ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-11-2697-2011 Cosmic rays, aerosol formation and cloud-condensation nuclei: sensitivities to model uncertainties Snow-Kropla E. J. 1 Pierce J. R. 1 Westervelt D. M. 2 Trivitayanurak W. 2 3 Dalhousie University, Halifax, Nova Scotia, Canada Carnegie Mellon University, Pittsburgh, Pennsylvania, USA now at: Department of Highways, Bangkok, Thailand 24 01 2011 11 1 2697 2732 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-discuss.net/11/2697/2011/acpd-11-2697-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/11/2697/2011/acpd-11-2697-2011.pdf

The flux of cosmic rays to the atmosphere has been observed to correlate with cloud and aerosol properties. One proposed mechanism for these correlations is the "ion-aerosol clear-air" mechanism where the cosmic rays modulate atmospheric ion concentrations, ion-induced nucleation of aerosols and cloud condensation nuclei (CCN) concentrations. We use a global chemical transport model with online aerosol microphysics to explore the dependence of CCN concentrations on the cosmic-ray flux. Expanding upon previous work, we test the sensitivity of the cosmic-ray/CCN connection to several uncertain parameters in the model including primary emissions, Secondary Organic Aerosol (SOA) condensation and charge-enhanced condensational growth. The sensitivity of CCN to cosmic rays increases when simulations are run with decreased primary emissions, but show location-dependent behavior from increased amounts of secondary organic aerosol and charge-enhanced growth. For all test cases, the change in the concentration of particles larger than 80 nm between solar minimum (high cosmic ray flux) and solar maximum (low cosmic ray flux) simulations is less than 0.2%. The change in the total number of particles larger than 10 nm was larger, but always less than 1%. The simulated change in the column-integrated Ångström exponent was negligible for all test cases. Additionally, we test the predicted aerosol sensitivity to week-long Forbush decreases of cosmic rays and find that the maximum change in aerosol properties for these cases is similar to steady-state aerosol differences between the solar maximum and solar minimum. These results provide evidence that the effect of cosmic rays on CCN and clouds through the ion-aerosol clear-sky mechanism is limited by dampening from aerosol processes.

 References Adams, P. J. and Seinfeld, J. H.: Predicting global aerosol size distributions in general circulation models, J. Geophys. Res., 107, 4370, doi:10.1029/2001JD001010, 2002. Bohren, C. F. and Huffman, D. R.: Absorption and Scattering of Light by Small Particles, Wiley, New York, 544 pp., 1998. Bondo, T., Enghoff, M. B., and Svensmark, H.: Model of optical response of marine aerosols to Forbush decreases, Atmos. Chem. Phys., 10, 2765–2776, doi:10.5194/acp-10-2765-2010, 2010. Bricard, J.: Action of radioactivity and of pollution upon parameters of atmospheric electricity, in: Problems of atmospheric and space electricity, edited by: Coroniti, S. C., Elsevier Publishing Company, New York, 83–117, 1965. Calogovic, J., Albert, C., Arnold, F., Beer, J., Desorgher, L., and Flueckiger, E. O.: Sudden cosmic ray decreases: No change of global cloud cover, Geophys. Res. Lett., 37, L03802, doi:10.1029/2009GL041327, 2010. Carslaw, K. S., Harrison, R. G., and Kirkby, J.: Cosmic rays, Clouds, and Climate, Science, 298, 1732–1737, doi:10.1126/science.1076964, 