Abstract
The internal thermal boundary layer developing over the Mediterranean during a cold-air outbreak associated with a Tramontane event has been studied by means of airborne lidar, in situ sensors, and a modelling approach that consisted of nesting the University of Washington (UW) planetary boundary-layer (PBL) model in an advective zero-order jump model. This approach bypasses some of the deficiencies associated with each model: the absence of the dynamics in the mixed layer for the zero-order jump model and the lack of an inversion at the PBL top for the UW PBL model. Particular attention is given to the parameterization of the entrainment flux at the PBL top. Values of the entrainment closure parameter derived with the model when matching PBL structure observations are much lower than those derived with standard zero-order jump models. They also are in good agreement with values measured in different meteorological situations by other studies. This improvement is a result of the introduction of turbulent kinetic energy production in the mixed layer.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Barr, A. G. and Betts, A. K.: 1997, ‘Radiosonde Boundary Layer above a Boreal Forest’, J. Geophys. Res. 102, 29,205-29,212.
Betts, A. K., Desjardins, R. L., and MacPherson, J. I.: 1992, ‘Budget Analysis of the Boundary Layer Grid during FIFE 1987’, J. Geophys. Res. 97, 533-546.
Betts, A. K. and Ball, H.: 1994, ‘Budget Analysis of FIFE 1987 Sonde Data’, J. Geophys. Res. 99, 3655-3666.
Betts, A. K. and Barr, A. G.: 1996, ‘First International Satellite Land Surface Climatology Field Experiment 1987 Sonde Budget Revisited’, J. Geophys. Res. 101, 23,285-23,288.
Boers, R., Eloranta E. W., and Coulter R. L.: 1984, ‘Lidar Observations of Mixed Layer Dynamics: Tests of Parametrized Entrainment Models of Mixed Layer Growth Rate’, J. Clim. Appl. Meteorol. 23, 247-266.
Boers, R. and Melfi, S.H.: 1987, ‘Cold-Air Outbreak during MASEX: Lidar Observations and Boundary Layer Model Test’, Boundary-Layer Meteorol. 39, 41-51.
Boers, R., Melfi, S. H., and Palm, S. P.: 1991, ‘Cold-Air Outbreak during GALE: Lidar Observations and Modelling of Boundary Layer Dynamics’, Mon. Wea. Rev. 119, 1132-1150.
Bougeault, P., Jansa Clar, A., Benech, B., Carissimo, B., Pelon, P., and Richard, E.: 1990, ‘Momentum Budget over the Pyrénées: The PYREX Experiment’, Bull. Amer. Meteorol. Soc. 71, 806-818.
Bougeault, P., Jansa Clar, A., Beau, I., Benech, B., Benoit, R., Bessemoulin, P., Caccia, J. L., Campins, J., Carissimo, B., Champeaux, J. L., Crochet, M., Druilhet, A., Durand, P., Elkalfi, A., Flamant, P. H., Genoves, A., Georgelin, M., Hoinka, K. P., Klaus, V., Koffi, E., Krotoni, V., Mazaudier, C., Pelon, J., Petitdidier, M., Pointin, Y., Richard, E., Satumora, T., Stein, S., and Tannhauser, D.: 1993, ‘The Atmospheric Momentum Budget over a Major Mountain Range: First Results of the PYREX Field Program’, Annales Geophysicae 11, 395-418.
Bougeault, P., Benech, B., Bessemoulin, P., Carissimo, B., Jansa Clar, Pelon, J., Petitdidier, M., and Richard, E.: 1997, ‘PYREX: A Summary of Findings’, Bull. Amer. Meteorol. Soc. 78, 637-650.
Brown, R. A.: 1970, ‘A Secondary Flow Model for the Planetary Boundary Layer’, J. Atmos. Sci. 27, 742-757.
Brown, R. A.: 1972, ‘On the Inflection Point Instability of the Stratified Ekman Boundary Layer’, J. Atmos. Sci. 29, 850-859.
Brown, R. A.: 1980, ‘Longitudinal Instabilities and Secondary Flows in the Planetary Boundary-Layer: A Review’, Rev. Geophys. Space Phys. 18, 683-697.
Brown, R. A. and Liu, W. T.: 1982, ‘An Operational Large-Scale Marine Planetary Boundary-Layer Model’, J. Appl. Meteorol. 21, 261-269.
Brown, R. A.: 1991, Fluid Mechanics of the Atmosphere, International Geophysics Series, Vol. 47, Academic Press, 460 pp.
Brümmer B., Rump, B., and Kruspe, G.: 1992, ‘A Cold-Air Outbreak Near Spitsbergen in Springtime-Boundary-Layer Modification and Cloud Development’, Boundary-Layer Meteorol. 61, 13-46.
Bunker A. F.: 1976, ‘Heat and Vapor Fluxes in Air Flowing Southward over the North Atlantic Ocean’, J. Appl. Meteorol. 17, 52-63.
