Scientific Results

Stability functions for momentum, heat and water vapour and the vertical transport of TKE and pressure fluctuations estimated from measured vertical profiles of wind speed, temperature and humidity

Year: 1996

Authors: Kramm G., Herbert F., Bernhardt K., Müller H., Werle P., Foken T., Richter S.H.

Autors Affiliation: Fraunhofer-Inst. F. Atmosph. U., 82467 Garmisch-Partenkirchen, Germany; Inst. F. Meteorologie und Geophysik, Johann Wolfgang Goethe-Univ., Postfach 111932, 60054 Frankfurt am Main, Germany; Leibniz-Sozietät e.V., Postfach 34, 12563 Berlin, Germany; Deutscher Wetterdienst, Meteorologisches Observatorium L., Dezernat Landoberflachenprozesse/G., 15864 Lindenberg, Germany

Abstract: Vertical wind speed, temperature and humidity profile data from three known atmospheric field campaigns are used to determine the surface layer similarity functions for the transport of momentum and heat as well as TKE (turbulent kinetic energy) and pressure fluctuations. The basic principles on which we carry out this determination are a simplified TKE-budget equation obeying Monin-Obukhov similarity laws and a one-and-a-half-order closure concept. Least squares techniques are utilised for the calculations. The numerical analysis provides all important internal and external surface layer parameters like the friction velocity, u*, the temperature and humidity scales, T* and q*, the roughness length, z o , the zero-plane displacement, d, as well as the temperature and humidity values T r and q r at the height z r = z o + d. With these data we can determine the individual ?-coefficients in the empirical Businger-Dyer and O\’KEYPS relations. This is the main interest of this study. It is found that the computed empirical coefficients appreciably depend on the thermal stratification in the atmospheric surface layer. These estimates document that the ?\’s apparently vary so considerable within a stability regime that the usually adopted constant coefficients were not suitable in these cases. Moreover, one is led to the further important result that the parameters z o and d found here, considerably differ from those values obtained with the conventional ?-coefficients suggested in the literature.

Journal/Review:

Volume: 69 (4)      Pages from: 463  to: 475

KeyWords: boundary layer; humidity; Monin-Obukhov theory; temperature; thermal stratification; turbulent kinetic energy; wind velocity
DOI: 10000000000

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