The Influence of Thermal Effects on the Wind Speed Profile of the Coastal Marine Boundary Layer
The wind speed profile in a coastal marine environment is investigated with observations from the measurement program Rødsand, where meteorological data are collected with a 50 m high mast in the Danish Baltic Sea, about 11 km from the coast. When compared with the standard Monin—Obukhov theory the measured wind speed increase between 10 m and 50 m height is found to be systematically larger than predicted for stable and near-neutral conditions. The data indicate that the deviation is smaller for short (10–20 km) distances to the coast than for larger (>30 km) distances.
The theory of the planetary boundary layer with an inversion lid offers a qualitative explanation for these findings. When warm air is advected over colder water, a capping inversion typically develops. The air below is constantly cooled by the water and gradually develops into a well-mixed layer with near-neutral stratification. Typical examples as well as scatter plots of the data are consistent with this explanation. The deviation of measured and predicted wind speed profiles is shown to be correlated with the estimated height and strength of the inversion layer.
Unable to display preview. Download preview PDF.
- Businger, J. A., Wyngaard, J. C., Izumi, Y., and Bradley, E. F.: 1971, ‘Flux-Profile Relationships in the Atmospheric Surface Layer’, J. Atmos. Sci. 28, 181–189.Google Scholar
- Charnock, H.: 1955, ‘Wind Stress over a Water Surface’, Quart. J. Roy. Meteorol. Soc. 81, 639–640.Google Scholar
- Garratt, J. R.: 1994, The Atmospheric Boundary Layer, Cambridge University Press, Cambridge, 316 pp.Google Scholar
- Geernaert, G. and Larsen, S.: 1993, ‘On the Role of Humidity in Estimating Marine Surface Layer Stratification and Scaterometer Cross Section’, J. Geophys. Res. 98(C1), 927–932.Google Scholar
- Højstrup, J.: 1999, ‘Vertical Extrapolation of Offshore Wind Profiles’, in E. L. Petersen, P. Hjuler Jensen, K. Rave, P. Helm, and H. Ehmann (eds.), Wind Energy for the Next Millennium. Proceedings. 1999 European Wind Energy Conference (EWEC '99), Nice, FR, March 1-5, 1999, James and James Science Publishers, London, U.K., pp. 1220–1223.Google Scholar
- Källstrand, B.: 1998, ‘Low Level Jets in a Marine Boundary Layer during Spring’, Contr. Atmos. Phys. 71, 359–373.Google Scholar
- Lange, B., Barthelmie, R. J., and Højstrup, J.: 2001, Description of the Rødsand Field Measurement, Report Risø-R-1268, Risø National Laboratory, 4000 Roskilde, DK, 60 pp.Google Scholar
- Lange, B., Johnson, H.K., Larsen, S., Højstrup, J., Kofoed-Hansen, H., and Yelland, M. J.: 2004, ‘On Detection of a Wave Age Dependency for the Sea Surface Roughness’, J. Phys. Oceanog., in press.Google Scholar
- Larsen, S. E.: 1993, ‘Observing and Modelling the Planetary Boundary Layer’, in E. Raschke and D. Jacob (eds.), Energy and Water Cycles in the Climate System, NATO ASI series I, Volume 5, Springer-Verlag, Berlin, Heidelberg, pp. 365–418.Google Scholar
- Lenschow D. H., Li X. S., Zhu C. J., and Stankov, B. B.: 1988, ‘The Stably Stratified Boundary Layer over the Great Plains, I, Mean and Turbulence Structure’, Boundary-Layer Meteorol. 42, 95–121.Google Scholar
- Mortensen, N. G., Landberg L., Troen, I., and Petersen, E. L.: 1993, Wind Analysis and Application Program (WASP)-User's Guide, Report Risø-I-666(EN) (v.2), Risø National Laboratory, 4000 Roskilde, Denmark, 133 pp.Google Scholar
- Panofsky, H. A.: 1973, ‘Tower Micrometeorology’, in D. A. Haugen (ed.), Workshop on Micrometeorology, American Meteorological Society, Boston, 151–176.Google Scholar
- Tennekes, H.: 1982, ‘Similarity Relations, Scaling Laws and Spectral Dynamics’, in F. T. M. Nieuwstadt and H. van Dop (eds.), Atmospheric Turbulence and Air Pollution Modelling, Reidel, Hingham, MA, pp. 37–68.Google Scholar
- Tjernström, M., and Smedman, A.-S.: 1993, ‘The Vertical Turbulence Structure of the Coastal Marine Atmospheric Boundary Layer’, J. Geophys. Res. 98(C3), 4809–4826.Google Scholar
- Wu, J.: 1980, ‘Wind Stress Coefficients over Sea Surface near Neutral Conditions-A Revisit’, J. Phys. Oceanogr. 10, 727–740.Google Scholar
- Wyngaard, J. C.: 1973, ‘On Surface-Layer Turbulence’, in D. A. Haugen (ed.), Workshop on Micrometeorology, American Meteorological Society, Boston, pp. 101–149.Google Scholar