Statistics of Shear and Turbulent Dissipation Profiles in Random Internal Wave Fields,
Abstract
Because breaking internal waves produces most of the turbulence in the thermocline, the statistics of Epsilon, the rate of turbulent dissipation, cannot be understood apart from the statistics of internal wave shear. The statistics of Epsilon and shear are compared for two sets of profiles from the northeast Pacific. One set, PATCHEX, has internal wave shear close to the Garrett and Munk model, but the other set, PATCHEX north, has average 10-m shear squared, (S(2)10), about four times larger than the model. The 10-m shear components, S sub x, and S sub y, were measured between 1 and 9 MPa and referenced to a common stratification by WKB scaling. The scaled components, S sub x, and S sub y, are found to be independent and normally distributed with zero means, as assumed by Garrett and Munk. This readily leads to analytic forms for the probability densities of S(2)10 and S(4)10. The observed probability densities of S(2)10 and S(4)10 are close to the predicted forms, and both are strongly skewed. The probability density of the inverse Richardson number, Ri sub 10 =S(2)10/(N2), is a scaled version of the probability density of S(2)10. The PATCHEX distribution cuts off near Ri sub 10 = 4, as found by Eriksen, but the PATCHEX north distribution extends to higher values, as predicted analytically.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1993
- Accession Number
- ADA269681
Entities
People
- D. B. Percival
- H. E. Seim
- M. C. Gregg
Organizations
- University of Washington