Analysis of Velocity Measurements at NOTS Pier on San Clemente Island
Abstract
This report describes oceanographic observations at NOTS Pier on San Clemente Island, CA. Velocity measurements were made to assess the suitability of NOTS Pier for testing ocean turbulence sensors. Measurements at NOTS Pier on San Clemente Island off the coast of Southern California show that the water velocities there consist of tidal currents and oscillations caused by surface waves. Tidal currents are parallel to the shoreline with frequencies that are mixed diurnal and semidiurnal with an rms amplitude of approximately 8 cm/s. Ocean swells (10- to 12-s period) and wind waves (3- to 5-s period) induce periodic horizontal and vertical velocities with rms amplitudes of 5 cm/s and 1 cm/s, respectively, under quiet conditions. Direct measurement of small-scale velocities with high-frequency current meters indicates that the velocity field under the pier is consistent with anisotropic turbulence. Using a model of "frozen field" turbulence in an oscillating mean flow, estimates of the turbulent dissipation rate are Ew = 1.1 x 10(expn -5)m2/s3 based on the horizontal velocity spectrum and Ew = 1.1 x 10(expn -6)m2/s3 for the vertical.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 30, 1999
- Accession Number
- ADA639231
Entities
People
- Peter J. Hendricks
Organizations
- Naval Undersea Warfare Center