Skip to main content
SpringerLink
Log in

A study of shallow cumulus cloud droplet dispersion by large eddy simulations

  • Published:
Acta Meteorologica Sinica Aims and scope Submit manuscript

Abstract

Cloud droplet dispersion is an important parameter in estimating aerosol indirect effect on climate in general circulation models (GCMs). This study investigates droplet dispersion in shallow cumulus clouds under different aerosol conditions using three-dimensional large eddy simulations (LES). It is found that cloud droplet mean radius, standard deviation, and relative dispersion generally decrease as aerosol mixing ratio increases from 25 mg−1 (clean case) to 100 mg−1 (moderate case), and to 2000 mg−1 (polluted case). Under all the three simulated aerosol conditions, cloud droplet mean radius and standard deviation increase with height. However, droplet relative dispersion increases with height only in the polluted case, and does not vary with height in the clean and moderate cases.

The mechanisms for cloud droplet dispersion are also investigated. An additional simulation without considering droplet collision-coalescence and sedimentation under the aerosol mixing ratio of 25 mg−1 shows smaller values of droplet mean radius, standard deviation, and relative dispersion as compared to the base clean case. This indicates that droplet collision-coalescence plays an important role in broadening droplet spectra. Results also suggest that the impact of homogeneous mixing on cumulus cloud droplet spectra is significant under all the three simulated aerosol conditions. In weak mixing (strong updraft) regions where clouds are closer to be adiabatic, cloud droplets tend to have larger mean radius, smaller standard deviation, and hence smaller relative dispersion than those in stronger mixing (downdraft or weak updraft) regions.

The parameterized cloud optical depth in terms of cloud liquid water content, droplet number concentration, and relative dispersion is only slightly smaller than the result calculated from detailed droplet spectra, indicating that current parameterization of cloud optical depth as used in many GCMs is plausible for low clouds.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • Albrecht, B. A., 1989: Aerosols, cloud microphysics, and fractional cloudiness. Science, 245(4923), 1227–1230.

    Article  Google Scholar 

  • Arabas, S., H. Pawlowska, and W. W. Grabowski, 2009: Effective radius and droplet spectral width from in-situ aircraft observations in trade-wind cumuli during RICO. Geophys. Res. Lett., 36, doi: 10.1029/2009gl038257.

  • Deng, Z. Z., C. S. Zhao, Q. Zhang, M. Y. Huang, and X. C. Ma, 2009: Statistical analysis of microphysical properties and the parameterization of effective radius of warm clouds in Beijing area. Atmos. Res., 93(4), 888–896.

    Article  Google Scholar 

  • Intergovernmental Panel on Climate Change, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. New York, Cambridge Unversity Press, 136 pp.

    Google Scholar 

  • Liu, Y. G., and P. H. Daum, 2000: Spectral dispersion of cloud droplet size distributions and the parameterization of cloud droplet effective radius. Geophys. Res. Lett., 27(13), 1903–1906.

    Article  Google Scholar 

  • —, and —, 2002: Anthropogenic aerosols-indirect warming effect from dispersion forcing. Nature, 419(6907), 580–581.

    Article  Google Scholar 

  • —, —, and S. S. Yum, 2006: Analytical expression for the relative dispersion of the cloud droplet size distribution. Geophys. Res. Lett., 33(2), doi: 10.1029/2005gl024052.

  • Liu, Y. G., P. H. Daum, H. Guo, and Y. R. Peng, 2008: Dispersion bias, dispersion effect, and the aerosolcloud conundrum. Environ. Res. Lett., 3(4), doi: 10.1088/1748-9326/3/4/045021.

  • Lu, M. L., and J. H. Seinfeld, 2006: Effect of aerosol number concentration on cloud droplet dispersion: A large-eddy simulation study and implications for aerosol indirect forcing. J. Geophys. Res. -Atmos., 111(D2), doi: 10.1029/2005jd006419.

  • —, W. C. Conant, H. H. Jonsson, V. Varutbangkul, R. C. Flagan, and J. H. Seinfeld, 2007: The Marine Stratus/Stratocumulus Experiment (MASE): Aerosol-cloud relationships in marine stratocumulus. J. Geophys. Res. -Atmos., 112(D10), doi: 10.1029/2006jd007985.

  • —, G. Feingold, H. H. Jonsson, P. Y. Chuang, H. Gates, R. C. Flagan, and J. H. Seinfeld, 2008: Aerosolcloud relationships in continental shallow cumulus. J. Geophys. Res. -Atmos., 113(D15), doi: 10.1029/2007jd009354.

  • Martins, J. A., and M. A. F. S. Dias, 2009: The impact of smoke from forest fires on the spectral dispersion of cloud droplet size distributions in the Amazonian region. Environ. Res. Lett., 4(1), doi: 10.1088/1748-9326/4/1/015002.

