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Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. 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
 Contributions to atmospheric physics 69 (1996), Nr.4, S.463475 ISSN: 00058173 ISSN: 03034186 

 Englisch 
 Zeitschriftenaufsatz 
 Fraunhofer IFU; 2002 in HelmholtzGesellschaft integriert 
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 TKEbudget equation obeying Monin0bukhov similarity laws and a oneandahalforder 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, Theta *. and q *, the roughness length, z 0., the zeroplane displacement, d, as well as the temperature and humidity values Theta gamma and q gamma, at the height z gamma = z0 + d. With these data we can determine the individual gammacoefficients in the empirical BusingerDyer and O'keyps relations. This is the main inte rest 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 gamma'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 z0 and d found here, considerably differ from those values obtained with the conventional gammacoefficients suggested in the literature.