Editorial Type:
Article
Article Type:
Research Article

Large Eddy Simulation of Shallow Cumulus Convection during BOMEX: Sensitivity to Microphysics and Radiation

Hongli Jiang Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado

Search for other papers by Hongli Jiang in
Current site
Google Scholar
PubMed Close
and
William R. Cotton Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado

Search for other papers by William R. Cotton in
Current site
Google Scholar
PubMed Close
Print Publication:
01 Feb 2000
DOI:
https://doi.org/10.1175/1520-0469(2000)057<0582:LESOSC>2.0.CO;2
Page(s):
582–594
Restricted access

Abstract

A number of large eddy simulations with the Regional Atmospheric Modeling System have been made to study the sensitivity of shallow marine cumulus convection to different microphysics and radiation schemes. In particular, the sensitivity of shallow marine cumulus convection to drizzle and radiation effects, and how drizzle and radiation modify turbulent fluxes, are investigated.

It is shown that for the case of prescribed radiative heating, drizzle—albeit very slight—leads to reduced buoyancy fluxes and less turbulence. Consequently, drizzling boundary layers appear to entrain less than their nondrizzling counterpart. Heavy drizzle events are simulated in association with deeper clouds as high as 2 km, even though the majority of clouds are only a few hundred meters deep. A heavier and longer lasting drizzle episode associated with a deeper boundary layer is produced when a two-stream radiative parameterization replaces the prescribed radiative heating in the simulation. Simulated surface precipitation rates agree reasonably well with observations. The greatest alteration in boundary layer structure is obtained when radiative heating interacts explicitly with the broadened drop distribution associated with drizzle formation.

Corresponding author address: Hongli Jiang, Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80523-1371.

Abstract

A number of large eddy simulations with the Regional Atmospheric Modeling System have been made to study the sensitivity of shallow marine cumulus convection to different microphysics and radiation schemes. In particular, the sensitivity of shallow marine cumulus convection to drizzle and radiation effects, and how drizzle and radiation modify turbulent fluxes, are investigated.

It is shown that for the case of prescribed radiative heating, drizzle—albeit very slight—leads to reduced buoyancy fluxes and less turbulence. Consequently, drizzling boundary layers appear to entrain less than their nondrizzling counterpart. Heavy drizzle events are simulated in association with deeper clouds as high as 2 km, even though the majority of clouds are only a few hundred meters deep. A heavier and longer lasting drizzle episode associated with a deeper boundary layer is produced when a two-stream radiative parameterization replaces the prescribed radiative heating in the simulation. Simulated surface precipitation rates agree reasonably well with observations. The greatest alteration in boundary layer structure is obtained when radiative heating interacts explicitly with the broadened drop distribution associated with drizzle formation.

Corresponding author address: Hongli Jiang, Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80523-1371.

Save
Cover Journal of the Atmospheric Sciences
Journal of the Atmospheric Sciences

  • Browning, K. A., Ed., 1994: GEWEX Cloud System Study (GCSS) Science Plan. IGPO Publication Series, Vol. 11, World Climate Research Programme International GEWEX Project Office, 84 pp.

  • Davidson, B., 1968: The Barbados Oceanographic and Meteorological Experiment. Bull. Amer. Meteor. Soc.,49, 928–934.

  • Dharssi, I., R. Kershaw, and W. K. Tao, 1997: Sensitivity of a simulated tropical squall line to long-wave radiation. Quart. J. Roy. Meteor. Soc.,123, 187–206.

  • Feingold, G., R. L. Walko, B. Stevens, and W. R. Cotton, 1998: Simulations of marine stratocumulus using a new microphysical parameterization scheme. Atmos. Res.,47–48, 505–528.

  • Harrington, J. Y., T. Reisin, W. R. Cotton, and S. M. Kreidenweis, 1999: Cloud resolving simulations of Arctic stratus. Part II: Transition-season clouds. Atmos. Res.,51, 45–75.

  • Holland, J. Z., and E. M. Rasmusson, 1973: Measurement of the atmospheric mass, energy, and momentum budgets over a 500-kilometer square of tropical ocean. Mon. Wea. Rev.,101, 44–55.

