Estimating boundary layer fluxes from shipboard measurements of dissipations of turbulent kinetic energy and temperature variance

Abstract

Velocity and temperature fluctuation measurements were made over the open ocean from instruments mounted on the R/V ACANIA. These data were examined to determine the validity of present formulations and prediction techniques. Values of momentum flux, u* 2, were inferred from the rate of dissipation of turbulent kinetic energy, E. Dissipation values were obtained from spectral estimates and inner scale estimates. Values of u* were examined for representativeness on the basis of the constant-flux assumption and by comparisons with other studies. The vertical variation of the dissipation rate was examined for possible effects of stability and wind-wav e coupling. The momentum flux, computed from spectra, supported the constant-flux assumption for neutral conditions. For periods of instability, the stability corrections applied to the vertical variation of E resulted in the proper adjustments toward the predicted slope. The reductions in momentum transfer during periods of stable stratifications were consistent with wind-wave coupling effects described by Davidson. The shape of a spectrum of temperature fluctuations was in agreement with predictions.