ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-11175-2011 Rate of non-linearity in DMS aerosol-cloud-climate interactions Thomas M. A. 1 3 Suntharalingam P. 1 Pozzoli L. 2 7 Devasthale A. 3 Kloster S. 4 5 Rast S. 5 Feichter J. 5 Lenton T. M. 1 6 School of Environmental Sciences, University of East Anglia, Norwich, UK European Commission, Joint Research Centre, Institute for Environment and Sustainability, Ispra, Italy Swedish Meteorological and Hydrological Institute, Norrkoping, Sweden Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA Department of Atmospheric Sciences, Max-Planck-Institute for Meteorology, Hamburg, Germany Department of Geography, University of Exeter, Exeter, Devon, UK now at: Eurasia Institute of Earth Sciences, Istanbul Technical University, Istanbul, Turkey 10 11 2011 11 21 11175 11183 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/11/11175/2011/acp-11-11175-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/11175/2011/acp-11-11175-2011.pdf

The degree of non-linearity in DMS-cloud-climate interactions is assessed using the ECHAM5-HAMMOZ model by taking into account end-to-end aerosol chemistry-cloud microphysics link. The evaluation is made over the Southern oceans in austral summer, a region of minimal anthropogenic influence. In this study, we compare the DMS-derived changes in the aerosol and cloud microphysical properties between a baseline simulation with the ocean DMS emissions from a prescribed climatology, and a scenario where the DMS emissions are doubled. Our results show that doubling the DMS emissions in the current climate results in a non-linear response in atmospheric DMS burden and subsequently, in SO<sub>2</sub> and H<sub>2</sub>SO<sub>4</sub> burdens due to inadequate OH oxidation. The aerosol optical depth increases by only ~20 % in the 30° S–75° S belt in the SH summer months. This increases the vertically integrated cloud droplet number concentrations (CDNC) by 25 %. Since the vertically integrated liquid water vapor is constant in our model simulations, an increase in CDNC leads to a reduction in cloud droplet radius of 3.4 % over the Southern oceans in summer. The equivalent increase in cloud liquid water path is 10.7 %. The above changes in cloud microphysical properties result in a change in global annual mean radiative forcing at the TOA of −1.4 W m<sup>−2</sup>. The results suggest that the DMS-cloud microphysics link is highly non-linear. This has implications for future studies investigating the DMS-cloud climate feedbacks in a warming world and for studies evaluating geoengineering options to counteract warming by modulating low level marine clouds.

 References Albrecht, B.: Aerosols, cloud microphysics and fractional cloudiness, Science, 245, 1227–1230, 1989. Auvray, M., Bey, I., Llull, E., Schultz, M G., and Rast, S.: A model investigation of tropospheric ozone chemical tendencies in long-range transported pollution plumes, J. Geophys. Res., 112, D05304, doi:10.1029/2006JD007137, 2007. Boucher, O. and Lohmann, U.: The sulfate-CCN-cloud albedo effect, Tellus, 47B, 281–300, 1994. Boucher, O., Moulin, C., Belviso, S., Aumont, O., Bopp, L., Cosme, E., von Kuhlmann, R., Lawrence, M. G., Pham, M., Reddy, M S., Sciare2, J., and Venkataraman, C.: DMS atmospheric concentrations and sulphate aerosol indirect radiative forcing: a sensitivity study to the D MS source representation and oxidation, Atmos. Chem. Phys., 3, 49–65, http://dx.doi.org/10.5194/acp-3-49-2003doi:10.5194/acp-3-49-2003, 2003. Boyd, P W.: Ranking geo-engineering schemes, Nature Geosci., 1, 722–724, 2008. Carslaw, K. S., Boucher, O., Spracklen, D. V., Mann, G. W., Rae, J. G. L., Woodward, S., and Kulmala, M.: A review of natural aerosol interactions and feedbacks within the Earth system, Atmos. Chem. Phys., 10, 1701–1737, http://dx.doi.org/10.5194/acp-10-1701-2010doi:10.5194/acp-10-1701-2010, 2010. Chuang, C C. and Penner, J E.: Effects of anthropogenic