ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-11-15497-2011 A comprehensive numerical study of aerosol-cloud-precipitation interactions in marine stratocumulus Chen Y.-C. 1 Xue L. 2 Lebo Z. J. 1 Wang H. 3 Rasmussen R. M. 2 Seinfeld J. H. 1 4 Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California, USA National Center for Atmospheric Research (NCAR), Boulder, Colorado, USA Pacific Northwest National Laboratory (PNNL), Richland, Washington, USA Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA 20 05 2011 11 5 15497 15550 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/11/15497/2011/acpd-11-15497-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/11/15497/2011/acpd-11-15497-2011.pdf

Three-dimensional large-eddy simulations (LES) with detailed bin-resolved microphysics are performed to explore the diurnal variation of marine stratocumulus (MSc) clouds under clean and polluted conditions. The sensitivity of the aerosol-cloud-precipitation interactions to variation of sea surface temperature, free tropospheric humidity, large-scale divergence rate, and wind speed is assessed. The comprehensive set of simulations corroborates previous studies that (1) with moderate/heavy drizzle, an increase in aerosol leads to an increase in cloud thickness; and (2) with non/light drizzle, an increase in aerosol results in a thinner cloud, due to the pronounced effect on entrainment. It is shown that for higher SST, stronger large-scale divergence, drier free troposphere, or lower wind speed, the cloud thins and precipitation decreases. The sign and magnitude of the Twomey effect, droplet dispersion effect, cloud thickness effect, and overall cloud optical depth susceptibility to aerosol perturbations are evaluated by LES experiments and compared with analytical formulations. The Twomey effect emerges as dominant in total cloud susceptibility to aerosol perturbations. The dispersion effect, that of aerosol perturbations on the cloud droplet size spectrum, is positive (i.e., increase in aerosol leads to spectral narrowing) and accounts for 3 % to 10 % of the total cloud susceptibility at nighttime, with the largest influence in heavier drizzling clouds. The cloud thickness effect is negative (i.e., increase in aerosol leads to thinner cloud) for non/light drizzling cloud and positive for moderate/heavy drizzling clouds; the cloud thickness effect contributes 5 % to 22 % of the nighttime cloud susceptibility. The range of magnitude for each effect is more variable in the daytime owing to cloud thinning and decoupling. Overall, the cloud susceptibility is ~0.28 to 0.53 at night; an increase in aerosol concentration enhances cloud optical depth, especially with heavier precipitation and in a more pristine environment. The good agreement between LES experiments and analytical formulations suggests that the latter may be useful in evaluations of cloud susceptibility. The ratio of the magnitude of the cloud thickness effect to that of the Twomey effect depends on cloud base height and cloud thickness in unperturbed (clean) clouds.