  • Mason, B. J., 1971: The Physics of Clouds. Oxford University Press, 671 pp.

  • Meyers, M. P., R. L. Walko, J. Y. Harrington, and W. R. Cotton, 1997:New RAMS cloud microphysics parameterization. Part II: The two-moment scheme. Atmos. Res.,45, 3–39.

  • Mitchell, D. L., A. Macke, and Y. Liu, 1996: Modeling cirrus clouds. Part II: Treatment of radiative properties. J. Atmos. Sci.,53, 2967–2988.

  • Moeng, C.-H., and Coauthors, 1996: Simulation of a stratocumulus-topped planetary boundary layer: Intercomparison among different numerical codes. Bull. Amer. Meteor. Soc.,77, 261–278.

  • Nicholls, S., and M. A. LeMone, 1980: The fair weather boundary layer in GATE: The relationship of subcloud fluxes and structure to the distribution and enhancement of cumulus clouds. J. Atmos. Sci.,37, 2051–2067.

  • ——, and ——, 1982: The simulation of a fair weather marine boundary in GATE using a three-dimensional model. Quart. J. Roy. Meteor. Soc.,108, 167–190.

  • Nitta, T., and S. Esbensen, 1974: Heat and moisture budget analyses using BOMEX data. Mon. Wea. Rev.,102, 17–28.

  • Pennel, W. T., and M. A. LeMone, 1974: An experimental study of turbulent structure in the fair-weather trade wind boundary layer. J. Atmos. Sci.,31, 1308–1323.

  • Pielke, R. A., and Coauthors, 1992: A comprehensive meteorological modeling system—RAMS. Meteor. Atmos. Phys.,49, 69–91.

  • Ritter, B., and J. F. Geleyn, 1992: A comprehensive radiation scheme for numerical weather prediction models with potential application in climate simulations. Mon. Wea. Rev.,120, 303–325.

  • Siebesma, A. P., and J. W. M. Cuijpers, 1995: Evaluation of parametric assumptions for shallow cumulus convection. J. Atmos. Sci.,52, 650–666.

  • Slingo, A., and H. M. Schrecker, 1982: On the shortwave radiative properties of stratiform water clouds. Quart. J. Roy. Meteor. Soc.,108, 407–426.

  • Soong, S.-T., and Y. Ogura, 1980: Response of tradewind cumuli to large-scale processes. J. Atmos. Sci.,37, 2035–2050.

  • Stevens, B., 1996: On the dynamics of precipitating stratocumulus. Ph.D. dissertation, Colorado State University, 140 pp. [Available from Dept. of Atmospheric Sciences, Colorado State University, Fort Collins, CO 80523.].

  • ——, W. R. Cotton, G. Feingold, and C.-H. Moeng, 1998: Large-eddy simulations of strongly precipitating, shallow, stratocumulus-topped boundary layers. J. Atmos. Sci.,55, 3616–3638.

  • Stull, R. B., 1988: An Introduction to Boundary Layer Meteorology. Kluwer Academic, 666 pp.

  • Tao, W., J. Simpson, C. Sui, B. Ferrier, S. Land, J. Scala, M. Chou, and K. Pickering, 1993: Heating, moisture, and water budgets of tropical and midlatitude squall lines: Comparisons and sensitivity to longwave radiation. J. Atmos. Sci.,50, 673–890.

  • Tiedtke, M., 1989: A comprehensive mass flux scheme for cumulus parameterization in large-scale models. Mon. Wea. Rev.,117, 1779–1800.

  • Tripoli, G. J., and W. R. Cotton, 1981: The use of ice-liquid water potential temperature as a thermodynamic variable in deep atmospheric models. Mon. Wea. Rev.,109, 1094–1102.

  • Walko, R. L., W. R. Cotton, M. P. Meyers, and J. Y. Harrington, 1995:New RAMS cloud microphysics parameterization. Part I: The single-moment scheme. Atmos. Res.,38, 29–62.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 1293 842 53
PDF Downloads 336 94 3