletion strength and occurrence. The comparison between our modeled deposition on snow and sampled snow at Barrow (Alaska) shows that approximately 75% of deposited bromine may be re-emitted into the gas phase as Br₂/BrCl. Among several non-halogen fluxes from the snow, model simulations showed that only HONO affects the chemistry. Finally, we investigated the release of Br₂ potentially produced by heterogeneous reactions directly on frost flowers. In this case, we obtained unrealistic results of aerosol compositions and deposition rates on snow compared to observations in the Arctic. Anderson, L G. and Jones, E P.: Measurements of total alkalinity, calcium and sulphate in natural sea ice, J. Geophys. Res., 90, 9194–9198, 1985. Anlauf, K G., Mickle, R E., and Trivett, N. B A.: Measurement of ozone during Polar Sunrise Experiment 1992, J. Geophys. Res., 99, 25 345–25 353, 1994. Argentini, S., Viola, A P., Mastrantonio, G., Maurizi, A., Georgiadis, T., and Nardino, M.: Characteristics of the boundary layer at Ny-Alesund in the Arctic during the ARTIST field experiment, Annals Geoph., 46, 185–195, 2003. Barrie, L A. and Hoff, R M.: The oxidation rate and residence time of sulphur dioxide in the arctic atmosphere, Atmos. Environ., 18, 2711–2722, 1984. Barrie, L A., Bottenheim, J W., Schnell, R C., Crutzen, P J., and Rasmussen, R A.: Ozone destruction and photochemical reactions at polar sunrise in the lower Arctic atmosphere, Nature, 334, 138–141, 1988. Barrie, L A., den Hartog, G., Bottenheim, J W., and Landsberger, S.: Anthropogenic aerosols and gases in the lower troposphere at Alert, Canada in April 1986, J. Atmos. Chem., 9, 101–127, 1989. Barrie, L A., Bottenheim, J W., and Hart, W R.: Polar Sunrise Experiment 1992 (PSE 1992): Preface, J. Geophys. Res., 99, 25 313–25 314, 1994. Beine, J., Jaffe, D A., Stordal, F., Engardt, M., Solberg, S., Schmidbauer, N., and Holmen, K.: NO_x during ozone depletion events in the arctic troposphere at Ny-Alesund, Svalbard, Tellus, 49B, 556–565, 1997. Bischoff, J L., Fitzpatrick, J A., and Rosenbauer, R J.: The solubility and stabilization of ikaite (\chemCaCO_3. 6\chemH_2O) from 0° to 25°C: Environmental and paleoclimatic implications for thinolite tufa, J. Geol., 101, 21–33, 1993. Bottenheim, J W., Gallant, A J., and Brice, K A.: Measurements of NO_y species and \chemO_3 at 82°N latitude, Geophys. Res. Lett., 13, 113–116, 1986. Bottenheim, J W., Barrie, L A., Atlas, E., Heidt, L E., Niki, H., Rasmussen, R A., and Shepson, P B.: Depletion of lower tropospheric ozone during Arctic spring: The polar sunrise experiment 1988, J. Geophys. Res., 95, 18 555–18 568, 1990. Bottenheim, J W., Dibb, J E., Honrath, R E., and Shepson, P B.: An introduction to the Alert 2000 and Summit 2000 Arctic research studies, Atmos. Environ., 36, 2467–2469, 2002a. Bottenheim, J W., Fuentes, J D., Tarasick, D W., and Anlauf, K G.: Ozone in the Arctic Lower Troposphere During Winter and Spring 2000 (ALERT2000), Atmos. Environ., 36, 2535–2544, 2002b. Cho, H., Shepson, P B., Barrie, L A., Cowin, J P., and Zaveri, R.: NMR investigation of the Quasi-Brine Layer in Ice/Brine Mixtures, J. Phys. Chem. B, 106, 11 226–11 232, 2002. Cicerone, R J., Heidt, L E., and Pollack, W H.: Measurements of atmospheric methyl-bromide