sulfate on cloud drop nucleation and optical properties, Tellus, 47B, 566–577, 1995. Feichter, J., Kjellstrom, E., Rodhe, H., Dentener, F., Lelieveld, J., and Roelofs, G.: Simulation of the tropospheric sulfur cycle in a global climate model, Atmos. Environ., 30, 1693–1707, 1996. Gondwe, M., Krol, M., Gieskes, W., Klaassen, W., and de~Baar, H.: The contribution of ocean-leaving DMS to the global atmospheric burdens of DMS, MSA, SO<sub>2</sub>, and nssSO<sub>4</sub>=, Global Biogeochem. Cy., 17, 1056, doi:10.1029/2002GB001937, 2003. Jones, A., Haywood, J., and Boucher, O.: Climate impacts of geoengineering marine stratocumulus clouds, J. Geophys. Res., 114, D10106, doi:10.1029/2008JD011450, 2009. Kettle, A. and Andreae, M.: Flux of dimethylsulfide from the oceans: A comparison of updated data sets and flux models, J. Geophys. Res., 105, 26793–26808, 2000. Khairoutdinov, M. and Kogan, Y.: A new cloud physics parameterization in a large-eddy simulation model of marine stratocumulus, Mon. Weather Rev., 128, 229–243, 2000. Korhonen, H., Carslaw, K. S., and Romakkaniemi, S.: Enhancement of marine cloud albedo via controlled sea spray injections: a global model study of the influence of emission rates, microphysics and transport, Atmos. Chem. Phys., 10, 4133–4143, http://dx.doi.org/10.5194/acp-10-4133-2010doi:10.5194/acp-10-4133-2010, 2010. Latham, J., Rasch, P., Chen, C.-C., Kettles, L., Gadian, A., Gettelman, A., Morrison, H., Bower, K., and Choularton, T.: Global temperature stabilization via controlled albedo enhancement of low-level maritime clouds, Philos. T. R. Soc. A, 366, 3969–3987, 2008. Lohmann, U. and Feichter, J.: Impact of sulfate aerosols on albedo and lifetime of clouds: A sensitivity study with the ECHAM4 GCM, J. Geophys. Res., 102, 13685–13700, 1997. Lohmann, U. and Feichter, J.: Global indirect aerosol effects: a review, Atmos. Chem. Phys., 5, 715–737, http://dx.doi.org/10.5194/acp-5-715-2005doi:10.5194/acp-5-715-2005, 2005. Lohmann, U., Feichter, J., Chuang, C C., and Penner, J E.: Predicting the number of cloud droplets in the ECHAM GCM, J. Geophys. Res., 104, 9169–9198, 1999. Lohmann, U., Stier, P., Hoose, C., Ferrachat, S., Kloster, S., Roeckner, E., and Zhang, J.: Cloud microphysics and aerosol indirect effects in the global climate model ECHAM5-HAM, Atmos. Chem. Phys., 7, 3425–3446, http://dx.doi.org/10.5194/acp-7-3425-2007doi:10.5194/acp-7-3425-2007, 2007. Monahan, E., Spiel, D., and Davidson, K.: Oceanic whitecaps and their role in air-sea exchange, chapter: A model of marine aerosols generation via whitecaps and wave disruption, D. Reidel, Norwell, Massachusetts, USA, 252 ed., 167–174, 1986. Nightingale, P D., Malin, G., Law, C S., Liss, A. J. W. P S., Liddicoat, M I., Boutin, J., and Upstill-Goddard, R C.: In situ evaluation of air-sea gas exchange parameterizations using novel conservative and volatile tracers, Global Biogeochem. Cy., 14, 373–388, 2000. Pandis, S N., Russell, L M., and Seinfeld, J H.: The relationship between DMS flux and CCN concentrations in remote marine regions, J. Geophys. Res., 99, 16945–16957, 1994. Peng, Y. and Lohmann, U.: Sensitivity study of the spectral dispersion of the cloud droplet size distribution on the indirect aerosol effect, Geophys. Res. Lett, 30, 1507, http://dx.doi.org/10.1029/2003GL017192doi:10.1029/2003GL017192, 2003. Pozzoli, L.: Climate and chemistry interactions: Development and evaluation of a coupled chemistry-aerosol-climate model, PhD thesis, Ecole Polytech. Fed. de Lausanne, Lausanne, Switzerland, 2007. Pozzoli, L., Bey, I., Rast, J S., Schultz, M G., Stier, P., and Feichter, J.: Trace gas and aerosol interactions in the fully coupled model of aerosol-chemistry-climate ECHAM5-HAMMOZ: 1. Model description and insights from the spring 2001 TRACE-P experiment, J. Geophys. Res., 113, D07308, doi:10.1029/2007JD009007, 2008a. Pozzoli, L., Bey, I., Rast, J S., Schultz, M G., Stier, P., and Feichter, J.: Trace gas and