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Title: Spectral and bulk properties of turbulence in the surface layer of air over the sea
Author: Garratt, John Roy
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1970
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An analysis has been made of the vertical profiles of mean wind speed u, potential temperature 6 and specific humidity q in the first 16 m. above a sea surface, and of the eddy fluxes of heat and momentum, velocity and temperature spectra, flux cospectra and other statistics using simultaneous observations of fluctuations of air temperature, vertical and horizontal (longitudinal) wind speed at any two of the levels 1.5 m., 4 m., and 12 m. Profiles of u and θ are found to be dissimilar in non-neutral stability implying a variation of the eddy transfer coefficient ratio KH/KM agreeing, qualitatively, with the direct flux-gradient measurements. The ratio is significantly greater than unity in unstable, and less than unity in stable, stratification. For the majority of runs fluxes of heat and momentum are approximately constant with height, the remainder having a variation implying significant horizontal gradients of wind speed and temperature. Further only when the momentum flux is approximately constant with height is there close agreement with the friction velocity evaluated independently from the wind profile. An empirical formula is suggested relating heat flux to the more readily measured quantities u10' θ10-θ. The spectra at high frequencies are related to the Kolmogorov predictions and the Universal constants are evaluated for the velocity spectrum and structure function. Evaluation of a non-dimensional dissipation rate as a function of Ri is shown to be consistent with a Von Karmen constant of 0.4.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available