and bromoform, J. Geophys. Res., 93, 3745–3749, 1988. Covert, D S. and Heintzenberg, J.: Size distributions and chemical properties of aerosol at Ny-Alesund, Svalbard, Atmos. Environ., 27A, 2989–2997, 1993. Curry, J A.: Interactions among Turbulence, Radiation and Microphysics in Arctic Stratus Clouds, J. Atmos. Sci., 43, 90–106, 1986. de~Serves, C.: Gas phase formaldehyde and peroxide measurements in the Arctic atmosphere, J. Geophys. Res., 99, 25 391–25 398, 1994. Dethleff, D.: Polynyas as a possible source for enigmatic Bennett Island atmospheric plumes, American Geophysical Union, Geophysical Monograph, 85, 1994. Dominé, F., Taillandier, A S., Simpson, W R., and Severin, K.: Specific surface area, density and microstructure of frost flowers, Geophys. Res. Lett., 32, 1–4, 2005. Drinkwater, M R. and Crocker, G B.: Modelling changes in the dielectric and scattering properties of young snow-covered sea ice at GHz frequencies, J. Glaciol., 34, 274–282, 1988. Eigen, M. and Kustin, K.: The kinetics of halogen hydrolysis, J. Am. Chem. Soc., 84, 1355–1361, 1962. Evans, M J., Jacob, D J., Atlas, E., Cantrell, C A., Eisele, F., Flocke, F., Fried, A., Mauldin, R L., Ridley, B A., Wert, B., Walega, J., Weinheimer, A., Blake, D., Heikes, B., Snow, J., Talbot, R., and Dibb, J.: Coupled evolution of \chemBrO_x-\chemClO_x-HO_x-NO_x, chemistry during bromine-catalyzed ozone depletion events in the arctic boundary layer, J. Geophys. Res., 108, D4, doi:10.1029/2002JD002732, 2003. Fan, S.-M. and Jacob, D J.: Surface ozone depletion in Arctic spring sustained by bromine reactions on aerosols, Nature, 359, 522–524, 1992. 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, 23 719–23 727, 1999. Foster, K L., Plastridge, R A., Bottenheim, J W., Shepson, P B., Finlayson-Pitts, B J., and Spicer, C W.: The Role of \chemBr_2 and \chemBrCl in Surface Ozone Destruction at Polar Sunrise, Science, 291, 471–473, 2001. Fuhrer, K., Hutterli, M., and McConnell, J R.: Overview of recent field experiments for the study of the air-snow transfer of \chemH_2O_2 and \chemHCHO, in: Chemical Exchange Between the Atmosphere and Polar Snow, edited by: Springer-Verlag, New York, publisher: NATO ASI Series, volume 43, pp. 307–318, 1996. Georgiadis, T., Bonafé, U., Calzolari, F., Nardino, M., Orsini, A., Pirazzini, R., Ravegnani, F., Sozzi, R., Trivellone, G., and Argentini, S.: Study of the surface energy balance at Ny-Alesund, Svalbard, Conference Proceedings – Italian Physical Society, 69, 163–174, 2000. Ghosal, S., Shbeeb, A., and Hemminger, J C.: Surface Segregation of Bromine doped \chemNaCl: Implications for the Seasonal Variations in Arctic Ozone, Geophys. Res. Lett., 27, 1879–1882, 2000. Ghosal, S., Hemminger, J C., Bluhm, H., Mun, B S., Hebenstreit, E. L D., Ketteler, G., Ogletree, D F., Requejo, F G., and Salmeron, M.: Electron Spectroscopy of Aqueous Solution Interfaces Reveals Surface Enhancement of Halides, Science, 307, 563–566, 2005. Gloersen, P. and Campbell, W J.: Recent variations in Arctic and Antarctic sea-ice covers, Nature, 352, 33–36, \doi10.1038/352033a0, 1991. Grannas, A M., Jones, A E., Dibb, J., Amman, M., Anastasio, C., Ariya, P., Beine, H J., Bergin, M., Bottenheim, J., Boxe, C S., Carver, G., Chen, G., Crawford, J H., Dominé, F., Frey, M M., Guzmán, M I., Heard, D E., Helmig, D., Hoffmann, M R., Honrath, R E., Huey, L G., Hutterli, M., Jacobi, H.