aerosol interactions in the fully coupled model of aerosol-chemistry-climate ECHAM5-HAMMOZ: 2. Impact of heterogeneous chemistry on the global aerosol distributions, J. Geophys. Res., 113, D07309, doi:10.1029/2007JD009008, 2008b. Quaas, J., Ming, Y., Menon, S., Takemura, T., Wang, M., Penner, J. E., Gettelman, A., Lohmann, U., Bellouin, N., Boucher, O., Sayer, A. M., Thomas, G. E., McComiskey, A., Feingold, G., Hoose, C., Kristjánsson, J. E., Liu, X., Balkanski, Y., Donner, L. J., Ginoux, P. A., Stier, P., Grandey, B., Feichter, J., Sednev, I., Bauer, S. E., Koch, D., Grainger, R. G., Kirkevåg, A., Iversen, T., Seland, Ø., Easter, R., Ghan, S. J., Rasch, P. J., Morrison, H., Lamarque, J.-F., Iacono, M. J., Kinne, S., and Schulz, M.: Aerosol indirect effects –general circulation model intercomparison and evaluation with satellite data, Atmos. Chem. Phys., 9, 8697–8717, http://dx.doi.org/10.5194/acp-9-8697-2009doi:10.5194/acp-9-8697-2009, 2009. Rasch, P J., Latham, J., and Chen, C C.: Geoengineering by cloud seeding: Influence on sea ice and climate system., Environ. Res. Lett., 4, 8 pp., 2009. Rast, S., Schultz, M G., Aghedo, A M., Bey, I., Brasseur, G P., Diehl, T., Esch, M., Ganzeveld, L., Kirchner, I., Kornblueh, L., Rhodin, A., Roeckner, E., Schmidt, H., Schroeder, S., Schulzweida, U., Stier, P., and van Noije, T.: Evaluation of the tropospheric chemistry general circulation model ECHAM5-MOZ and its application to the analysis of the interannual variability in tropospheric ozone from 1960-2000, chemical composition of the trosposphere for the period 1960-2000 (RETRO), MPI-Reports on Earth System Science, in preparation, 2011. Russell, L M., Pandis, S N., and Seinfeld, J H.: Aerosol production and growth in the marine boundary layer, J. Geophys. Res., 99, 20989–21003, 1994. Salter, S., Sortino, G., and Latham, J.: Sea-going hardware for the cloud albedo method of reversing global warming., Phil. Trans.R. Soc., A366, 3989–4006, 2008. Smith, M. and Harrison, N.: The sea spray generation function, J. Aerosol Sci., 29, 189–190, 1998. Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K., Tignor, M., and Miller, H. L. (eds.): IPCC, 2007: Summary for Policymakers, 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., Cambridge University Press, Cambridge, UK and New York, NY, USA, 2007. Stier, P., Feichter, J., Kinne, S., Kloster, S., Vignati, E., Wilson, J., Ganzeveld, T., 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, 1125–1165, http://dx.doi.org/10.5194/acp-5-1125-2005doi:10.5194/acp-5-1125-2005, 2005. Thomas, M A., Suntharalingam, P., Pozzoli, L., Rast, S., Devasthale, A., Kloster, S., Feichter, J., and Lenton, T M.: Quantification of DMS aerosol-cloud-climate interactions using the ECHAM5-HAMMOZ model in a current climate scenario, Atmos. Chem. Phys., 10, 7425–7438, http://dx.doi.org/10.5194/acp-10-7425-2010doi:10.5194/acp-10-7425-2010, 2010. Tompkins, A M.: A prognostic parameterization for the subgrid-scale variability of water vapor and clouds in large-scale models and its use to diagnose cloud cover, J. Atmos. Sci., 59, 1917–1942, 2002. Twomey, S A.: Pollution and the Planetary Albedo, Atmos. Environ., 8, 1251–1256, 1974. Twomey, S A.: The influence of pollution on the shortwave albedo of clouds, J. Atmos. Sci., 34, 1149–1152, 1977. Wingenter, O W., Haase, K B., Strutton, P., Friederich, G., Meinardi, S., Blake, D R., and Roland, F S.: Changing concentrations of CO, CH<sub>4</sub>, C$_5$H$_8$, CH<sub>3</sub>Br, CH<sub>3</sub>I, and dimethyl sulfide during the Southern Ocean Iron Enrichment Experiments, Proc. Natl. Acad. Sci., 101, 8537–8541, 2004. Wingenter, O W., Elliot, S M., and Blake, D R.: New directions: Enhancing the natural sulphur cycle to slow global warming, Atmos. Environ., 41, 7373–7375, 2007. Woodhouse, M T., Mann, G W., and Carslaw, K S.: New Directions: The impact of oceanic iron fertilization on cloud condensation nuclei, Atmos. Environ., 42, 5728–5730, 2008.