2002. Forster, P., Ramaswamy, V., Artaxo, P., Berntsen, T., Betts, R., Fahey, D. W., Haywood, J., Lean, J., Lowe, D. C., Myhre, G., Nganga, J., Prinn, R., Raga, G., Schulz, M., and Van Dorland, R.: Changes in atmospheric constituents and in radiative forcing, in Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M., and Miller, H. L., 229–234, Cambridge Univ. Press, Cambridge, UK, 2007. Harrison, R. G. and Stephenson, D. B.: Empirical evidence for a nonlinear effect of galactic cosmic rays on clouds, P. Roy. Soc. A-Math. Phy., 462, 1221–1233, ISI:000235973800009, 2006. Jimenez, J. L., Canagaratna, M. R., Donahue, N. M., Prevot, A. S. H., Zhang, Q., Kroll, J. H., DeCarlo, P. F., Allan, J. D., Coe, H., Ng, N. L., Aiken, A. C., Docherty, K. S., Ulbrich, I. M., Grieshop, A. P., Robinson, A. L., Duplissy, J., Smith, J. D., Wilson, K. R., Lanz, V. A., Hueglin, C., Sun, Y. L., Tian, J., Laaksonen, A., Raatikainen, T., Rautiainen, J., Vaattovaara, P., Ehn, M., Kulmala, M., Tomlinson, J. M., Collins, D. R., Cubison, M. J., Dunlea, J., Huffman, J. A., Onasch, T. B., Alfarra, M. R., Williams, P. I., Bower, K., Kondo, Y., Schneider, J., Drewnick, F., Borrmann, S., Weimer, S., Demerjian, K., Salcedo, D., Cottrell, L., Griffin, R., Takami, A., Miyoshi, T., Hatakeyama, S., Shimono, A., Sun, J. Y., Zhang, Y. M., Dzepina, K., Kimmel, J. R., Sueper, D., Jayne, J. T., Herndon, S. C., Trimborn, A. M., Williams, L. R., Wood, E. C., Middlebrook, A. M., Kolb, C. E., Baltensperger, U., and Worsnop, D. R.: Evolution of organic aerosols in the atmosphere, Science, 326, 1525–1529. 2009. Kanakidou, M., Seinfeld, J. H., Pandis, S. N., Barnes, I., Dentener, F. J., Facchini, M. C., Van Dingenen, R., Ervens, B., Nenes, A., Nielsen, C. J., Swietlicki, E., Putaud, J. P., Balkanski, Y., Fuzzi, S., Horth, J., Moortgat, G. K., Winterhalter, R., Myhre, C. E. L., Tsigaridis, K., Vignati, E., Stephanou, E. G., and Wilson, J.: Organic aerosol and global climate modelling: a review, Atmos. Chem. Phys., 5, 1053–1123, doi:10.5194/acp-5-1053-2005, 2005. Kim, D. and Ramanathan, V.: Solar radiation budget and radiative forcing due to aerosols and clouds, J. Geophys. Res., 113, D02203, doi:10.1029/2007JD008434, 2008. Kristjansson, J. E., Kristiansen, J., and Kaas, E.: Solar activity, cosmic rays, clouds and climate – an update, Adv. Space Res., 34, 407–415, 2004. Kulmala, M., Vehkamäki, H., Petäjä, T., Dal Maso, M., Lauri, A., Kerminen, V. M., Birmili, W., and McMurry, P. H.: Formation and growth rates of ultrafine atmospheric particles: a review of observations, J. Aerosol Sci., 35, 143–176, 2004. Kuang, C., McMurry, P. H., and McCormick, A. V.: Determination of cloud condensation nuclei production from measured new particle formation events, Geophys. Res. Lett., 36, L09822, doi:10.1029/2009GL037584, 2009. Marsh, N. D. and Svensmark, H.: Cosmic rays, clouds, and climate, Space Sci. Rev., 94, 215–230, ISI:000165631400021, 2000a. Marsh, N. D. and Svensmark, H.: Low cloud properties influenced by cosmic rays, Phys. Rev. Lett., 85, 5004–5007, ISI:000165612100042, 2000b. Modgil, M. S., Kumar, S., Tripathi, S. N., and Lovejoy, E. R.: A parameterization of ion-induced nucleation of sulphuric acid and water for atmospheric conditions, J. Geophys. Res., 110, D19205, ISI:000232687000001, 2005. Nadykto, A. B. and Yu, F.: Uptake of neutral polar vapor molecules by charged clusters/particles: Enhancement due to dipole-charge interaction, J. Geophys. Res., 108, 4717, doi:10.1029/2003JD003664, 