-W., Klán, P., McConnell, J., Sander, R., Savarino, J., Shepson, P B., Simpson, W R., Sodeau, J R., von Glasow, R., Weller, R., Wolff, E., and Zhu, T.: Snow Photochemistry: Current State of the Science, Atmos. Chem. Phys. Discuss., in press, 2007. Hafskjold, B., Ikeshojit, T., and Ratkjes, S K.: On the molecular mechanism of thermal diffusion in liquids, Mol. Phys., 80, 1389–1412, 1993. Hartmann, J., Kottmeier, C., and Raasch, S.: Roll Vortices and Boundary Layer Development during a Cold Air Outbreak, vol 84, Springer Netherlands, 1997. Hartmann, J., Albers, F., Argentini, S., Borchert, A., Bonafé, U., Cohrs, W., Conidi, A., Freese, D., Georgiadis, T., Ippoliti, A., Kaleschke, L., Lüpkes, C., Maixner, U., Mastrantonio, G., Ravegnani, F., Reuter, A., Trivellone, G., and Viola, A.: Reports on Polar Research. Arctic Radiation and Turbulence Interaction Study (ARTIST), 1999. Hausmann, M. and Platt, U.: Spectroscopic measurement of bromine oxide and ozone in the high Arctic during Polar Sunrise Experiment 1992, J. Geophys. Res., 99, 25 399–25 413, 1994. Herman, G. and Goody, R.: Formation and Persistence of Summertime Arctic Stratus Clouds, J. Atmos. Sci., 33, 1537–1553, 1976. Hoff, R M., Leaitch, W R., Fellin, P., and Barrie, L A.: Mass Size Distributions of Chemical Constituents of the Winter Arctic Aerosol, J. Geophys. Res., 88, 10 947–10 956, 1983. Hollwedel, J., Wenig, M., Beirle, S., Kraus, S., Kühl, S., Wilms-Grabe, W., Platt, U., and Wagner, T.: Year-to-Year Variability of Polar Tropospheric \chemBrO as seen by GOME, Adv. Space Res., 34, 804–808, 2004. Hönninger, G. and Platt, U.: Observations of \chemBrO and its vertical distribution during surface ozone depletion at Alert, Atmos. Environ., 36, 2481–2489, 2002. Hönninger, G., Leser, H., Sebastián, O., and Platt, U.: Ground-based measurements of halogen oxides at the Hudson Bay by longpath DOAS and passive MAX-DOAS, Geophys. Res. Lett., 31, L04 111, doi:10.1029/2003GL018 982, 2004. Honrath, R E., Peterson, M C., Guo, S., Dibb, J E., Shepson, P B., and Campbell, B.: Evidence of NO_x Production Within or Upon Ice Particles in the Greenland Snowpack, Geophys. Res. Lett., 26, 695–698, 1999. Honrath, R E., Guo, S., Peterson, M C., Dziobak, M P., Dibb, J E., and Arsenault, M A.: Photochemical production of gas phase NO_x from ice crystal \chemNO_3^-, J. Geophys. Res., 105, 24 183–24 190, 2000a. Honrath, R E., Peterson, M C., Dziobak, M P., Dibb, J E., Arsenault, M A., and Green, S A.: Release of NO_x from Sunlight-irradiated Midlatitude Snow, Geophys. Res. Lett., 27, 2237–2240, 2000b. Hopper, J F. and Hart, W.: Meteorological aspects of the 1992 Polar Sunrise Experiment, J. Geophys. Res., 99, 25 315–25 328, \doi10.1029/94JD02400, 1994. Hopper, J F., Peters, B., Yokouchi, Y., Niki, H., Jobson, B T., Shepson, P B., and Muthuramu, K.: Chemical and meteorological observations at ice camp SWAN during Polar Sunrise Experiment 1992, J. Geophys. Res., 99, 25 489–25 498, 1994. Hopper, J F., Barrie, L A., Silis, A., Hart, W., Gallant, A J., and Dryfhout, H.: Ozone and meteorology during the 1994 Polar Sunrise Experiment, J. Geophys. Res., 103, 1481–1492, 1998. Hutterli, M A., Röthlisberger, R., and Bales, R C.: Atmosphere-to-snow-to-firn transfer studies of \chemHCHO at Summit, Greenland, Geophys. Res. Lett., 26, 1691–1694, 1999. Hutterli, M A., Connell, J. R M., Stewart, R W., Jacobi, H.