Microstructure Measurements from a Towed Undulating Platform

Abstract

MicroSoar, an undulating profiler capable of measuring turbulence parameters such as Thorpe scales and thermal dissipation rate while being towed at speeds of up to 4 m s?1, offers the possibility of obtaining a close-to-synoptic image of mixing over large spatial areas. In this paper, the method of calculating Thorpe scales from the high-frequency MicroSoar data is developed, and results from data taken off the coast of Oregon during the summer of 2001 are presented. Large Thorpe scales and elevated measurements of the thermal dissipation rate are shown to be associated with shear at the edge of the coastal jet. It is further shown that using MicroSoar data rather than Sea-Bird conductivity?temperature?depth data extends the range of measurable overturns to smaller scales, particularly in regions of low stratification.