Statistics of Mixing Parameters in the Upper Ocean During JASIN Phase 2

Abstract

Turbulence levels obtained during the 1978 Joint Air-Sea Interaction experiment (JASIN) have been examined from measurements of both temperature gradient and velocity shear. These measurements, obtained with the vertical profiler OCTUPROBE 2, have been analyzed to compute viscous dissipation rule, ?, and dissipation of temperature variance, ?τ. As in a previous study, the dissipation rate increased as the surface energy input parameterized by U103 increased. The JASIN study indicated only one-third of the viscous dissipation rate observed in a similar experiment in a region on the Scotian shelf and this difference is discussed. A mixing parameter, Γ, related the flux Richardson number has been estimated from simultaneous measurements of ? and ?τ. The mean value of Γ corresponds to a flux Richardson number of 0.21. Heat flux estimates from temperature microstructure measurements were fund to be consistent with other results of the JASIN experiment. The statistical distributions of dissipation, ?, mixing parameter, Γ, and other quantities were found to be consistent with lognormality. This result has been used to estimate error limits of mean quantities which may be used as parameters in mixed layer models.