ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-10367-2011 Modelling of sea salt concentrations over Europe: key uncertainties and comparison with observations Tsyro S. 1 Aas W. 2 Soares J. 3 Sofiev M. 3 Berge H. 1 Spindler G. 4 Norwegian Meteorological Institute, P.O. Box 43, Blindern, 0313, Oslo, Norway Norwegian Institute for Air Research, P.O. Box 100, 2027, Kjeller, Norway Finnish Meteorological Institute, P.O. Box 503, 00101, Helsinki, Finland Leibniz Institute for Tropospheric Research, Permoserstraße 15, 04318, Leipzig, Germany 18 10 2011 11 20 10367 10388 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/11/10367/2011/acp-11-10367-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/10367/2011/acp-11-10367-2011.pdf

Sea salt aerosol can significantly affect the air quality. Sea salt can cause enhanced concentrations of particulate matter and change particle chemical composition, in particular in coastal areas, and therefore should be accounted for in air quality modelling. We have used an EMEP Unified model to calculate sea salt concentrations and depositions over Europe, focusing on studying the effects of uncertainties in sea salt production and lifetime on calculation results. Model calculations of sea salt have been compared with EMEP observations of sodium concentrations in air and precipitation for a four year period, from 2004 to 2007, including size (fine/coarse) resolved EMEP intensive measurements in 2006 and 2007. In the presented calculations, sodium air concentrations are between 8% and 46% overestimated, whereas concentrations in precipitation are systematically underestimated by 65–70% for years 2004–2007. A series of model tests have been performed to investigate the reasons for this underestimation, but further studies are needed. The model is found to reproduce the spatial distribution of Na<sup>+</sup> in air and precipitation over Europe fairly well, and to capture most of sea salt episodes. The paper presents the main findings from a series of tests in which we compare several different sea spray source functions and also look at the effects of meteorological input and the efficiency of removal processes on calculated sea salt concentrations. Finally, sea salt calculations with the EMEP model have been compared with results from the SILAM model and observations for 2007. While the models produce quite close results for Na<sup>+</sup> at the majority of 26 measurement sites, discrepancies in terms of bias and temporal correlation are also found. Those differences are believed to occur due to differences in the representation of source function and size distribution of sea salt aerosol, different meteorology used for model runs and the different models' resolution. This study contributes to getting a better insight on uncertainties associated with sea salt calculations and thus facilitates further improvement of aerosol modelling on both regional and global scales.

 References Andreas, E. L.: A new sea spray generation function for wind speeds up to 32 m s<sup>−1</sup>, J. Phys. Oceanogr., 28, 2175–2184, 1998. Andreas, E. L., Pattison, M. J., and Belcher, S. E.: Production rates of sea-spray droplets, in: Clarification and elaboration, edited by: Pattison, M. J. and Belcher, S. E., J. Geophys. Res., 106, C4, 7157–7161, 2001. Athanasopoulou, E., Tombrou, M., Pandis, S. N., and Russell, A. G.: The role of sea-salt emissions and heterogeneous chemistry in the air quality of polluted coastal areas, Atmos. Chem. Phys., 8, 5755–5769, http://dx.doi.org/10.5194/acp-8-5755-2008doi:10.5194/acp-8-5755-2008, 2008. Berge, H.: Implementation and evaluation of a parameterisation of coarse nitrate, Master Thesis in Geoscience, Meteorology and Oceanography, University of Oslo, Department of Geoscience, Oslo, Norway, 2009. Blomqvist, G. and Johansson, E.