ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-9-515-2009 Meridional transport and deposition of atmospheric <sup>10</sup>Be Heikkilä U. 1 Beer J. 1 Feichter J. 2 EAWAG, Überlandstrasse 133, 8600 Dübendorf, Switzerland Max-Planck Institute for Meteorology, Hamburg, Germany 23 01 2009 9 2 515 527 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/9/515/2009/acp-9-515-2009.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/9/515/2009/acp-9-515-2009.pdf

<sup>10</sup>Be concentrations measured in ice cores exhibit larger temporal variability than expected based on theoretical production calculations. To investigate whether this is due to atmospheric transport a general circulation model study is performed with the <sup>10</sup>Be production divided into stratospheric, tropospheric tropical, tropospheric subtropical and tropospheric polar sources. A control run with present day <sup>10</sup>Be production rate is compared with a run during a geomagnetic minimum. The present <sup>10</sup>Be production rate is 4–5 times higher at high latitudes than in the tropics whereas during a period of no geomagnetic dipole field it is constant at all latitudes. The <sup>10</sup>Be deposition fluxes, however, show a very similar latitudinal distribution in both the present day and the geomagnetic minimum run indicating that <sup>10</sup>Be is well mixed in the atmosphere before its deposition. This is also confirmed by the fact that the contribution of <sup>10</sup>Be produced in the stratosphere is dominant (55%–70%) and relatively constant at all latitudes. The contribution of stratospheric <sup>10</sup>Be is approximately 70% in Greenland and 60% in Antarctica reflecting the weaker stratosphere-troposphere air exchange in the Southern Hemisphere.

 References Bard, E., Raisbeck, G., Yiou, F., and Jouzel, J.: Solar modulation of cosmogenic nuclide production over the last millennium: comparison between $^14$C and $^10$Be records, Earth and Planetary Science Letters, 150, 453–462, 1997. Baumgartner, S., Beer, J., Masarik, J., Wagner, G., Meynadier, L., and Synal, H.-A.: Geomagnetic Modulation of the $^36$Cl flux in the GRIP ice core, Greenland, Science, 279, 1330–1332, 1998. Beer, J., Andrée, M., Oeschger, H., Siegenthaler, U., Bonani, G., Hofmann, H., Morenzoni, E., Nessi, M., Suter, M., Wölfli, W., Finkel, R., and Langway, Jr. C.: The Camp Century $^10$Be ice core record: implications for long-term variations of the geomagnetic dipole moment, Nucl. Instrum. Meth., B5, 380–384, 1984. Beer, J., Bonani, G., Hofmann, H., Suter, M., Synal, H. A., Wölfli, W., Oescher, H., Siegenthaler, U., and Finkel, R.: $^10$Be measurements on polar ice: comparison of Arctic and Antarctic records, Nucl. Instrum. Meth., B29, 380–384, 1987. Beer, J., Siegenthaler, U., and Blinov, A.: Temporal $^10$Be variations in ice: information on solar activity and geomagnetic field intensity, Secular Solar and Geomagnetic Variartions in the Last 10'000 Years, by Kluwer Academic Publishers, 297–313, 1988. Beer, J., McCracken, K., Abreu J., Heikkilä, U., and Steinhilber, F.: Long–term changes in cosmic rays derived from cosmogenic radionuclides, ICRC 2007 Proceedings, Merida, Mexico, 2007. Field, C., Schmidt, G., Koch, D. and Salyk, C.: Modeling production and climate-related impacts on $^10$Be concentration in ice cores, J. Geophys. Res., 111, D15107, doi:10.1029/2005JD00640, 2006. Heikkilä, U.: Modelling of the atmospheric transport of the cosmogenic radionuclides $^10$Be and $^7$Be using the ECHAM5-HAM general circulation model, Dissertation ETH No. 17516, online available at: http://e-collection.ethbib.ethz.ch, 2007. Heikkilä, U., Beer, J., and Feichter, J.: Modeling cosmogenic radionuclides $^10$Be and $^7$Be during the Maunder Minimum with the general circulation model ECHAM5–HAM, Atmos. Chem. Phys., 8, 2797–2809, 2008a. Heikkilä, U., Beer, J., Jouzel, J., Feichter, J., and Kubik, P.: $^10$Be measured in a GRIP snow pit and modeled using the ECHAM5–HAM general circulation model, Geophys. Res. Lett., 35, L05817, doi:10.1029/2007GL033067, 2008b. Holton, J., Haynes, P., McIntyre, M., Douglass, A., Rood, R., and Pfister, L.: Stratosphere-troposphere exchange, Rev. Geophys., 33, 403–439, 1995. Lal, D. and Peters, B., Cosmic ray