2003. Penner, J., Andreae, M. O., Annegarn, H., Barrie, L. A., Feichter, J., Hegg, D., Jayaraman, A., Leaitch, R., Murphy, D. M., Nganga, J., and Pitari, G.: Aerosols, their direct and indirect effects, in: Climate Change 2001: The Science Basis, edited by: Nyenzi, B. and Prospero, J. M., Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 289–348, 2001. Pierce, J. R. and Adams, P. J.: Efficiency of cloud condensation nuclei formation from ultrafine particles, Atmos. Chem. Phys., 7, 1367–1379, doi:10.5194/acp-7-1367-2007, 2007. Pierce, J. R. and Adams, P. J.: Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates?, Geophys. Res. Lett., 36, L09820, doi:10.1029/2009GL037946, 2009a. Pierce, J. R. and Adams, P. J.: Uncertainty in global CCN concentrations from uncertain aerosol nucleation and primary emission rates, Atmos. Chem. Phys., 9, 1339–1356, doi:10.5194/acp-9-1339-2009, 2009b. Sun, B. M. and Bradley, R. S.: Solar influences on cosmic rays and cloud formation: A reassessment, J. Geophys. Res., 107, 4211, ISI:000178977300018, 2002. Svensmark, H. and Friis-Christensen, E.: Variation of cosmic ray flux and global cloud coverage – A missing link in solar-climate relationships, J. Atmos. Sol.-Terr. Phys., 59, 1225–1232, ISI:A1997XD89500001, 1997. Svensmark, H., Bondo, T., and Svensmark, J.: Cosmic ray decreases affect atmospheric aerosols and clouds, Geophys. Res. Lett., 36, L15101, doi:10.1029/2009GL038429, 2009. Tinsley, B. A. and Heelis, R. A.: Correlations of Atmospheric Dynamics With Solar Activity Evidence for a Connection via the Solar Wind, Atmospheric Electricity, and Cloud Microphysics, J. Geophys. Res., 98(D6), 10375–10384, doi:10.1029/93JD00627, 1993. Todd, M. C. and Kniveton, D. R.: Changes in cloud cover associated with Forbush decreases of galactic cosmic rays, J. Geophys. Res., 106, 32031–32041, ISI:000173479100030, 2001. Todd, M. C. and Kniveton, D. R.: Short-term variability in satellite-derived cloud cover and galactic cosmic rays: an update, J. Atmos. Sol.-Terr. Phys., 66, 1205–1211, ISI:000223560300013, 2004. Usoskin, I. G. and Kovaltsov, G. A.: Cosmic ray induced ionization in the atmosphere: Full modeling and practical applications, J. Geophys. Res., 111, D21206, doi:10.1029/2006JD007150, 2006. Yu, F.: Altitude variations of cosmic ray induced production of aerosols: Implications for global cloudiness and climate, J. Geophys. Res., 107(A7), 1118, doi:10.1029/2001JA000248, 2002. Yu, F.: From molecular clusters to nanoparticles: second-generation ion-mediated nucleation model, Atmos. Chem. Phys., 6, 5193–5211, doi:10.5194/acp-6-5193-2006, 2006. Yu, F.: Ion-mediated nucleation in the atmosphere: Key controlling parameters, implications, and look-up table, J. Geophy. Res., 115, D03206, doi:10.1029/2009JD012630, 2010. Yu, F. and Luo, G.: Simulation of particle size distribution with a global aerosol model: contribution of nucleation to aerosol and CCN number concentrations, Atmos. Chem. Phys., 9, 7691–7710, doi:10.5194/acp-9-7691-2009, 2009. Yu, F., Luo, G., Bates, T., Anderson, B., Clarke, A., Kapustin, V., Yantosca, R., Wang, Y., and Wu, S.: Spatial distributions of particle number concentrations in the global troposphere: Simulations, observations, and implications for nucleation mechanisms, J. Geophys. Res., 115, D17205, doi:10.1029/2009JD013473, 2010. Trivitayanurak, W., Adams, P. J., Spracklen, D. V., and Carslaw, K. S.: Tropospheric aerosol microphysics simulation with assimilated meteorology: model description and intermodel comparison, Atmos. Chem. Phys., 8, 3149–3168, doi:10.5194/acp-8-3149-2008, 2008.