-W., and Bales, R C.: Impact of temperature-driven cycling of hydrogen peroxide (\chemH_2O_2) between air and snow on the planetary boundary layer, J. Geophys. Res., 106, 15 393–15 404, 2001. Jacobi, H.-W., Frey, M M., Hutterli, M A., Bales, R C., Schrems, O., Cullen, N J., Steffen, K., and Koehler, C.: Measurements of hydrogen peroxide and formaldehyde exchange between the atmosphere and surface snow at Summit, Greenland, Atmos. Environ., 36, 2619–2628, 2002. Jacobi, H.-W., Bales, R C., Honrath, R E., Peterson, M C., Dibb, J E., Swanson, A L., and Albert, M R.: Reactive trace gases measured in the interstitial air of surface snow at Summit, Greenland, Atmos. Environ., 38, 1687–1697, 2004. Jacobi, H.-W., Kaleschke, L., Richter, A., Rozanov, A., and Burrows, J P.: Observation of a Fast Ozone Loss in the Marginal ice Zone of the Arctic Ocean, J. Geophys. Res., 111, D15309, doi:10.1029/2005JD006715, 2006. Jobson, B T., Niki, H., Yokouchi, Y., Bottenheim, J., Hopper, F., and Leaitch, R.: Measurements of \chemC_2-\chemC_6 hydrocarbons during the Polar Sunrise 1992 Experiment: Evidence for \chemCl atom and \chemBr atom chemistry, J. Geophys. Res., 99, 25 355–25 368, 1994. Jones, A E., Weller, R., Wolff, E W., and Jacobi, H.-W.: Speciation and Rate of Photochemical \chemNO and \chemNO_2 Production in Antarctic Snow, Geophys. Res. Lett., 27, 345–348, 2000. Jones, A E., Weller, R., Anderson, P S., Jacobi, H.-W., Wolff, E W., Schrems, O., and Miller, H.: Measurements of NO_x emissions from the Antarctic snowpack, Geophys. Res. Lett., 28, 1499–1502, 2001. Jungwirth, P. and Tobias, D J.: Ions at the Air/Water Interface, J. Phys. Chem. B, 106, 6361–6373, 2002. Kaleschke, L., Richter, A., Burrows, J., Afe, O., Heygster, G., Notholt, J., Rankin, A M., Roscoe, H K., Hollwedel, J., Wagner, T., and Jacobi, H.-W.: Frost flowers on sea ice as a source of sea salt and their influence on tropospheric halogen chemistry, Geophys. Res. Lett., 31, L16114, doi:10.1029/2004GL020655, 2004. Kempers, L. J. T M.: A thermodynamic theory of the Soret effect in a multicomponent liquid, J. Chem. Phys., 90, 6541–6548, 1989. Khalil, M. A K. and Rasmussen, R A.: Statistical analysis of trace gases in Arctic haze, Geophys. Res. Lett., 11, 437–440, 1984. Kieser, B N., Bottenheim, J W., Sideris, T., and Niki, H.: Spring 1989 observations of lower tropospheric chemistry in the canadian high arctic, Atmos. Environ., 27A, 2979–2988, 1993. King, J C. and Turner, J.: Antarctic Meteorology and Climatology, Atmospheric and Space Science Series, 1997. Kirchner, U., Benter, T., and Schindler, R N.: Experimental verification of gas phase bromine enrichment in reactions of \chemHOBr with sea salt doped ice surfaces, Ber. Bunsenges. Phys. Chem., 101, 975–977, 1997. Koop, T., Kapilashrami, A., Molina, L T., and Molina, M J.: Phase transitions of sea-salt/water mixtures at low temperatures: Implications for ozone chemistry in the polar marine boundary layer, J. Geophys. Res., 105, 26 393–26 402, 2000. Kreher, K., Johnston, P V., Wood, S