Editorial Type:
Article
Article Type:
Research Article

A Quantitative Investigation of Entrainment and Detrainment in Numerically Simulated Cumulonimbus Clouds

Charles Cohen Institute for Global Change Research and Education,* Huntsville, Alabama

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Print Publication:
01 May 2000
DOI:
https://doi.org/10.1175/1520-0469(2000)057<1657:AQIOEA>2.0.CO;2
Page(s):
1657–1674
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Abstract

A method is developed that uses numerical tracers to make accurate diagnoses of entrainment and detrainment rates and of the properties of the entrained and detrained air in numerically simulated clouds. These rates and properties are averaged horizontally and over time, and are produced independently of each other. There are no restrictions on the types of clouds to which the procedure can be applied.

Cumulonimbus clouds are simulated with a variety of initial thermodynamic soundings. In the simulations, updraft entrainment rates are large near and above cloud base, through the entire depth of the conditionally unstable layer. Stronger updrafts in a more unstable environment are better able to entrain relatively undisturbed environmental air, while weaker updrafts in a less unstable environment can entrain only air that has been modified by the clouds.

Smaller convective clouds in more stable environments mix more with their environment but do not necessarily have larger entrainment rates. How much air is entrained depends on the low-level convective available potential energy (CAPE) and on the convective inhibition of the environmental air.

Strong updrafts that are produced when the low-level CAPE is large include parcels with a wide range of equivalent potential temperature and are more likely to have an undilute core and to reach or exceed their level of neutral buoyancy than the weaker and more horizontally uniform updrafts that are produced when low-level CAPE is small.

These results help to explain previous observations that convective updraft cores are stronger in midlatitude continental clouds than they are in tropical maritime clouds.

Corresponding author address: Charles Cohen, Global Hydrology and Climate Center, 977 Explorer Blvd., Huntsville, AL 35806.

Email: charlie.cohen@msfc.nasa.gov

Abstract

A method is developed that uses numerical tracers to make accurate diagnoses of entrainment and detrainment rates and of the properties of the entrained and detrained air in numerically simulated clouds. These rates and properties are averaged horizontally and over time, and are produced independently of each other. There are no restrictions on the types of clouds to which the procedure can be applied.

Cumulonimbus clouds are simulated with a variety of initial thermodynamic soundings. In the simulations, updraft entrainment rates are large near and above cloud base, through the entire depth of the conditionally unstable layer. Stronger updrafts in a more unstable environment are better able to entrain relatively undisturbed environmental air, while weaker updrafts in a less unstable environment can entrain only air that has been modified by the clouds.

Smaller convective clouds in more stable environments mix more with their environment but do not necessarily have larger entrainment rates. How much air is entrained depends on the low-level convective available potential energy (CAPE) and on the convective inhibition of the environmental air.

Strong updrafts that are produced when the low-level CAPE is large include parcels with a wide range of equivalent potential temperature and are more likely to have an undilute core and to reach or exceed their level of neutral buoyancy than the weaker and more horizontally uniform updrafts that are produced when low-level CAPE is small.

These results help to explain previous observations that convective updraft cores are stronger in midlatitude continental clouds than they are in tropical maritime clouds.

Corresponding author address: Charles Cohen, Global Hydrology and Climate Center, 977 Explorer Blvd., Huntsville, AL 35806.

Email: charlie.cohen@msfc.nasa.gov

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  • Alfonso, L., D. Martinez, and C. A. Perez, 1998: Numerical simulations of tropical convective clouds over Cuba using a one-dimensional and time-dependent cloud model. Atmos. Res.,47–48, 343–354.

  • Arakawa, A., and W. H. Schubert, 1974: Interaction of a cumulus cloud ensemble with the large-scale environment, Part I. J. Atmos. Sci.,31, 674–701.

  • Barnes, G. M., J. C. Fankhauser, and W. D. Browning, 1996: Evolution of the vertical mass flux and diagnosed net lateral mixing in isolated convective clouds. Mon. Wea. Rev.,124, 2764–2784.

  • Bermejo, R., and A. Staniforth, 1992: The conversion of semi-Lagrangian advection schemes to quasi-monotone schemes. Mon. Wea. Rev.,120, 2622–2632.

  • Betts, A. K., 1982: Saturation point analysis of moist convective overturning. J. Atmos. Sci.,39, 1484–1505.

