• Bellon, G., , and B. Stevens, 2012: Using the sensitivity of large simulations to evaluate atmospheric boundary layer models. J. Atmos. Sci., 69, 15821601.

    • Search Google Scholar
    • Export Citation
  • Betts, A. K., 1982: Saturation point analysis of moist convective overturning. J. Atmos. Sci., 39, 14841505.

  • Betts, A. K., , and Harshvardhan, 1987: Thermodynamic constraint on the cloud liquid water feedback in climate models. J. Geophys. Res., 92 (D7), 84838485.

    • Search Google Scholar
    • Export Citation
  • Bony, S., , and J. L. Dufresne, 2006: Marine boundary layer clouds at the heart of tropical cloud feedback uncertainties in climate models. Geophys. Res. Lett., 32, L20806, doi:10.1029/2005GL023851.

    • Search Google Scholar
    • Export Citation
  • Brenguier, J.-L., , H. Pawlowska, , L. Schüller, , R. Preusker, , J. Fischer, , and Y. Fouquart, 2000: Radiative properties of boundary layer clouds: Droplet effective radius versus number concentration. J. Atmos. Sci., 57, 803821.

    • Search Google Scholar
    • Export Citation
  • Bretherton, C. S., , and M. C. Wyant, 1997: Moisture transport, lower tropospheric stability, and decoupling of cloud-topped boundary layers. J. Atmos. Sci., 54, 148167.

    • Search Google Scholar
    • Export Citation
  • Charlock, T. P., 1982: Cloud optical feedback and climate stability in a radiative-convective model. Tellus, 34, 245254.

  • Del Genio, A. D., , and A. B. Wolf, 2000: The temperature dependence of the liquid water path of low clouds in the southern Great Plains. J. Climate, 13, 34653486.

    • Search Google Scholar
    • Export Citation
  • Fairall, C. W., , E. F. Bradley, , J. E. Hare, , A. A. Grachev, , and J. B. Edson, 2003: Bulk parameterization of air–sea fluxes: Updates and verification for the COARE algorithm. J. Climate, 16, 571591.

    • Search Google Scholar
    • Export Citation
  • Forster, P., and Coauthors, 2007: Changes in atmospheric constituents and in radiative forcing. Climate Change 2007: The Physical Science Basis, S. Solomon et al., Eds., Cambridge University Press, 129–234.

  • Hartmann, D. L., , and D. A. Short, 1980: On the use of Earth radiation budget statistics for studies of clouds and climate. J. Atmos. Sci., 37, 12331250.

    • Search Google Scholar
    • Export Citation
  • Held, I. M., , and B. J. Soden, 2000: Water vapor feedback and global warming. Annu. Rev. Energy Environ., 25, 441475.

  • Lilly, D. K., 1967: The representation of small-scale turbulence in numerical simulation experiments. Proc. IBM Scientific Computing Symp. on Environmental Sciences, Yorktown Heights, NY, IBM, 195–210.

  • Matheou, G., , D. Chung, , L. Nuijens, , B. Stevens, , and J. Teixeira, 2011: On the fidelity of large-eddy simulation of shallow precipitating cumulus convection. Mon. Wea. Rev., 139, 29182939.

    • Search Google Scholar
    • Export Citation
  • Möller, F., 1963: On the influence of changes in the CO2 concentration in air on the radiation balance of the Earth’s surface and on the climate. J. Geophys. Res., 68, 38773886.

    • Search Google Scholar
    • Export Citation
  • Nuijens, L., , and B. Stevens, 2012: The influence of wind speed on shallow marine cumulus convection. J. Atmos. Sci., 69, 168184.

  • Nuijens, L., , B. Stevens, , and A. P. Siebesma, 2009: The environment of precipitating shallow cumulus convection. J. Atmos. Sci., 66, 19621979.

    • Search Google Scholar
    • Export Citation
  • Paltridge, G. W., 1980: Cloud-radiation feedback to climate. Quart. J. Roy. Meteor. Soc., 106, 895899.

  • Plass, G. N., 1956: The carbon dioxide theory of climatic change. Tellus, 8, 140154.

  • Rauber, R. M., and Coauthors, 2007: Rain in shallow cumulus over the ocean—The RICO campaign. Bull. Amer. Meteor. Soc., 88, 19121928.

    • Search Google Scholar
    • Export Citation
  • Richter, I., , and S.-P. Xie, 2008: Muted precipitation increase in global warming simulations: A surface evaporation perspective. J. Geophys. Res., 113, D24118, doi:10.1029/2008JD010561.

    • Search Google Scholar
    • Export Citation
  • Rieck, M., 2011: Testing the liquid water lapse rate feedback in shallow convection using large eddy simulations. M.S. thesis, University of Hamburg, 65 pp.

  • Savic-Jovcic, V., , and B. Stevens, 2008: The structure and mesoscale organization of precipitating stratocumulus. J. Atmos. Sci., 65, 15871605.

    • Search Google Scholar
    • Export Citation
  • Schneider, S. H., 1972: Cloudiness as a global climatic feedback mechanism: The effects on the radiation balance and surface temperature of variations in cloudiness. J. Atmos. Sci., 29, 14131422.