 References Ackerman, A S., Toon, O B., Taylor, J P., Johnson, D W., Hobbs, P V., and Ferek, R J.: Effects of aerosols on cloud albedo: Evaluation of Twomey's parameterization of the cloud susceptibility using measurement of ship tracks, J. Atmos. Sci., 57, 2684–2695, 2000. Ackerman, A S., Kirkpatrick, M P., Stevens, D E., and Toon, O B.: The impact of humidity above stratiform clouds on indirect aerosol climate forcing, Nature, 432, 1014–1017, 2004. Ackerman, A S., vanZanten, M C., Stevens, B., Savic-Jovcic, V., Bretherton, C S., Chlond, A., Golaz, J.-C., Jiang, H., Khairoutdinov, M., Krueger, S K., Lewellen, D C., Lock, A., Moeng, C.-H., Nakamura, K., Petters, M D., Snider, J R., Weinbrecht, S., and Zulauf, M.: Large-eddy simulations of a drizzling, stratocumulus-topped marine boundary layer, Mon. Weather Rev., 137, 1083–1110, http://dx.doi.org/10.1175/2008MWR2582.1doi:10.1175/2008MWR2582.1, 2009. Albrecht, B.: Aerosols, Cloud Microphysics, and Fractional Cloudiness, Science, 245, 1227–1230, http://dx.doi.org/10.1126/science.245.4923.1227doi:10.1126/science.245.4923.1227, 1989. Brenguier, J.-L., Pawloska, H., Schüller, L., Preusker, R., and Fischer, J.: Radiative properties of boundary layer clouds: Droplet effective radius versus number concentration, J. Atmos. Sci., 57, 803–821, 2000. Bretherton, C S. and Wyant, M C.: Moisture transport, lower troposphere stability, and decoupling of cloud-topped boundary, J. Atmos. Sci., 54, 148–167, 1997. Bretherton, C S., Macvean, M K., Bechtold, P., Chlond, A., Cotton, W R., Cuxart, J., Cuijpers, H., Khairoutdinov, M., Kosovic, B., Lewellen, D., Moeng, C.-H., Siebesma, P., Stevens, B., Stevens, D E., Sykes, I., and Wyant, M C.: An intercomparison of radiatively driven entrainment and turbulence in a smoke cloud, as simulated by different numerical models, Q. J. Roy. Meteorol. Soc., 125, 391–423, 1999. Bretherton, C S., Blossey, P N., and Uchida, J.: Cloud droplet sedimentation, entrainment efficiency, and subtropical stratocumulus albedo, Geophys. Res. Lett., 34, L03813, http://dx.doi.org/10.1029/2006GL027648doi:10.1029/2006GL027648, 2007. Caldwell, P. and Bretherton, C S.: Response of a subtropical stratocumulus-capped mixed layer to climate and aerosol changes, J. Climate, 22, 20–38, 2009a. Caldwell, P. and Bretherton, C S.: Large eddy simulation of the diurnal cycle in Southeast Pacific stratocumulus, J. Atmos. Sci., 66, 432–449, 2009b. Chlond, A. and Wolkau, A.: Large-eddy simulation of a nocturnal stratocumulus-topped marine atmospheric boundary layer: An uncertainty analysis, Bound-Lay. Meteorol., 95, 31–55, 2000. Deardorff, J.: Stratocumulus-capped mixed layers derived from a three dimensional model, Bound-Lay. Meteorol., 18, 495–527, 1980. Duynkerke, P G., de~Roode, S R., van Zanten, M C., Calvo, J., Cuxart, J., Cheinet, S., Chlond, A., Grenier, H., Jonker, P J., Kohler, M., Lenderink, G., Lewellen, D., Lappen, C.-L., Lock, A P., Moeng, C.-H., Muller, F., Olmeda, D., Piriou, J.-M., Sanchez, E., and Sednev, I.: Observations and numerical simulations of the diurnal cycle of the EUROCS stratocumulus case, Q. J. Roy. Meteorol. Soc., 604, 3269–3296, 2004. Feingold, G. and Chuang, P Y.: Analysis of the influence of filmforming compounds on droplet growth: Implications for cloud microphysical processes and climate, J. Atmos. Sci., 59, 2006–2018, 2002. Feingold, G., Tzivion, S., and Levin, Z.: Evolution of raindrop spectra. Part I: solution to the stochastic collection/breakup equation using the method of moments, J. Atmos. Sci., 45, 3387–3399, 1988. Geresdi, I.: Idealized simulation of the Colorado hailstorm case: comparison of bulk and detailed microphysics, Atmos. Res., 45, 237–252, 1998. Hall, W D.: A detailed microphysical model within a two-dimensional framework: Model description and preliminary results, J. Atmos. Sci., 37, 2486–2507, 1980. Hill, A A., Dobbie, S., and Yin, Y.: The impact of aerosols on non-precipitating marine stratocumulus., Q. J. Roy. Meteorol. Soc., 134, 