W., Nardi, B., and Platt, U.: Ground-based measurements of tropospheric and stratospheric \chemBrO at Arrival Heights, Antarctica, Geophys. Res. Lett., 24, 3021–3024, 1997. Landgraf, J. and Crutzen, P.: An Efficient Method for `On-Line' Calculations of Photolysis and Heating Rates, J. Atmos. Sci., 55, 863–878, 1998. Langendörfer, U., Lehrer, E., Wagenbach, D., and Platt, U.: Observation of filterable bromine variabilities during Arctic tropospheric ozone depletion events in high (1 hour) time resolution, J. Atmos. Chem., 34, 39–54, 1999. Le~Bras, G. and Platt, U.: A possible mechanism for combined chlorine and bromine catalyzed destruction of tropospheric ozone in the Arctic, Geophys. Res. Lett., 22, 599–602, 1995. Leaitch, W R., Barrie, L A., Bottenheim, J W., and Li, S M.: Airborne observations related to ozone depletion at polar sunrise, J. Geophys. Res., 99, 25 499–25 517, 1994. Legagneux, L., Cabanes, A., and Dominé, F.: Measurement of the specific surface area of 176 snow samples using methane adsorption at 77K, J. Geophys. Res., 107(D17), 4335; doi:10.1029/2001JD001016, 2002. Lehrer, E., Wagenbach, D., and Platt, U.: Aerosol chemical composition during tropospheric ozone depletion at Ny-Alesund/Svalbard, Tellus, 49B, 486–495, 1997. Lehrer, E., Hönninger, G., and Platt, U.: A one dimensional model study of the mechanism of halogen liberation and vertical transport in the polar troposphere, Atmos. Chem. Phys., 4, 2427–2440, 2004. Lelieveld, J. and Crutzen, P J.: Influences of cloud photochemical processes on tropospheric ozone, Nature, 343, 227–233, 1990. Li, S.-M.: Equilibrium of particle nitrite with gas phase \chemHONO: Tropospheric measurements in the high Arctic during polar sunrise, J. Geophys. Res., 99, 25 469–25 478, 1994. MacDowall, J.: Some observations at Halley Bay in seismology, glaciology and meteorology, Proc. Roy. Soc., 256, 149–192, 1960. Marion, G M.: Carbonate mineral solubility at low temperatures in the \chemNa-\chemK-\chemMg-\chemCa-\chemH-\chemCl-\chemSO_4-\chem% OH-\chemHCO_3-\chemCO_3-\chemCO_2-\chemH_2O system, Geochim. Cosmochim. Acta, 65, 1883–1896, 2001. Martin, S., Drucker, R., and Fort, M.: A laboratory study of frost flower growth on the surface of young sea-ice, J. Geophys. Res., 100, 7027–7036, 1995. Martinez, M., Arnold, T., and Perner, D.: The role of bromine and chlorine chemistry for arctic ozone depletion events in Ny-Alesund and comparison with model calculations, Ann. Geophys., 17, 941–956, 1999. McConnell, J C., Henderson, G S., Barrie, L., Bottenheim, J., Niki, H., Langford, C H., and Templeton, E. M J.: Photochemical bromine production implicated in Arctic boundary-layer ozone depletion, Nature, 355, 150–152, 1992. Michalowski, B A., Francisco, J S., Li, S.-M., Barrie, L A., Bottenheim, J W., and Shepson, P B.: A computer model study of multiphase chemistry in the Arctic boundary layer during polar sunrise, J. Geophys. Res., 105, 15 131–15 145, 2000. Mickle, R E., Bottenheim, J W., Leaitch, W R., and Evans, W.: Boundary layer ozone depletion during AGASP-II, Atmos. Environ., 23, 2443–2449, 1989. Mitchell, J. M J.: Visual range in the polar regions with particular reference to the alaskan Arctic, J. Atmos. Terr. Phys., Spec. Suppl., 1, 195–211, 1957. Monahan, E C., Spiel, D