Campins, J., Jansa Clar, A., Benech, B., Koffi, E., and Bessemoulin, P.: 1995, ‘Pyrex Observation and Model Diagnosis of the Tramontane Wind’, Meteorol. Atmos. Phys. 56, 209-228.
Chou, S. H. and Zimmerman, J.: 1989, ‘Bivariate Condtional Slampling of Buoyancy Flux during an Intense Cold-Air Outbreak’, Boundary-Layer Meteorol. 46, 93-112.
Chou, S. H. and Fergusson, M. P.: 1991, ‘Heat Flux and Roll Circulation over the Western Gulf Stream during an Intense Cold-Air Outbreak’, Boundary-Layer Meteorol. 55, 255-281.
Driedonks, A. G. M.: 1982, ‘Models and Observations of the Growth of the Atmospheric Boundary Layer’, Boundary-Layer Meteorol. 23, 283-306.
Dubosclard, G.: 1980, ‘A Comparison between Observed and Predicted Values of the Entrainment Coefficient in the Planetary Boundary Layer’, Boundary-Layer Meteorol. 18, 473-483.
Dyer, A. J.: 1974, ‘A Review of Flux-Profile Relationships’, Boundary-Layer Meteorol. 7, 363-372.
Eting, D. and Brown, R. A.: 1993, ‘Roll Vortices in the Planetary Boundary Layer: A Review’, Boundary-Layer Meteorol. 65, 215-248.
Flamant, C. and Pelon, J.: 1996, ‘Atmospheric Boundary-Layer Structure over the Mediterranean during a Tramontane Event’, Quart. J. Roy. Meteorol. Soc. 122, 1741-1778.
Flamant, C., Pelon, J., Flamant, P. H., and Durand, P.: 1997, ‘Lidar Determination of the Entrainment Zone Thickness at the Top of the Unstable Marine Atmospheric Boundary Layer’, Boundary-Layer Meteorol. 83, 247-284.
Foster R. C.: 1997, ‘Structure and Energetics of the Optimal Ekman Layer Perturbations’, J. Fluid Mech. 333, 97-123.
Garratt, J. R., Hess, G. D., Physick, W. L., and Bougeault, P.: 1996, ‘The Atmospheric Boundary Layer — Advances in Knowledge and Application’, Boundary-Layer Meteorol. 78, 9-37.
Georgelin, M. and Richard, E.: 1996, ‘Numerical Simulation of the Flow Dispersion around the Pyrénées: A Tramontana Case Study’, Mon. Wea. Rev. 124, 687-700.
Grisogono, B.: 1995, ‘A Generalized Ekman Layer Profile with Gradually Varying Eddy Diffusivity’, Quart. J. Roy. Meteorol. Soc. 121, 445-453.
Gryning, S. and Batchvarova, E.: 1990, ‘Analytical Model for the Growth of the Coastal Internal Boundary Layer during a Offshore Flow’, Quart. J. Roy. Meteorol. Soc. 116, 187-203.
Hein, P. F. and Brown, R. A.: 1988, ‘Observation of Longitudinal Roll Vortices during Artic Cold-Air Outbreaks over Open Water’, Boundary-Layer Meteorol. 45, 177-199.
LeMone, M. A.: 1973, ‘The Structure and Dynamics of the Horizontal Roll Vortices in the Planetary Boundary Layer’, J. Atmos. Sci. 30, 1077-1091.
Moeng, C.-H. and Sullivan, P. P.: 1994, ‘A Comparison of Shear-and Buoyancy-Driven Planetary Boundary-Layer Flows’, J. Atmos. Sci. 51, 999-1022.
Musson-Genon, L.: 1995, ‘Comparison of Different Simple Turbulence Closures with a One-Dimensional Boundary-Layer Model’, Mon. Wea. Rev. 123, 163-180.
Niiler, P. P.: 1975, ‘Deepening of the Wind-Mixed Layer’, J. Mar. Res. 33, 405-422.
Raasch, S.: 1990, ‘Numerical Simulation of the Development of the Convective Boundary Layer during a Cold-Air Outbreak’, Boundary-Layer Meteorol. 52, 349-375.
Randall, D. A.: 1984, ‘Buoyant Production and Consumption of Turbulence Kinetic Energy in Cloud-Topped Mixed Layers’, J. Atmos. Sci. 41, 402-413.
Stage, S. A. and Businger, J. A.: 1981, ‘A Model for Entrainment into a Cloud-Topped Marine Boundary Layer. Part I: Model Description and Application to a Cold-Air Outbreak Episode’, J. Atmos. Sci. 38, 2213-2229.
Stull, R. B.: 1976, ‘The Energetics of Entrainment Across a Density Interface’, J. Atmos. Sci. 33, 1260-1267.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Flamant, C., Pelon, J., Brashers, B. et al. Evidence of a Mixed-Layer Dynamics Contribution to the Entrainment Process. Boundary-Layer Meteorology 93, 47–73 (1999). https://doi.org/10.1023/A:1002083425811
Issue Date:
DOI: https://doi.org/10.1023/A:1002083425811