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Boundary-Layer Meteorology

, Volume 121, Issue 2, pp 313–338 | Cite as

Combining Non-local Scalings with a TKE Closure for Mixing in Boundary-layer Clouds

  • Adrian Lock
  • Jocelyn Mailhot
Original Article

Abstract

A new approach to the parametrization of the cumulus-capped boundary layer is described. It combines a traditional higher-order turbulence closure, appropriate for boundary layers where the skewness of thermodynamic variable probability distributions is low (typically stratocumulus-capped), with non-local scaled similarity functions. These are introduced in order to represent explicitly that part of the distribution arising from skewed cumulus elements and the scalings are found to work very well against equilibrium shallow cumulus large-eddy simulations. Results from a wide range of single column model simulations, from stratocumulus to shallow cumulus to cumulus rising into stratocumulus, are presented that demonstrate the validity of the approach as a means of parametrizing the cloudy boundary layer. Sensitivity tests show that enhancement of the turbulence length scales and the buoyancy production of TKE are especially important.

Keywords

Boundary-layer clouds Non-local closure Similarity scaling TKE closure 

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References

  1. Bechtold P, Cuijpers JWM, Mascart P, Trouilhet P (1995) Modeling of trade wind cumuli with a low-order turbulence model: towards a unified description of Cu and Sc clouds in meteorological models. J Atmos Sci 52: 455–463CrossRefGoogle Scholar
  2. Bechtold P, Siebesma P (1998) Organization and representation of boundary layer clouds. J Atmos Sci 55:888–895CrossRefGoogle Scholar
  3. Belair S, Mailhot J, Strapp J, MacPherson JI (1999) An examination of local versus nonlocal aspects of a TKE based boundary layer scheme in clear convective conditions. J. Appl. Meteorol. 38:1499–1518CrossRefGoogle Scholar
  4. Brown AR, Cederwall RT, Chlond A, Duynkerke PG, Golaz J-C, Khairoutdinov M, Lewellen DC, Lock AP, MacVean MK, Moeng C-H, Neggers RAJ, Siebesma AP, Stevens B (2002) Large-eddy simulation of the diurnal cycle of shallow cumulus convection over land. Quart J Roy Meteorol Soc 128: 1075–1093CrossRefGoogle Scholar
  5. Bougeault P, Lacarrere P (1989) Parametrization of orography-induced turbulence in a mesobeta-scale model. Mon. Wea. Rev. 117: 1872–1890CrossRefGoogle Scholar
  6. Cuijpers JWM, Bechtold P (1995) A simple parametrization of cloud water related variables for use in boundary layer models. J Atmos Sci 52: 2486–2490CrossRefGoogle Scholar
  7. Duynkerke PG, de Roode SR, van Zanten MC, Calvo J, Cuxart J, Cheinet S, Chlond A, Grenier H, Jonker PJ, Kohler M, Lenderink G, Lewellen D, Lappen C-L, Lock AP, Moeng C-H, Muller F, Olmeda D, Piriou J-M, Sanchez E, Sednev I (2004) Observations and numerical simulations of the diurnal cycle of the EUROCS stratocumulus case. Quart J Roy Meteorol Soc 130: 3269–3296CrossRefGoogle Scholar
  8. Grant ALM, Brown AR (1999) A similarity hypothesis for cumulus transports. Quart J Roy Meteorol Soc 125: 1913–1935CrossRefGoogle Scholar
  9. Grant ALM (2001) Cloud base fluxes in the cumulus-capped boundary layer. Quart J Roy Meteorol Soc 127: 407–421CrossRefGoogle Scholar
  10. Grant ALM, Lock AP (2004) The turbulent kinetic energy budget for shallow convection. Quart J Roy Meteorol Soc 130: 401–422CrossRefGoogle Scholar
  11. Lenderink G, Holtslag AAM (2004) An updated length scale formulation for turbulent mixing in clear and cloudy boundary layers. Quart J Roy Meteorol Soc 130: 3405–3427CrossRefGoogle Scholar
  12. Lenderink G, Siebesma AP, Cheinet S, Irons S, Jones CG, Marquet P, Muller F, Olmeda D, Calvo J, Sanchez E, Soares PMM (2004) The diurnal cycle of shallow Cumulus clouds over land: A single column model intercomparison study. Quart J Roy Meteorol Soc 130:3339–3364CrossRefGoogle Scholar
  13. Lock AP (1998) The parametrization of entrainment in cloudy boundary layers. Quart J Roy Meteorol Soc 124: 2729–2753CrossRefGoogle Scholar
  14. Lock AP, MacVean MK (1999a) The parametrization of entrainment driven by surface heating and cloud-top cooling. Quart J Roy Meteorol Soc 125: 271–299CrossRefGoogle Scholar
  15. Lock AP, MacVean MK (1999b) The generation of turbulence and entrainment by buoyancy reversal. Quart J Roy Meteorol Soc 125: 1017–1038CrossRefGoogle Scholar
  16. Lock AP, Brown AR, Bush MR, Martin GM, Smith RNB (2000) A new boundary layer mixing scheme. Part I: Scheme description and single-column model tests. Mon. Wea. Rev. 128: 3187–3199CrossRefGoogle Scholar
  17. Lock AP (2001) The numerical representation of entrainment in parametrizations of boundary layer turbulent mixing. Mon. Wea. Rev. 129: 1148–1163CrossRefGoogle Scholar
  18. Mailhot J, Lock AP (2004) An examination of several parametrizations of mixing lengths in a stable boundary layer: the GABLS case. In proceedings of the 16th Symposium on Boundary Layers and Turbulence, Portland, USA, AMS, http://ams.confex.com/ams/BLTAIRSE/techprogram/paper_78738.htmGoogle Scholar
  19. Ricard JL, Royer JF (1993) A statistical cloud scheme for use in an AGCM. Annales Geophysicae 11:1095–1115Google Scholar
  20. Siebesma AP, Bretherton CS, Brown AR, Chlond A, Cuxart J, Duynkerke PG, Lewellen DC, MacVean MK, Neggers RAJ, Sanchez E, Siebesma AP, Stevens DE (2003) A large eddy simulation intercomparison study of shallow cumulus convection. J Atmos Sci 60: 1201–1219CrossRefGoogle Scholar
  21. Stevens B, Ackerman AS, Albrecht BC, Brown AR, Chlond A, Cuxart J, Duynkerke PG, Lewellen DC, MacVean MK, Sanchez E, Siebesma AP, Stevens DE (2000). Simulations of trade-wind cumuli under a strong inversion. J Atmos Sci 58: 1870–1891CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2006

Authors and Affiliations

  1. 1.Met OfficeExeterUK
  2. 2.RPNDorvalCanada

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