An aircraft study of turbulence dissipation rate and temperature structure function in the unstable marine atmospheric boundary layer

Abstract

The dissipation rate of turbulent kinetic energy, e, and the temperature structure function parameter, C T 2, have been measured over water from the near surface (Z = 3 m) to the top of the boundary layer. The near surface values of e and C T 2 were used to calculate the velocity and temperature Monin-Obukhov scaling parameters u * and T *. The data collected during unstable lapse rates were used to evaluate the feasibility of extrapolating the values of e and C T 2 as a function of height with empirical scaling formulae. The dissipation rate scaling formula of Wyngaard et al. (l971 a) gave a good fit to an average of the e data for Z < 0.8 Z i. In the surface layer the scaling formula of Wyngaard et al. (1971b) disagreed with the C T 2 values by as much as 50%. This disagreement is due to an unexpected reduction in the measured values of C T 2 forZ < 30 m. At this point it is not clear if the discrepancy is a unique property of the marine boundary layer or if it is simply some unknown instrumental or analytical problem. The mixed layer scaling results were similar to the overland results of Kaimal et al. (1976).