  • ——, 1986: A new convective adjustment scheme. Part I: Observational and theoretical basis. Quart. J. Roy. Meteor. Soc.,112, 677–691.

  • ——, and M. J. Miller, 1986: A new convective adjustment scheme. Part II: Single column tests using GATE wave, BOMEX, ATEX and Arctic airmass data sets. Quart. J. Roy. Meteor. Soc.,112, 693–709.

  • Binder, P., 1990: On the parametric representation of the tropospheric thermodynamic structure for mid-latitude convective situations. Quart. J. Roy. Meteor. Soc.,116, 1349–1357.

  • Blanchard, D. O., 1998: Assessing the vertical distribution of convective available potential energy. Wea. Forecasting,13, 870–877.

  • Blyth, A. M., 1993: Entrainment in cumulus clouds. J. Appl. Meteor.,32, 626–641.

  • ——, and D. J. Raymond, 1988: Comparisons between observations of entrainment in Montana cumuli and results from a simple model. J. Atmos. Sci.,45, 1965–1969.

  • ——, W. A. Cooper, and J. B. Jensen, 1988: A study of the source of entrained air in Montana cumuli. J. Atmos. Sci.,45, 3944–3964.

  • Bretherton, C. S., and P. K. Smolarkiewicz, 1989: Gravity waves, compensating subsidence, and detrainment around cumulus clouds. J. Atmos. Sci.,46, 740–759.

  • Brown, R. G., and C. Zhang, 1997: Variability of midtropospheric moisture and its effects on cloud-top height distribution during TOGA COARE. J. Atmos. Sci.,54, 2760–2774.

  • Carpenter, R. L., Jr., K. K. Droegemeier, and A. M. Blyth, 1998a: Entrainment and detrainment in numerically simulated cumulus congestus clouds. Part I: General results. J. Atmos. Sci.,55, 3417–3432.

  • ——, ——, and ——, 1998b: Entrainment and detrainment in numerically simulated cumulus congestus clouds. Part III: Parcel analysis. J. Atmos. Sci.,55, 3440–3455.

  • Cotton, W. R., and G. J. Tripoli, 1978: Cumulus convection in shear flow—Three-dimensional numerical experiments. J. Atmos. Sci.,35, 1503–1521.

  • Cunning, J. B., 1986: The Oklahoma-Kansas preliminary regional experiment for STORM-central. Bull. Amer. Meteor. Soc.,67, 1478–1486.

  • Emanuel, K. A., 1991: A scheme for representing cumulus convection in large-scale models. J. Atmos. Sci.,48, 2313–2335.

  • Fankhauser, J. C., 1971: Thunderstorm–environment interactions determined from aircraft and radar observations. Mon. Wea. Rev.,99, 171–192.

  • Frank, W. M., 1978: The life cycles of GATE convective systems. J. Atmos. Sci.,35, 1256–1264.

  • ——, and J. L. McBride, 1989: The vertical distribution of heating in AMEX and GATE cloud clusters. J. Atmos. Sci.,46, 3464–3478.

  • Grabowski, W. W., 1989: Numerical experiments on the dynamics of the cloud-environment interface: Small cumulus in a shear-free environment. J. Atmos. Sci.,46, 3513–3541.

  • ——, and T. L. Clark, 1991: Cloud-environment interface instability:Rising thermal calculations in two spatial dimensions. J. Atmos. Sci.,48, 527–546.

  • ——, and ——, 1993a: Cloud-environment interface instability. Part II: Extension to three spatial dimensions. J. Atmos. Sci.,50, 555–573.

  • ——, and ——, 1993b: Cloud-environment interface instability. Part III: Direct influence of environmental shear. J. Atmos. Sci.,50, 3821–3828.

  • Grinnell, S. A., C. S. Bretherton, D. E. Stevens, and A. M. Fraser, 1996: Vertical mass flux calculations in Hawaiian trade cumulus clouds from dual-Doppler radar. J. Atmos. Sci.,53, 1870–1886.

  • Johnson, R. H., and P. J. Hamilton, 1988: The relationship of surface pressure features to the precipitation and air flow structure of an intense midlatitude squall line. Mon. Wea. Rev.,116, 1444–1472.

  • Jorgensen, D. P., E. J. Zipser, and M. A. LeMone, 1985: Vertical motions in intense hurricanes. J. Atmos. Sci.,42, 839–856.