    • Search Google Scholar
    • Export Citation
  • Siebesma, A. P., and Coauthors, 2003: A large eddy simulation intercomparison study of shallow cumulus convection. J. Atmos. Sci., 60, 12011219.

    • Search Google Scholar
    • Export Citation
  • Somerville, R. C. J., , and L. A. Remer, 1984: Cloud optical thickness feedbacks in the CO2 climate problem. J. Geophys. Res., 89 (D6), 96689672.

    • Search Google Scholar
    • Export Citation
  • Stephens, G. L., 1978: Radiation profiles in extended water clouds. I: Theory. J. Atmos. Sci., 35, 21112122.

  • Stephens, G. L., , and Y. Hu, 2010: Are climate-related changes to the character of global-mean precipitation predictable? Environ. Res. Lett., 5, 025209, doi:10.1088/1748-9326/5/2/025209.

    • Search Google Scholar
    • Export Citation
  • Stevens, B., 2007: On the growth of layers of nonprecipitating cumulus convection. J. Atmos. Sci., 64, 29162931.

  • Stevens, B., , and A. Seifert, 2008: Understanding macrophysical outcomes of microphysical choices in simulations of shallow cumulus convection. J. Meteor. Soc. Japan, 86A, 143162.

    • Search Google Scholar
    • Export Citation
  • Stevens, B., , and G. Feingold, 2009: Untangling aerosol effects on clouds and precipitation in a buffered system. Nature, 461, 607613.

    • Search Google Scholar
    • Export Citation
  • Stevens, B., , and S. E. Schwartz, 2012: Observing and modeling Earth’s energy flows. Surv. Geophys., in press.

  • Stevens, B., and Coauthors, 2001: Simulations of trade wind cumuli under a strong inversion. J. Atmos. Sci., 58, 18701891.

  • Tselioudis, G., , W. B. Rossow, , and D. Rind, 1992: Global patterns of cloud optical thickness variation with temperature. J. Climate, 5, 14841495.

    • Search Google Scholar
    • Export Citation
  • Twomey, S., 1971: The influence of atmospheric particulates on cloud and planetary albedo. Bull. Amer. Meteor. Soc., 52, 265266.

  • vanZanten, M. C., , B. Stevens, , and L. Nuijens, 2011: Controls on precipitation and cloudiness in simulations of trade-wind cumulus as observed during RICO. J. Adv. Model. Earth Syst., 3, M06001, doi:10.1029/2011MS000056.

    • Search Google Scholar
    • Export Citation
  • Xu, K.-M., , A. Cheng, , and M. Zhang, 2010: Cloud-resolving simulation of low-cloud feedback to an increase in sea surface temperature. J. Atmos. Sci., 67, 730748.

    • Search Google Scholar
    • Export Citation
  • Zhang, M., , and C. S. Bretherton, 2008: Mechanisms of low cloud–climate feedback in idealized single-column simulations with the Community Atmospheric Model, version 3 (CAM3). J. Climate, 21, 48594878.

    • Search Google Scholar
    • Export Citation
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Marine Boundary Layer Cloud Feedbacks in a Constant Relative Humidity Atmosphere

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  • 1 Max Planck Institute for Meteorology, Hamburg, Germany
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Abstract

The mechanisms that govern the response of shallow cumulus, such as found in the trade wind regions, to a warming of the atmosphere in which large-scale atmospheric processes act to keep relative humidity constant are explored. Two robust effects are identified. First, and as is well known, the liquid water lapse rate increases with temperature and tends to increase the amount of water in clouds, making clouds more reflective of solar radiation. Second, and less well appreciated, the surface fluxes increase with the saturation specific humidity, which itself is a strong function of temperature. Using large-eddy simulations it is shown that the liquid water lapse rate acts as a negative feedback: a positive temperature increase driven by radiative forcing is reduced by the increase in cloud water and hence cloud albedo. However, this effect is more than compensated by a reduction of cloudiness associated with the deepening and relative drying of the boundary layer, driven by larger surface moisture fluxes. Because they are so robust, these effects are thought to underlie changes in the structure of the marine boundary layer as a result of global warming.

Corresponding author address: Bjorn Stevens, Max-Planck-Institut für Meteorologie, Hamburg, Germany. E-mail: bjorn.stevens@zmaw.de

Abstract

The mechanisms that govern the response of shallow cumulus, such as found in the trade wind regions, to a warming of the atmosphere in which large-scale atmospheric processes act to keep relative humidity constant are explored. Two robust effects are identified. First, and as is well known, the liquid water lapse rate increases with temperature and tends to increase the amount of water in clouds, making clouds more reflective of solar radiation. Second, and less well appreciated, the surface fluxes increase with the saturation specific humidity, which itself is a strong function of temperature. Using large-eddy simulations it is shown that the liquid water lapse rate acts as a negative feedback: a positive temperature increase driven by radiative forcing is reduced by the increase in cloud water and hence cloud albedo. However, this effect is more than compensated by a reduction of cloudiness associated with the deepening and relative drying of the boundary layer, driven by larger surface moisture fluxes. Because they are so robust, these effects are thought to underlie changes in the structure of the marine boundary layer as a result of global warming.

Corresponding author address: Bjorn Stevens, Max-Planck-Institut für Meteorologie, Hamburg, Germany. E-mail: bjorn.stevens@zmaw.de
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