1143–1154, http://dx.doi.org/10.1002/qj.278doi:10.1002/qj.278, 2008. Hill, A A., Feingold, G., and Jiang, H.: The influence of entrainment and mixing assumption on aerosol-cloud interactions in marine stratocumulus, J. Atmos. Sci., 66, 1450–1464, 2009. IPCC: 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, edited by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K B., Tignor, M., and Miller, H L., Cambridge University Press, New York, NY, USA, 989 pp., 2007. Jiang, H., Feingold, G., and Cotton, W R.: Simulations of aerosol-clouddynamical feedbacks resulting from entrainment of aerosol into the marine boundary layer during the Atlantic Stratocumulus Transition Experiment, J. Geophys. Res., 107, 4813, http://dx.doi.org/10.1029/2001JD001502doi:10.1029/2001JD001502, 2002. Klein, S A. and Hartmann, D L.: The seasonal cycle of low stratiform clouds, J. Climate, 6, 1588–1606, 1993. Lilly, D K.: Models of cloud topped mixed layers under a strong inversion, Q. J. Roy. Meteorol. Soc., 94, 292–309, 1968. Lilly, D K.: Entrainment into mixed layers. Part II: A new closure, J. Atmos. Sci., 59, 3353–3361, 2002. Liu, Y G. and Daum, P H.: Anthropogenic aerosols: Indirect warming effect from dispersion forcing, Nature, 419, 580–581, 2002. Lu, M. and Seinfeld, J H.: Study of the aerosol indirect effect by large-eddy simulation of marine stratocumulus, J. Atmos. Sci., 62, 3909–3932, 2005. Lu, M. and Seinfeld, J H.: Effect of aerosol number concentration on cloud droplet dispersion: A large-eddy simulation study and implications for aerosol indirect forcing, J. Geophys. Res., 111 D02207, http://dx.doi.org/10.1029/2005JD006419doi:10.1029/2005JD006419, 2006. Lu, M.-L., Conant, W C., Jonsson, H H., Varutbangkul, V., Flagan, R C., and Seinfeld, J H.: The Marine Stratus/Stratocumulus Experiment (MASE): Aerosol-cloud relationships in marine stratocumulus, J. Geophys. Res., 112, D10209, http://dx.doi.org/10.1029/2006JD007985doi:10.1029/2006JD007985, 2007. Martin, G M., Johnson, D W., and Spice, A.: The measurement and parameterization of effective radius of droplets in warm stratocumulus clouds, J. Atmos. Sci., 51, 1823–1842, 1994. Miles, N L., Verlinde, J., and Clothiaux, E E.: Cloud droplet size distributions in low-level stratiform clouds, J. Atmos. Sci., 57, 295–311, 2000. Mlawer, E J., Taubman, S J., Brown, P D., Iacono, M J., and Clough, S A.: Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated-k model for the longwave, J. Geophys. Res., 102, 16663–16682, 1997. Moeng, C.-H., Dudhia, J., Klemp, J B., and Sullivan, P P.: Examining two-way grid nesting for large eddy simulation of the PBL using the WRF model, Mon. Weather Rev., 135, 2295–2311, http://dx.doi.org/10.1175/MWR3406.1doi:10.1175/MWR3406.1, 2007. Petters, M D. and Kreidenweis, S M.: A single parameter representation of hygroscopic growth and cloud condensation nucleus activity, Atmos. Chem. Phys., 7, 1961–1971, http://dx.doi.org/10.5194/acp-7-1961-2007doi:10.5194/acp-7-1961-2007, 2007. Pincus, R. and Baker, M B.: Effect of precipitation on the albedo susceptibility of marine boundary layer clouds, Nature, 372, 250–252, 1994. Pruppacher, H R. and Klett, J D.: Microphysics of Clouds and Precipitation, Kluwer Academic Publishers, Boston, USA, 954 pp., 1997. Randall, D A., Coakley~Jr., J A., Fairall, C W., Kropfli, R A., and Lenschow, D H.: Outlook for research on subtropical marine stratiform clouds, B. Am. Meteorol. Soc., 65, 1290–1301, 1984. Rasmussen, R M., Geresdi, I., Thompson, G., Manning, K., and Karplus, E.: Freezing drizzle formation in