E., and Davidson, K L.: A model of marine aerosol generation via whitecaps and wave disruption, in: Oceanic Whitecaps, edited by: Monahan, E C. and Niocaill, G M., pp. 167–174, D. Reidel, Norwell, Mass, 1986. Moortgat, G K., Meller, R., and Schneider, W.: Temperature dependence (256–296 K) of the absorption cross sections of bromoform in the wavelength range 285–360 nm, in: Tropospheric Chemistry of Ozone in Polar Regions, NATO ASI Ser, Subser 1: Global Environmental Change, edited by: Niki, H. and Becker, K H., pp. 359–370, Springer Verlag, New York, 1993. Morales~Maqueda, M A., Willmott, A J., and Biggs, N. R T.: Polynyas dynamics: A review of observations and modeling, Rev. Geophys., 42, 1–37, 2004. Mozurkewich, M.: Mechanisms for the release of halogens from sea-salt particles by free radical reactions, J. Geophys. Res., 100, 14 199–14 207, 1995. Oltmans, S J.: Surface ozone measurements in clean air, J. Geophys. Res., 86, 1174–1180, 1981. Oltmans, S J. and Komhyr, W.: Surface ozone distributions and variations from 1973–1984 measurements at the NOAA Geophysical Monitoring for Climate Change Baseline observatories, J. Geophys. Res., 91, 5229–5236, 1986. Papadimitriou, S., Kennedy, H., Kattner, G., Dieckmann, G S., and Thomas, D N.: Experimental evidence for carbonate precipitation and \chemCO_2 degassing during sea ice formation, Geochim. Cosmochim. Acta, 68, 1749–1761, 2003. Perovitch, D K. and Richter-Menge, J A.: Surface characteristics of lead ice, J. Geophys. Res., 99, 16 341–16 350, 1994. Peterson, M C. and Honrath, R E.: Observations of Rapid Photochemical Destruction of Ozone in Snowpack Interstitial Air, Geophys. Res. Lett., 28, 511–514, 2001. Platt, U.: DOAS-measurements during the ARCTOC campaigns 1995 and 1996 in Ny Alesund/Svalbard, ARCTOC final report, 1997. Platt, U. and Lehrer, E.: Arctic Tropospheric Ozone Chemistry, ARCTOC, Final Report of the EU-Project NO. EV5V-CT93-0318, 1996. Pruppacher, H R. and Klett, J D.: Microphysics of Clouds and Precipitation, Kluwer Academic Pub., Dordrecht/Boston/London, 1997. Ramacher, B., Rudolph, J., and Koppmann, R.: Hydrocarbon measurements during tropospheric ozone depletion events: Evidence for halogen atom chemistry, J. Geophys. Res., 104, 3633–3653, 1999. Rankin, A M., Auld, V., and Wolff, E W.: Frost flowers as a source of fractionated sea salt aerosol in the polar regions, Geophys. Res. Lett., 27, 3469–3472, 2000. Rankin, A M., Wolff, E W., and Martin, S.: Frost flowers: Implications for tropospheric chemistry and ice core interpretation, J. Geophys. Res., 107, 4683, doi:10.1029/2002JD002492, 2002. Richardson, C. and Keller, E E.: The brine content of sea ice measured with a nuclear magnetic resonance spectrometer, J. Glaciol., 6, 89–100, 1966. Richter, A., Wittrock, F., Eisinger, M., and Burrows, J P.: GOME Observations of Tropospheric \chemBrO in Northern Hemispheric Spring and Summer 1997, Geophys. Res. Lett., 25, 2683–2686, 1998. Ridley, B A., Walega, J., Montzka, D., Grahek, F., Atlas, E., Flocke, F., Stroud, V., Deary, J., Gallant, A., Boudries, H., Bottenheim, J., Anlauf, K., Worthy, D., Sumner, A L., Splawn, B., and Shepson, P.: Is the Arctic Surface Layer a Source and Sink of NO_x in Winter/Spring?, J. Atmos. Chem., 36, 1–22, 2000. Ridley, B A., Atlas, E