  • Miles, N. L., J. Verlinde, and E. E. Clothiaux, 2000: Cloud droplet size distributions in low-level stratiform clouds. J. Atmos. Sci., 57(2), 295–311.

    Article  Google Scholar 

  • Pawlowska, H., W. W. Grabowski, and J. L. Brenguier, 2006: Observations of the width of cloud droplet spectra in stratocumulus. Geophys. Res. Lett., 33(19), doi: 10.1029/2006gl026841.

  • Peng, Y. R., and U. Lohmann, 2003: Sensitivity study of the spectral dispersion of the cloud droplet size distribution on the indirect aerosol effect. Geophys. Res. Lett., 30(10), doi: 10.1029/2003gl017192.

  • —, U. Lohmann, R. Leaitch, and M. Kulmala, 2007: An investigation into the aerosol dispersion effect through the activation process in marine stratus clouds. J. Geophys. Res. -Atmos., 112(D11), doi: 10.1029/2006jd007401.

  • Rotstayn, L. D., and Y. G. Liu, 2003: Sensitivity of the first indirect aerosol effect to an increase of cloud droplet spectral dispersion with droplet number concentration, J. Climate. 16(21), 3476–3481.

    Article  Google Scholar 

  • Shaw, R. A., W. C. Reade, L. R. Collins, J. Verlinde, 1998: Preferential concentration of cloud droplets by turbulence: Effects on the early evolution of cumulus cloud droplet spectra. J. Atmos. Sci., 55(11), 1965–1976.

    Article  Google Scholar 

  • Siebesma, A. P., et al., 2003: A large eddy simulation intercomparison study of shallow cumulus convection. J. Atmos. Sci., 60(10), 1201–1219.

    Article  Google Scholar 

  • Twomey, S., 1974: Pollution and planetary albedo. Atmos. Environ., 8(12), 1251–1256.

    Article  Google Scholar 

  • —, 1977: Influence of pollution on shortwave albedo of clouds. J. Atmos. Sci., 34(7), 1149–1152.

    Article  Google Scholar 

  • Wang, J., P. H. Daum, S. S. Yum, Y. A. Liu, G. I. Senum, M. L. Lu, J. H. Seinfeld, and H. Jonsson, 2009: Observations of marine stratocumulus microphysics and implications for processes controlling droplet spectra: Results from the Marine Stratus/Stratocumulus Experiment. J. Geophys. Res. -Atmos., 114, doi: 10.1029/2008jd011035.

  • Warner, J., 1969: Microstructure of cumulus cloud. Part I: General features of droplet spectrum. J. Atmos. Sci., 26(5), 1049–1059.

    Article  Google Scholar 

  • Xue, H. W., and G. Feingold, 2004: A modeling study of the effect of nitric acid on cloud properties. J. Geophys. Res. -Atmos., 109(D18), doi: 10.1029/2004jd004750.

  • —, and —, 2006: Large-eddy simulations of trade wind cumuli: Investigation of aerosol indirect effects. J. Atmos. Sci., 63(6), 1605–1622.

    Article  Google Scholar 

  • Yum, S. S., and J. G. Hudson, 2005: Adiabatic predictions and observations of cloud droplet spectral broadness. Atmos. Res., 73(3–4), 203–223.

    Article  Google Scholar 

  • Zhao, C. S., et al., 2006: Aircraft measurements of cloud droplet spectral dispersion and implications for indirect aerosol radiative forcing. Geophys. Res. Lett., 33(16), doi: 10.1029/2006gl026653.

Download references

Author information

Authors and Affiliations

  1. Department of Atmospheric Sciences, School of Physics, Peking University, Beijing, 100871, China

    Xiaofeng Wang  (王晓峰) & Huiwen Xue  (薛惠文)

  2. Chinese Academy of Meteorological Sciences, Beijing, 100081, China

    Wen Fang  (房 文)

  3. China Meteorological Administration, Beijing, 100081, China

    Guoguang Zheng  (郑国光)

Authors
  1. Xiaofeng Wang  (王晓峰)
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Huiwen Xue  (薛惠文)
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Wen Fang  (房 文)
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Guoguang Zheng  (郑国光)
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Huiwen Xue  (薛惠文).

Additional information

Supported by the 11th Five-Year National Key Technology R&D Program of China under Grant No. 2006BAC12B003 and National Natural Science Foundation of China under Grant No. 40675004.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Wang, X., Xue, H., Fang, W. et al. A study of shallow cumulus cloud droplet dispersion by large eddy simulations. Acta Meteorol Sin 25, 166–175 (2011). https://doi.org/10.1007/s13351-011-0024-9

Download citation

  • Received:

  • Revised:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s13351-011-0024-9

Key words

Search

Navigation