-L.: Airborne spreading and deposition of de-icing salt – a case study, The Science of The Total Environment, 235, 161–168, 1999. Clarke, A. D., Owens, S. R., and Zhou, J.: An ultrafine sea-salt flux from breaking waves: Implications for cloud condensation nuclei in the remote marine atmosphere, J. Geophys. Res., 111, D06202, http://dx.doi.org/10.1029/2005JD006565doi:10.1029/2005JD006565, 2006. de Leeuw, G., Neele, F. P., Hill, M., Smith, M. H., and Vignati, E.: Production of sea spray aerosol in the surf zone, J. Geophys. Res., 105, 29397–29409, 2000. EC DIRECTIVE 2008/50/EC of the european parliament and of the council of 21 May 2008 on ambient air quality and cleaner air for Europe: http://ec.europa.eu/environment/air/legis.htm, 2008 EMEP/CCC: Manual for sampling and chemical analysis, Revised November 2001. Norwegian Institute for Air Research Kjeller, EMEP/CCC-Report 1/95, URL: http://tarantula.nilu.no/projects/ccc/manual/index.html, 1995. Fagerli, H., Simpson, D., and Tsyro, S.: Unified EMEP model: Updates, in Transboundary acidification, eutrophication and ground level ozone in Europe. EMEP Status Report 1/2004, 11–18, Norwegian Meteorological Institute, Oslo, Norway, 2004. Foltescu, V. L., Pryor, S. C., and Bennet, C.: Sea salt generation and removal on the regional scale, Atmos. Environ., 39, 2123–2133, 2004. Garratt, J. R.: The atmospheric boundary layer. Cambridge University Press, 1992. Geever, M., O'Dowd, C. D., van Ekeren, S., Flanagan, R., Nilsson, E. D., de Leeuw, G., and Rannik, U.: Submicron sea spray fluxes, Geophys. Res. Lett., 32, L15810, http://dx.doi.org/10.1012/2005GL023081doi:10.1012/2005GL023081, 2005. Gerber, H. E.: Relative-humidity parameterisation of the Navy aerosol model (NAM), NRL Rep. 8956, Natl., Res. Lab., Washington DC, USA, 1985. Grini, A., Myhre, G., Sundet, J. K. and Isaksen, I. S. A.: Modelling the annual cycle of sea salt in the global 3-D model OSLO CTM-2, Concentrations, fluxes, and radiative impact, J. Clim., 15, 1717–1730, 2002. Gong, S. L.: A parameterisation of sea-salt aerosol source function for sub- and super-micron particles, Global Biogeochem. Cy., 17, 1097, http://dx.doi.org/10.1029/2003GB002079doi:10.1029/2003GB002079, 2003. Gong, S. L., Barrie, L. A., and Blanchet, J.-P.: Modeling sea-salt aerosols in the atmosphere: 1, Model development, J. Geophys. Res., 102, 3805–3818, 1997a. Gong, S. L., Barrie, L. A., Prospero, J. M., Savoie, D. L., Ayers, G. P., Blanchet, J.-P., and Spacek, L.: Modeling sea-salt aerosols in the atmosphere: 2. Atmospheric concentrations and fluxes, J. Geophys. Res., 102, 3819–3830, 1997b. Gong, S. L., Barrie, L. A., and Lazare, M.: Canadian Aerosol Module(CAM): A size-segregated simulation of atmospheric aerosol processes for climate and air quality models, 2. Global sea-salt aerosol and its budgets, J. Geophys. Res., 107, 4779, http://dx.doi.org/10.1029/2001GB002004doi:10.1029/2001GB002004, 2002. Guelle, W., Schulz, M., Balkanski, Y., and Dentener, F.: Influence of the source formulation on modeling atmospheric global distribution of sea salt aerosol, J. Geophys. Res., 106, 27509–27524, 2001. Hellsten, S., van Loon, M., Tarrason, L., Vestreng, V., Tørseth, K., Kindbom, K., and Aas, W.: Base cations deposition in Europe, IVL Report B1722, Swedish Environmental Research Institute, Stockholm, http://www3.ivl.se/rapporter/pdf/B1722.pdf, 2007. Hoppel, W. A., Frick, G. M., and Fitzgerald, J. W.: Surface source function for sea-salt aerosol and aerosol dry deposition to the ocean surface, J. Geophys. Res., 107, 4382, doi:10.1029/2001JD002014, 2002. Hjellbrekke, A.