L., Montzka, D D., Browell, E V., Cantrell, C A., Blake, D R., Blake, N J., Cinquini, L., Coffey, M T., Emmons, L K., Cohen, R C., DeYoung, R J., Dibb, J E., Eisele, F L., Flocke, F M., Fried, A., Grahek, F E., Grant, W B., Hair, J W., Hannigan, J., Heikes, B J., Lefer, B L., Mauldin, R L., Moody, J L., Shetter, R E., Snow, J A., Talbot, R W., Thornton, J A., Walega, J G., Weinheimer, A J., Wert, B P., and Wimmers, A J.: Ozone Depletion Events Observed in the High Latitude Surface Layer During the TOPSE Aircraft Program, J. Geophys. Res., 108, D4, doi:10.1029/2001JD001507, 2003. Roscoe, H K. and Roscoe, J.: Polar tropospheric ozone depletion events observed in the International Geophysical Year of 1958, Atmos. Chem. Phys., 6, 3303–3314, 2006. Roscoe, H K., Kreher, K., and Friess, U.: Ozone loss episodes in the free Antarctic troposphere, suggesting a possible climate feedback, Geophys. Res. Lett., 28, 2911–2914, 2001. Sander, R., Vogt, R., Harris, G W., and Crutzen, P J.: Modeling the chemistry of ozone, halogen compounds, and hydrocarbons in the arctic troposphere during spring, Tellus, 49B, 522–532, 1997. 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. Sander, R., Burrows, J., and Kaleschke, L.: Carbonate precipitation in brine – a potential trigger for tropospheric ozone depletion events, Atmos. Chem. Phys., 6, 4653–4658, 2006. Saw, G E.: Microparticle size spectrum of Arctic haze, Geophys. Res. Lett., 11, 409–412, 1984. Serreze, M C. and Barry, R G.: The Arctic Climate System, Cambridge University Press, 2005. Simpson, W R., Alvarez-Aviles, L., Douglas, T A., Sturm, M., and Dominé, F.: Halogens in the coastal snow pack near Barrow, Alaska: Evidence for active bromine air-snow chemistry during springtime, Geophys. Res. Lett., 32, L04811, doi:10.1029/2004GL021748, 2005. Simpson, W R., Carlson, D., Hönninger, G., Douglas, T A., Sturm, M., Perovich, D., and Platt, U.: First-year sea-ice contact predicts bromine monoxide (\chemBrO) levels at Barrow, Alaska better than potential frost flower contact, Atmos. Chem. Phys., 7, 621–627, 2007. Snow, J A., Heikes, B G., Merrill, J T., Wimmers, A J., Moody, J L., and Cantrell, C A.: Winter-spring evolution and variability of HOx reservoir species, hydrogen peroxide and methyl hydroperoxide, in the northern mid to high-latitudes, J. Geophys. Res., 108(D4), doi:10.1029/2002JD002172, 2002. Spicer, C W., Plastridge, R A., Foster, K L., Finlayson-Pitts, B J., Bottenheim, J W., Grannas, A M., and Shepson, P B.: Molecular halogens before and during ozone depletion events in the Arctic at polar sunrise: concentrations and sources, Atmos. Environ., 36, 2721–2731, 2002. Staebler, R M., den Hartog, G., Georgi, B., and Düsterdiek, T.: Aerosol size distributions in Arctic haze during the Polar Sunrise Experiment 1992, J. Geophys. Res., 99, 25 429–25 437, 1994. Stroud, C., Madronich, S., Atlas, E., Ridley, B., Flocke, F., Weinheimer, A., Talbot, B., Fried, A., Wert, B., Shetter, R., Lefer, B., Coffey, M., Heikes, B., and Blake, D.: Photochemistry in the arctic free troposphere: NO_x budget and the role of odd nitrogen reservoir recycling, Atmos. Environ., 37, 3351–3364, 2003. Strunin, M A., Postnov, A A., and Mezrin, M Y.: Meteorological potential for contamination of arctic