produced radioactivity on the Earth, Handbuch der Physik, Springer-Verlag, New York, USA, XLVI/2, 551–612, 1967. Masarik, J. and Beer, J.: Simulation of particle fluxes and cosmogenic nuclide production in the Earth's atmosphere, J. Geophys. Res., 104, 12099–12111, 1999. Mazaud, A., Laj, C., and Bender, M.: A geomagnetic chronology for antarctic ice accumulation, Geophys. Res. Lett., 21(5), 337–340, 1994. McCracken, K., McDonald, F., Beer, J., Raisbeck, G., and Yiou, F.: A phenomenological study of the long–term cosmic ray modulation, 850–1958 AD, J. Geophys. Res. 109, A12103, doi:1029/2005JA10685, 2004a. McCracken, K.: Geomagnetic and atmospheric effects upon the cosmogenic $^10$Be observed in polar ice, J. Geophys. Res., 109, A04101, doi:10.1029/2003JA010060, 2004b. Muscheler, R., Joos, F., Beer, J., Müller, S., Vonmoos, M., and Snowball, I.: Solar activity during the last 1000 yr inferred from radionuclide records, Quarternary Sci. Rev., 26, 82–97, 2007. Pedro, J., van Ommen, T., Curran, M., Morgan, V., Smith, A., and McMorrow, A.: Evidence for climate modulation of $^10$Be solar activity proxy, J. Geophys. Res., 111, D21105, doi:10.1029/2005JD006764, 2006. Raisbeck, G., Yiou, F., Bourles, D., Lorius, C., Jouzel, J. and Barkov, N. I.: Evidence for two intervals of enhanced $^10$Be deposition in Antarctic ice during the last glacial period, Nature, 326, 273–277, 1987. Roeckner, E., Baeuml, G., Bonventura, L., Brokopf, R., Esch, M., Giorgetta, M., Hagemann, S., Kirchner, I., Kornblueh, L., Manzini, E., Rhodin, A., Schlese, U., Schulzweida, U., and Tompkins, A.: The atmospheric general circulation model ECHAM5. PART I: Model description, Report 349, Max Planck Institute for Meteorology, Hamburg, Germany, online available at: http://www.mpimet.mpg.de, 2003. Steig, E., Polissar, P., Stuiver, M., Grootes, P., and Finkel, R.: Large amplitude solar modulation cycles of $^10$Be in Antractica: implications for atmospheric mixing processes and interpretation of the ice core record, Geophys. Res. Lett., 23(5), 523–526, 1996. Stier, P., Feichter, J., Kinne, S., Kloster, S., Vignati, E., and Wilson, J.: Ganzeveld., L., Tegen, I., Werner, M., Schulz, M., Balkanski, Y., Boucher, O., Minikin, A., and Petzold, A.: The aerosol–climate model ECHAM5-HAM, Atmos. Chem. Phys., 5, 1125–1165, 2005. Stohl, A., Bonasoni, P., Cristofanelli, P., Collins, W., Feichter, J., Frank, A., Forster, C., Gerasopoulos, E., Gäggeler, H., James, P., Kentarchos, T., Kromp-Kolb, H., Krüger, B., Land, C., Meloen, J., Papayannis, A., Priller, A., Seibert, P., Sprenger, M., Roelofs, G. J., Scheel, H. E., Schnabel, C., Siegmund, P., Tobler, L., Trickl, T., Wernli, H., Wirth, V., Zanis, P., Zerefos, C.: Stratosphere-troposphere exchange: A review, and what we have learnt from STACCATO, J. Geophys. Res., 108(D12), 8516, doi:10.1029/2002JD002490, 2003. Textor, C., Schulz, M., Guibert, S., Kinne, S., Balkanski, Y., Bauer, S., Berntsen, T., Berglen, T., Boucher, O., Chin, M., Dentener, F., Diehl, T., Easter, R., Feichter, J., Fillmore, D., Ghan, S., Ginoux, P., Gong, S., Grini, A., Hendricks, J., Horowitz, L., Huang, P., Isaksen, I., Iversen, T., Kloster, S., Koch, D., Kirkev\aa g, A., Kristjansson, J. E., Krol, M., Lauer, A., Lamarque, J. F., Liu, X., Montanaro, V., Myhre, G., Penner, J., Pitari, G., Reddy, S., Seland, \O., Stier, P., Takemura, T. and Tie, X.: Analysis and quantification of the diversities of aerosol life cycles within AeroCom, Atmos. Chem. Phys., 6, 1777–1813, 2006. Timmreck, C., Graf, H.-F., and Feichter, J.: Simulation of Mt. Pinatubo volcanic aerosol with the Hamburg Climate Model ECHAM4, Theor. Appl. Climatol., 62, 85–108, 1999. Usoskin, I. G., Alanko–Huotari, K., Kovaltsov, G. A., and Mursula., K.: Heliospheric modulation of cosmic rays: Monthly reconstruction of 1951–2004, J. Geophys. Res. 110, A12108, doi:10.1029/2005JA011250, 2005. Vonmoos, M., Beer, J., and Muscheler, R.: Large variations in Holocene solar activity: Constraints from $^10$Be in the Greenland Ice Core Project ice core, J. Geophys. Res., 111, A10105, doi:10.1029/2005JA011500, 2006. Yiou, F., Raisbeck, G. M., Bourles, D., Lorius, C., and Barkov, N. I.: $^10$Be in ice at Vostok Antarctica during the last climatic cycle, Nature, 316, 616–617, 1985.