-G. and Fjæraa, A. M.: Data Report 2007 Acidifying and eutrophying compounds and particulate matter, EMEP/CCC-Report 1/2009, Norwegian Institute for Air Research, Kjeller, 2009. Langmann, B., Varghese, S., Marmer, E., Vignati, E., Wilson, J., Stier, P., and O'Dowd, C.: Aerosol distribution over Europe: a model evaluation study with detailed aerosol microphysics, Atmos. Chem. Phys., 8, 1591–1607, http://dx.doi.org/10.5194/acp-8-1591-2008doi:10.5194/acp-8-1591-2008, 2008. Lewis, E. R. and Schwartz, S. E.: Sea Salt Aerosol Production: Mechanisms, Methods, Measurements, and Models: A Critical Review, American Geophysical Union, Washington, DC, USA, 2004. Liu, H., Crawford, J. H., Pierce, R. B., Norris, P., Yantosca, R. M., Evans, M. J., Kittaka, C., Feng, J., and Tie, X: Radiative effect of clouds on tropospheric chemistry in a global three-dimensional chemical transport model, J. Geophys. Res., 111, D20303, http://dx.doi.org/10.1029/2005JD006403doi:10.1029/2005JD006403, 2006. Ma, X., von Salzen, K., and Li, J.: Modelling sea salt aerosol and its direct and indirect effects on climate, Atmos. Chem. Phys., 8, 1311–1327, http://dx.doi.org/10.5194/acp-8-1311-2008doi:10.5194/acp-8-1311-2008, 2008. Maykut, N., Lewtas, J., Kim, E. and Larson, T. V.: Source apportionment of PM$_2.5$ at an urban IMPROVE site in Seattle, Washington, Envir. Sci. Tech., 37, 5135–5142, 2003. Millero, F. J.: Physicochemical controls on seawater, in: Treatise on Geochemistry, edited by: Holland, H. D. and Turkian, K. K., Elsevier, Amsterdam, The Netherlands, 2004. Monahan E. C. and O'Muircheartaigh, I.: Optimal power-law description of oceanic whitecap coverage dependence on wind speed, J. Phys. Oceanogr., 10, 2094–2099, 1980. Monahan, E. G., 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. and Niocaill, G. M., 167–174, D. Reidel, Norwell, Mass., 1986. Mårtensson, E. M., Tunved, P. Korhonen, H., and Nilsson, E. D.: Are submicrometer sea salt emission parameterisations consistent with observed remote marine aerosol distributions?, in: Submicrometre aerosol emissions from sea spray and road traffic, Doctoral Thesis in Atmospheric Science, Stockholm University, Sweden, 2007. Mårtensson, E. M., Nilsson, E. D., de Leeuw, G., Cohen, L. H., and Hansson, H.-C.: Laboratory simulations and parameterisation of the primary marine aerosol production, J. Geophys. Res., 108, p 4297, http://dx.doi.org/10.1029/2002JD002263doi:10.1029/2002JD002263, 2003. %Nilsson, E. D., Mårtensson, E. M., Van Ekeren, J. S., de Leeuw, G., %Moerman, M., and O'Dowd, C.: Primary marine aerosol emissions: size resolved %eddy covariance measurements with estimates of the sea salt and organic %carbon fractions. Atmos. Chem. Phys. Discuss., 7, 13345-13400, 2007. Nilsson, E. D., Mårtensson, E. M., Van Ekeren, J. S., de Leeuw, G., Moerman, M., and O'Dowd, C.: Primary marine aerosol emissions: size resolved eddy covariance measurements with estimates of the sea salt and organic carbon fractions, Atmos. Chem. Phys. Discuss., 7, 13345–13400, http://dx.doi.org/10.5194/acpd-7-13345-2007doi:10.5194/acpd-7-13345-2007, 2007. O'Dowd, C. D., Smith, M. H., Costerdine, I. E., and Lowe, J. A.: Marine aerosol, sea salt, and the marine sulphur cycle: A short review, Atmos. Environ., 32, 73–80, 1997. Ooki, A., Uematsu, M., Miura, K., and Nakae, S.: Sources of sodium in atmospheric fine particles, Atmos. Environ., 36, 4367–4374, 2002. Pierce, J. and Adams, P. J.: Global evaluation of CCN formation by direct emission of sea salt and growth of ultrafine sea salt, J. Geophys. Res., 111, D06203, http://dx.doi.org/10.1029/2005JD006186doi:10.1029/2005JD006186, 2006. Pryor, S. C., Barthelmie, R, J., Schoof, J. T., Binkowski, F. S., Delle