  • Kain, J. S., and J. M. Fritsch, 1990: A one-dimensional entraining/detraining plume model and its application in convective parameterization. J. Atmos. Sci.,47, 2784–2802.

  • Kingsmill, D. E., and R. A. Houze Jr., 1999a: Kinematic characteristics of air flowing into and out of precipitating convection over the west Pacific warm pool: An airborne Doppler radar survey. Quart. J. Roy. Meteor. Soc.,125, 1165–1207.

  • ——, and ——, 1999b: Thermodynamic of air flowing into and out of precipitating convection over the west Pacific warm pool. Quart. J. Roy. Meteor. Soc.,125, 1209–1229.

  • Klaassen, G. P., and T. L. Clark, 1985: Dynamics of the cloud-environment interface and entrainment in small cumuli: Two-dimensional simulations in the absence of ambient shear. J. Atmos. Sci.,42, 2621–2642.

  • Klemp, J. B., and R. B. Wilhelmson, 1978: The simulation of three-dimensional convective storm dynamics. J. Atmos. Sci.,35, 1070–1096.

  • Levine, J., 1959: Spherical vortex theory of bubble-like motion in cumulus clouds. J. Meteor.,16, 653–662.

  • Lin, C., and A. Arakawa, 1997a: The macroscopic entrainment processes of simulated cumulus ensemble. Part I: Entrainment sources. J. Atmos. Sci.,54, 1027–1043.

  • ——, and ——, 1997b: The macroscopic entrainment processes of simulated cumulus ensemble. Part II: Testing the entrainment plume model. J. Atmos. Sci.,54, 1044–1053.

  • Lucas, C., E. J. Zipser, and M. A. LeMone, 1994a: Vertical velocity in oceanic convection off tropical Australia. J. Atmos. Sci.,51, 3183–3193.

  • ——, ——, and ——, 1994b: Convective available potential energy in the environment of oceanic and continental clouds: Corrections and comments. J. Atmos. Sci.,51, 3829–3830.

  • ——, ——, and ——, 1996: Reply. J. Atmos. Sci.,53, 1212–1214.

  • Mapes, B. E., 1993: Gregarious tropical convection. J. Atmos. Sci.,50, 2026–2037.

  • Martner, B. E., J. D. Marwitz, and R. A. Kropfli, 1992: Radar observations of transport and diffusion in clouds and precipitation using TRACIR. J. Atmos. Oceanic Technol.,9, 226–241.

  • McBride, J. L., and W. M. Frank, 1999: Relationships between stability and monsoon convection. J. Atmos. Sci.,56, 24–36.

  • Mesinger, F., and A. Arakawa, 1976: Numerical methods used in atmospheric models. GARP Publ. Ser. 17, WMO-ICSU Joint Organizing Committee, 64 pp.

  • Michaud, L. M., 1996: Comments on “Convective available potential energy in the environment of oceanic and continental clouds.” J. Atmos. Sci.,53, 1209–1211.

  • Nicholls, M. E., and M. J. Weissbluth, 1988: A comparison of two-dimensional and quasi-three-dimensional simulations of a tropical squall line. Mon. Wea. Rev.,116, 2437–2452.

  • Perry, K. D., and P. V. Hobbs, 1996: Influences of isolated cumulus clouds on the humidity of their surroundings. J. Atmos. Sci.,53, 159–174.

  • Petersen, W. A., and Coauthors, 1999: Mesoscale and radar observations of the Fort Collins flash flood of 28 July 1997. Bull. Amer. Meteor. Soc.,80, 191–216.

  • Pielke, R. A., 1974: A comparison of three-dimensional and two-dimensional numerical predictions of sea breezes. J. Atmos. Sci.,31, 1577–1585.

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

  • Randall, D. A., and J. Wang, 1992: The moist available energy of a conditionally unstable atmosphere. J. Atmos. Sci.,49, 240–255.

  • Rasch, P. J., and D. L. Williamson, 1990: Computational aspects of moisture transport in global models of the atmosphere. Quart. J. Roy. Meteor. Soc.,116, 1071–1090.

  • Raymond, D. J., and A. M. Blyth, 1986: A stochastic mixing model for nonprecipitating cumulus clouds. J. Atmos. Sci.,43, 2708–2718.

  • ——, and ——, 1992: Extension of the stochastic mixing model to cumulonimbus clouds. J. Atmos. Sci.,49, 1968–1983.