stably stratified layer clouds: The role of radiative cooling of cloud droplets, cloud condensation nuclei, and ice initiation, J. Atmos. Sci., 59, 837–860, 2002. Reisin, T., Levin, Z., and Tzivion, S.: Rain production in convective clouds as simulated in an axisymmetric model with detailed microphysics. Part I: description of the model, J. Atmos. Sci., 53, 497–519, 1996. Rotstayn, L D. and Liu, Y.: Sensitivity of the first indirect aerosol effect to an increase of cloud droplet spectral dispersion with droplet number concentration, J. Climate, 16, 3476–3481, 2003. Rotstayn, L D. and Liu, Y.: Cloud droplet spectral dispersion and the indirect aerosol effect: Comparison of two treatments in a GCM, Geophys. Res. Lett., 36, L10801, http://dx.doi.org/10.1029/2009GL038216doi:10.1029/2009GL038216, 2009. Sandu, I., Brenguier, J., Geoffroy, O., Thouron, O., and Masson, V.: Aerosol impacts on the diurnal cycle of marine stratocumulus, J. Atmos. Sci., 65, 2705–2718, 2008. Sandu, I., Brenguier, J., Thouron, O., and Stevens, B.: How important is the vertical structure for the representation of aerosol impacts on the diurnal cycle of marine stratocumulus?, Atmos. Chem. Phys., 9, 4039–4052, http://dx.doi.org/10.5194/acp-9-4039-2009doi:10.5194/acp-9-4039-2009, 2009. Savic-Jovcic, V. and Stevens, B.: The structure and mesoscale organization of precipitating stratocumulus, J. Atmos. Sci., 65, 1587–1605, 2008. Seinfeld, J H. and Pandis, S N.: Atmospheric Chemistry and Physics, John Wiley and Sons, Inc., Hoboken, NJ, USA, 2 edn., 2006. Shao, H. and Liu, G.: A critical examination of the observed first aerosol indirect effect, J. Atmos. Sci., 66, 1018–1032, 2009. Stevens, B.: Atmospheric moist convection, Annu. Rev. Earth Pl. Sc., 33, 605–643, http://dx.doi.org/10.1146/annurev.earth.33.092203.122658doi:10.1146/annurev.earth.33.092203.122658, 2005. Stevens, B.: Bulk boundary-layer concepts for simplified models of tropical dynamics, Theor. Comp. Fluid Dyn., 20, 279–304, http://dx.doi.org/10.1007/s00162-006-0032-zdoi:10.1007/s00162-006-0032-z, 2006. Stevens, B. and Brenguier, J.-L.: Cloud controlling factors: low clouds, in: Clouds in the perturbed climate system: their relationship to energy balance, atmospheric dynamics, and precipitation, edited by: Heintzenberg, J. and Charlson, R J., 173–196, MIT Press, 2009. Stevens, B. and Feingold, G.: Untangling aerosol effects on clouds and precipitation in a buffered system, Nature, 461, 607–613, http://dx.doi.org/10.1038/nature08281doi:10.1038/nature08281, 2009. Stevens, B., Cotton, W R., Feingold, G., and Moeng, C.-H.: Large-eddy simulations of strongly precipitating, shallow, stratocumulus-topped boundary layers, J. Atmos. Sci., 55, 3616–3638, 1998. Stevens, B., Lenschow, D H., Faloona, I., Moeng, C.-H., Lilly, D K., Blomquist, B., Vali, G., Bandy, A., Campos, T., Gerber, H., Haimov, S., Morley, B., and Thornton, D.: On entrainment rates in nocturnal marine stratocumulus, Q. J. Roy. Meteorol. Soc., 129, 3469–3493, http://dx.doi.org/10.1256/qj.02.202doi:10.1256/qj.02.202, 2003. Stevens, B., Moeng, C.