Monache, L., and Stull, R.: Modeling the impact of sea-spray on particle concentrations in a coastal city, Sci. Total Environ., 391, 132–142, 2007. Schulz, M., de Leeuw, G., and Balkanski, Y.: Sea salt aerosol source functions and emissions, in: Emissions of Atmospheric Trace Components, edited by: Granier, C., Artaxo, P., and Reeves, C., 333–359, Kluwer Academic Publishers, Dordrecht, The Netherlands, 2004. Sellegri, K., Gourdeau, J., Putaud, J. P. and Despiau, S.: Chemical composition of marine aerosol in a Mediterranean coastal zone during the FETCH experiment, J. Geophys. Res., 106, 12023–12037, 2001. Simpson, D., Fagerli, H., Jonson, J. E., Tsyro, S., Wind, P., and Tuovinen, J.-P.: Transboundary Acidification, Eutrophication and Ground Level Ozone in Europe, Part I. Unified EMEP Model Description, EMEP/MSC-W Status report 1/2003 Part~I, Norwegian Meteorological Institute, Oslo, Norway, http://www.emep.int., 2003, Smith, M. H. and Harrison, N. M.: The sea spray generation function, J. Aerosol Sci., 29, 189–190, 1998. Smith, M. H., Park, P. M., and Consterdine, I. E.: Marine aerosol concentrations and estimated fluxes over sea, Q. J. R. Meteorol. Soc., 119, 809–824, 1993. Sofiev M., Siljamo, P., Valkama, I., Ilvonen, M., and Kukkonen, J.: A dispersion modelling system SILAM and its evaluation against ETEX data, Atmos. Environ., 40, 674–685, DOI:10.1016/j.atmosenv.2005.09.069, 2006. Sofiev, M., Soares, J. Prank, M. de Leeuw, G., and Kukkonen, J.: A regional-to-global model of emission and transport of sea salt particles in the atmosphere, in press, 2011. Stier, P., Feichter, J., Kinne, S., Kloster, S., Vignati, E., Wilson, J., Ganzeveld, L., Tegen, I., Werner, M., Balkanski, Y., Schulz, M., Boucher, O., Minikin, A., and Petzold, A.: The aerosol-climate model ECHAM5-HAM, Atmos. Chem. Phys., 5, 1125-1156, http://dx.doi.org/10.5194/acp-5-1125-2005doi:10.5194/acp-5-1125-2005, 2005. Stull, R. B.: An Introduction to Boundary Layer Meteorology, Atmospheric Science Library, Kluwer Academic Publishers, 1988. Tsyro, S.: Regional Model for Formation, Dynamics, and Long-range Transport of Atmospheric Aerosol. Russian Meteorology and Hydrology, ISSN 1068–3739, 33, 2, 82–90, 2008. Tsyro, S., Berge, H., Benedictow, A., and Gauss, M.: Studying the effect of meteorological input on Unified EMEP model results. In: Transboundary acidification, eutrophication and ground level ozone in Europe in 2008, EMEP Status Report 1/2010, Norwegian Meteorological Institute, Oslo, Norway, http://www.emep.int., 2010, van Loon, M., Tarrasón, L. and Posch, M.: Modelling Base Cations in Europe, MSC-W Technical Report 2/05, Norwegian Meteorological Institute, Oslo, Norway, 2005. Uggerud, H. and Hjellbrekke, A.-G.: The twenty-sixth intercomparison of analytical methods within EMEP, Norwegian Institute for Air Research, Kjeller, EMEP/CCC-Report 6/2009, 2009. van den Berg, A., Dentener, F., and Lelieveld, J.: Modeling the chemistry of the marine boundary layer: Sulphate formation and the role of sea-salt aerosol particles, J. Geophys. Res., 105, 11,671–11,698, http://dx.doi.org/10.1029/1999JD901073doi:10.1029/1999JD901073, 2000. Vignati, E., de Leeuw, G., and Berkowicz, R.: Modeling coastal aerosol transport and effects of surf-produced aerosols on process in the marine atmospheric boundary layer, J. Geophys. Res., 105, D17, 20,225–20,238, 2001. White, W. H.: Chemical markers for sea salt in IMPROVE aerosol data, Atmos. Environ., 42, 261–274, 2008. Zakey, A. S., Giorgi, F., and Bi, X.: Modelling of se salt in a regional climate model: Fluxes and radiative forcing, J. Geophys. Res., 113, D14221, http://dx.doi.org/10.1029/2007JD009209doi:10.1029/2007JD009209, 2008.