  • ——, R. Solomon, and A. M. Blyth, 1991: Mass fluxes in New Mexico mountain thunderstorms from radar and aircraft measurements. Quart. J. Roy. Meteor. Soc.,117, 587–621.

  • Reuter, G. W., and M. K. Yau, 1987: Mixing mechanisms in cumulus congestus clouds. Part II: Numerical simulations. J. Atmos. Sci.,44, 798–827.

  • Rutledge, S. A., R. A. Houze Jr., M. I. Biggerstaff, and T. Matejka, 1988: The Oklahoma-Kansas mesoscale convective system of 10–11 June 1985: Precipitation structure and single-Doppler radar analysis. Mon. Wea. Rev.,116, 1409–1430.

  • Schlesinger, R. E., 1984: Effects of the pressure perturbation field in numerical models of unidirectionally sheared thunderstorm convection: Two versus three dimensions. J. Atmos. Sci.,41, 1571–1587.

  • Scorer, R. S., and F. H. Ludlam, 1953: Bubble theory of penetrative convection. Quart. J. Roy. Meteor. Soc.,79, 94–103.

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

  • ——, and A. A. M. Holtslag, 1996: Model impacts of entrainment and detrainment rates in shallow cumulus convection. J. Atmos. Sci.,53, 2354–2364.

  • Simpson, J., R. H. Simpson, D. A. Andrews, and M. A. Eaton, 1965:Experimental cumulus dynamics. Rev. Geophys.,3, 387–431.

  • Stith, J. L., 1992: Observations of cloud-top entrainment in cumuli. J. Atmos. Sci.,49, 1334–1347.

  • Stommel, H., 1947: Entrainment of air into a cumulus cloud. J. Meteor.,4, 91–94.

  • ——, 1951: Entrainment of air into a cumulus cloud II. J. Meteor.,8, 127–129.

  • Tao, W.-K., and J. Simpson, 1989: Modeling study of a tropical squall-type convective line. J. Atmos. Sci.,46, 177–202.

  • Taylor, G. R., and M. B. Baker, 1991: Entrainment and detrainment in cumulus clouds. J. Atmos. Sci.,48, 112–121.

  • Thorpe, A. J., M. J. Miller, and M. W. Moncrieff, 1980: Dynamical models of two-dimensional downdraughts. Quart. J. Roy. Meteor. Soc.,106, 463–484.

  • ——, ——, and ——, 1982: Two-dimensional convection in non-constant shear: A model of mid-latitude squall lines. Quart. J. Roy. Meteor. Soc.,108, 739–762.

  • Tremback, C. J., J. Powell, W. R. Cotton, and R. A. Pielke, 1987: The forward-in-time upstream advection scheme: Extension to higher orders. Mon. Wea. Rev.,115, 540–555.

  • 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.

  • ——, and ——, 1982: The Colorado State University three-dimensional cloud/mesoscale model—1982. Part I: General theoretical framework and sensitivity experiments. J. Rech. Atmos.,16, 185–219.

  • Turner, J. S., 1962: The “starting plume” in neutral surroundings. J. Fluid Mech.,13, 356–368.

  • Vaillancourt, P. A., M. K. Yau, and W. W. Grabowski, 1997: Upshear and downshear evolution of cloud structure and spectral properties. J. Atmos. Sci.,54, 1203–1217.

  • 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.

  • Wang, C., and R. G. Prinn, 1998: Impact of the horizontal wind profile on the convective transport of chemical species. J. Geophys. Res.,103, 22 063–22 071.

  • Wang, J., and D. A. Randall, 1994: The moist available energy of a conditionally unstable atmosphere. Part II: Further analysis of GATE data. J. Atmos. Sci.,51, 703–710.

  • Wei, D., A. M. Blyth, and D. J. Raymond, 1998: Buoyancy of convective clouds in TOGA COARE. J. Atmos. Sci.,55, 3381–3391.

  • Wilson, J. W., N. A. Crook, C. K. Mueller, J. Sun, and M. Dixon, 1998: Nowcasting thunderstorms: A status report. Bull. Amer. Meteor. Soc.,79, 2079–2099.

  • Yanai, M., S. Esbensen, and J.-H. Chu, 1973: Determination of bulk properties of tropical cloud clusters from large-scale heat and moisture budgets. J. Atmos. Sci.,30, 611–627.

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