troposphere: Boundary layer structure and turbulent diffusion characteristics, Atmos. Res., 44, 37–51, 1997. Sturges, W T., Cota, G F., and Buckley, P T.: Bromoform emission from Arctic ice algae, Nature, 358, 660–662, 1992. Sumner, A L. and Shepson, P B.: Snowpack production of formaldehyde and its effect on the Arctic troposphere, Nature, 398, 230–233, 1999. Swanson, A L., Blake, N J., Dibb, J E., Albert, M R., Blake, D R., and Rowland, F S.: Photochemically induced production of \chemCH_3Br, \chemCH_3I, \chemC_2H_5I, ethene, and propene within surface snow at Summit, Greenland, Atmos. Environ., 36, 2671–2682, 2002. Tang, T. and McConnell, J C.: Autocatalytic release of bromine from Arctic snow pack during polar sunrise, Geophys. Res. Lett., 23, 2633–2636, 1996. Tarasick, D W. and Bottenheim, J W.: Surface Ozone Depletion Episodes in the Arctic and Antarctic from Historical Ozonesonde Records, Atmos. Chem. Phys., 2(3), 197–205, 2002. Tuckermann, M., Ackermann, R., Gölz, C., Lorenzen-Schmidt, H., Senne, T., Stutz, J., Trost, B., Unold, W., and Platt, U.: DOAS-observation of halogen radical-catalysed arctic boundary layer ozone destruction during the ARCTOC-campaigns 1995 and 1996 in Ny-Alesund, Spitsbergen, Tellus, 49B, 533–555, 1997. Vogt, R., Crutzen, P J., and Sander, R.: A mechanism for halogen release from sea-salt aerosol in the remote marine boundary layer, Nature, 383, 327–330, 1996. von Glasow, R. and Crutzen, P J.: Model study of multiphase DMS oxidation with a focus on halogens, Atmos. Chem. Phys., 4, 589–608, 2004. von Glasow, R. and Sander, R.: Variation of sea salt aerosol pH with relative humidity, Geophys. Res. Lett., 28, 247–250, 2001. 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, 2002a. 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, D17, doi:10.1029/2001JD000942, 2002b. Wagenbach, D., Ducroz, F., Mulvaney, R., Keck, L., Minikin, A., Legrand, M., Hall, J S., and Wolff, E W.: Sea-salt aerosol in coastal Antarctic regions, J. Geophys. Res., 103, 10 961–10 974, 1998. Wagner, T. and Platt, U.: Observation of Tropospheric BrO from the GOME satellite, Nature, 395, 486–490, 1998. Wagner, T., Leue, C., Wenig, M., Pfeilsticker, K., and Platt, U.: Spatial and temporal distribution of enhanced boundary layer \chemBrO concentrations measured by the GOME instrument aboard ERS-2, J. Geophys. Res., 106, 24 225–24 235, 2001. Wolff, E W., Jones, A E., Martin, T J., and Grenfell, T C.: Modelling photochemical NO_x production and nitrate loss in the upper snowpack of Antarctica, Geophys. Res. Lett., 29, 1944, doi:10.1029/2002GL015823, 2002. Worthy, D. E J., Trivett, N. B A., Hopper, J F., and Bottenheim, J.: Analysis of long-range transport events at Alert, Northwest Territories, during the Polar Sunrise Experiment, J. Geophys. Res., 99, 25 329–25 344, 1994. Zhang, K J., Briggs, M E., Gammon, R W., and Sengers, J V.: Optical measurement of the Soret coefficient and the diffusion coefficient of liquid mixtures, J. Chem. Phys., 90, 6541–6548, 1996. Zhou, X., Beine, H J., Honrath, R E., Fuentes, J D., Simpson, W., Shepson, P B., and Bottenheim, J W.: Snowpack Photochemical production of \chemHONO: A Major Source of \chemOH in the Arctic Boundary Layer in Springtime, Geophys. Res. Lett., 28, 4087–4090, 2001.