Résumé
Une méthode de détermination expérimentale du coefficient d'entraînement % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeyqaiabg2% da9iabgkHiTiaacIcadaqdaaqaaiabeI7aXjaacEcacaWG3bGaai4j% aaaacaGGPaGaamyAaiabg+caViaacIcadaqdaaqaaiabeI7aXjaacE% cacaWG3bGaai4jaaaacaGGPaWaaSbaaSqaaiaaicdaaeqaaaaa!4646!\[{\text{A}} = - (\overline {\theta 'w'} )i/(\overline {\theta 'w'} )_0 \] dans une couche limite planétaire convective est proposée. Cette méthode, qui combine les données enregistrées par un sodar à des mesures météorologiques in situ, s'applique aux cas de convection matinale (couche de mélange assez peu développée surmontée par une inversion de température marquée.) Dans le cas des observations recueillies lors de la campagne de Voves (1977) elle fournit des valeurs de A qui s'écartent parfois de 0.2 ± 0.1 (gamme des valeurs souvent adoptées) et couvrent la totalité de l'intervalle 0-1.
La comparaison entre les valeurs de A déterminées par cette méthode et celles prédites à partir des modèles de Stull (1976) et Zeman (1977) conduit à un accord satisfaisant, ce qui confirme le rôle joué par la turbulence mécanique dans le processus d'entraînement durant les premières heures de la convection matinale.
Abstract
A new method is presented for determining experimentally the entrainment coefficient % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeyqaiabg2% da9iabgkHiTiaacIcadaqdaaqaaiabeI7aXjaacEcacaWG3bGaai4j% aaaacaGGPaGaamyAaiabg+caViaacIcadaqdaaqaaiabeI7aXjaacE% cacaWG3bGaai4jaaaacaGGPaWaaSbaaSqaaiaaicdaaeqaaaaa!4646!\[{\text{A}} = - (\overline {\theta 'w'} )i/(\overline {\theta 'w'} )_0 \] characteristic of a convective, planetary boundary layer. This method, which makes use of sodar records together with simultaneous meteorological observations, can be applied to morning convection situations (i.e. shallow mixed layer capped by a marked temperature inversion). Data from the Voves experiment (France, summer 1977) yield A values between 0 and 1, thus departing from the 0.2 ± 0.1 interval which is the range of commonly accepted values.
A comparison between these results and theoretical predictions using models developed by Stull (1976) and Zeman and Tennekes (1977) indicates a fair amount of agreement; the importance of mechanically driven turbulence in the entrainment process, especially for the early morning hours, is therefore confirmed.
This is a preview of subscription content, log in via an institution to check access.
References
André, J. C., De Moor, G., Laccarère, P., and Du Vachat, R.: 1976, ‘Turbulence Approximation for Inhomogeneous Flows: Part II. The Numerical Simulation of a Penetrative Convection Experiment’, J. Atmos. Sci. 33, 482–491.
Cattle, H. and Weston, K. J.: 1975, ‘Budget Studies of Heat Flux Profiles in the Convective Boundary Layer Over Land’, Quart. J. Roy. Meteorol. Soc. 101, 353–363.
Cordesses, R. and Dubosclard, G.: 1974, ‘A Display System for an Acoustic Radar’, IEEE Trans. Geosci. Electron. GE-12, 140–145.
Dubosclard, G.: 1977, ‘Observations de la Convection Matinale Par Sodar’. Proceedings: Colloque de l' Union Radio Scientifique Internationale, 541–545, La Baule (France).
Estival, A. and Aubry, M.: 1976, ‘Interprétation des Echos Sodar en Termes de Stratification Atmosphérique’. La Météorologie VI5, 33–42.
Frisch, A. S. and Clifford, S. F.: 1974, ‘A Study of Convection Capped by a Stable Layer Using Doppler Radar and Acoustic Echo Sounders’, J. Atmos. Sci. 31, 1622–1628.
Hall, F. F., Edinger, J. G., and Neff, W. D.: 1975, ‘Convectives Plumes in the Planetary Boundary Layer, Investigated with an Acoustic Echo Sounder’, J. Appl. Meteorol. 14, 513–523.
Kaimal, J. C., Wyngaard, J. C., Haugen, D. A., Coté, O. R., and Izumi, Y.: 1976, ‘Turbulence Structure in The Convective Boundary Layer’, J. Atmos. Sci. 33, 2152–2169.
Klapisz, C. and Weill, A.: 1978, ‘Modèle Semi-Empirique d'Evolution Matinale du Profil de Vent Entre le Sol et le Sommet de l'Inversion’, J. Rech. Atmos. 12, 113–117.
Klöppel, M., Stilke, G., and Wamser, C.: 1978, ‘Experimental Investigations into Variations of Ground-Based Inversions and Comparisons with Results of Simple Boundary-Layer Models’, Boundary-Layer Meteorol. 15, 135–146.
Lenschow, D. H.: 1974, ‘Model of the Height Variation of the Turbulence Kinetic Energy Budget in the Unstable Planetary Boundary Layer’, J. Atmos. Sci. 31, 465–474.
Neff, W. D.: 1975, ‘Quantitative Evaluation of Acoustic Echoes From the Planetary Boundary Layer’, Tech. Rep. ERL 322-WPL 38, Natl. Oceanic and Atmos. Admin., Boulder, Colo.
Rayment, R. and Readings, C. J.: 1974, ‘A Case Study of the Structure and Energetics of an Inversion’, Quart. J. Roy. Meteorol. Soc. 100, 221–233.
Stull, R. B.: 1976, ‘The Energetics of Entrainment Across a Density Interface’, J. Atmos. Sci. 33, 1260–1267.
Tennekes, H.: 1973, ‘A Model for the Dynamics of the Inversion Above a Convective Boundary Layer’, J. Atmos. Sci. 30, 558–567.
Weill, A., Eymard, L., Lequere, M. E., Klapisz, C., Baudin, F. and van Grunderbeeck, P.: 1978, ‘Investigation of the Planetary Boundary Layer With an Acoustic Doppler Sounder’, Preprints of the 4th Symposium on Meteorological Observations and Instrumentation, pp. 415–421, American Meteorological Society, Boston, Mass.
Willis, G. E. and Deardorff, J. W.: 1974, ‘A Laboratory Model of the Unstable Planetary Boundary Layer’, J. Atmos. Sci. 31, 1297–1307.
Wood, N. L. H.: 1977, ‘A Field Study on the Representativeness of Turbulent Fluxes of Heat and Water Vapour at Various Sites in Southern England’, Quart. J. Roy. Meteorol. Soc. 103, 617–624.
Zeman, O.: 1975, ‘The Dynamics of Entrainment in the Planetary Boundary Layer: a Study in Turbulence Modeling and Parameterization’, Ph. D. Thesis, The Pennsylvania State University.
Zeman, O. and Tennekes, H.: 1977, ‘Parameterization of the Turbulent Energy Budget at the Top of the Daytime Atmospheric Boundary Layer’, J. Atmos. Sci. 34, 111–123.
Zilitinkevich, S. S.: 1975, ‘Comments on the Paper by H. Tennekes’, J. Atmos. Sci. 32, 991–992.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Dubosclard, G. A comparison between observed and predicted values for the entrainment coefficient in the planetary boundary layer. Boundary-Layer Meteorol 18, 473–483 (1980). https://doi.org/10.1007/BF00119500
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00119500