-H., Ackerman, A S., Bretherton, C S., Chlond, A., De~Roode, S., Edwards, J., Golaz, J., Jiang, H., Khairoutdinov, M., Kirkpatrick, M P., Lewellen, D C., Lock, A., Muller, F., Stevens, D E., Whelan, E., and Zhu, P.: Evaluation of large-eddy simulations via observations of nocturnal marine stratocumulus, Mon. Weather Rev., 133, 1443–1462, 2005. Stevens, D E. and Bretherton, C S.: Effects of resolution on the simulation of stratocumulus entrainment, Q. J. Roy. Meteorol. Soc., 125, 425–439, 1999. Turton, J. and Nicholls, S.: A study of the diurnal variation of stratocumulus using a multiple mixed-layer model, Q. J. Roy. Meteorol. Soc., 113, 969–1011, 1987. Twomey, S.: The nuclei of natural cloud formation Part 2: The supersaturation in natural clouds and the variation of cloud droplet concentration, Pure Appl. Geophys., 43, 243–249, 1959. Twomey, S.: The influence of pollution on the shortwave albedo of clouds, J. Atmos. Sci., 34, 1149–1152, 1977. Tzivion, S., Feingold, G., and Levin, Z.: An efficient numerical solution to the stochastic collection equation, J. Atmos. Sci., 44, 3139–3149, 1987. Tzivion, S., Feingold, G., and Levin, Z.: The evolution of raindrop spectra. Part II: collisional collection/breakup and evaporation in a rainshaft, J. Atmos. Sci., 46, 3312–3327, 1989. Uchida, J., Bretherton, C S., and Blossey, P N.: The sensitivity of stratocumulus-capped mixed layers to cloud droplet concentration: do LES and mixed-layer models agree?, Atmos. Chem. Phys., 10, 4097–4109, http://dx.doi.org/10.5194/acp-10-4097-2010doi:10.5194/acp-10-4097-2010, 2010. Wang, H. and Feingold, G.: Modeling mesoscale cellular structures and drizzle in marine stratocumulus. Part I: Impact of drizzle on the formation and evolution of open cells, J. Atmos. Sci., 66, 3237–3256, 2009a. Wang, H. and Feingold, G.: Modeling mesoscale cellular structures and drizzle in marine stratocumulus. Part II: The microphysics and dynamics of the boundary region between open and closed cells, J. Atmos. Sci., 66, 3257–3275, 2009b. Wang, H., Skamarock, W C., and Feingold, G.: Evaluation of scalar advection schemes in the advanced research WRF model using large-eddy simulations of aerosol-cloud interactions, Mon. Weather Rev., 137, 2547–2558, http://dx.doi.org/10.1175/2009MWR2820.1doi:10.1175/2009MWR2820.1, 2009. Wang, H., Feingold, G., Wood, R., and Kazil, J.: Modeling microphysical and meteorological controls on precipitation and cloud cellular structures in Southeast Pacific stratocumulus, Atmos. Chem. Phys., 10, 6347–6362, http://dx.doi.org/10.5194/acp-10-6347-2010doi:10.5194/acp-10-6347-2010, 2010. Wang, S., Wang, Q., and Feingold, G.: Turbulence, condensation, and liquid water transport in numerically simulated nonprecipitating stratocumulus clouds, J. Atmos. Sci., 60, 262–278, 2003. Warren, S G., Hahn, C J., London, J., Chervine, R M., and Jenne, R L.: Global distribution of total cloud cover and cloud type amounts over the ocean, NCAR/TN-317 STR, NCAR Tech. Note., 41 pp., 1988. Wood, R.: Cancellation of aerosol indirect effects in marine stratocumulus through cloud thinning, J. Atmos. Sci., 64, 2657–2669, http://dx.doi.org/10.1175/JAS3942.1doi:10.1175/JAS3942.1, 2007. Wood, R., Irons, S., and Jonas, P R.: How important is the spectral ripening effect in stratiform boundary layer clouds? Studies using simple trajectory analysis, J. Atmos. Sci., 59, 2681–2693, 2002. Xue, H. and Feingold, G.: Large-eddy simulations of trade wind cumuli: Investigation of aerosol indirect effects, J. Atmos. Sci., 63, 1605–1622, 2006. Xue, L., Teller, A., Rasmussen, R M., Geresdi, I., and Pan, Z.: Effects of aerosol solubility and regeneration on warm-phase orographic clouds and precipitation simulated by a detailed bin microphysical scheme, J. Atmos. Sci., 67, 3336–3354, http://dx.doi.org/10.1175/2010JAS3511.1doi:10.1175/2010JAS3511.1, 2010. Yamaguchi, T. and Randall, D A.: Large-eddy simulation of evaporatively driven entrainment in cloud-topped mixed layers, J. Atmos. Sci., 65, 1481–1504, 2008.