Alternative Interpretations for Microstructure Patches in the Thermocline

Abstract

Dep. Applied Mechanics Univ. California at San Diego, La Jolla, CA 92093, USA J (Journal-Article) M (Marine) Two interpretations of microstructure patches measured in the main thermocline of the North Pacific by Gregg (1980) are questioned. He concludes that the observed microstructure is not fossil-temperature turbulence and that the observed Cox numbers imply vertical diffusivities by turbulent mixing which are about 10 super(-2) times smaller than canonical values of order 10 super(-4) m super(2) s super(-1). The first conclusion that the microstruture is not fossil depends on an unnecessary assumption that in order to be fossil the microstructure must not be moving: actually, fossil-turbulence microstructure must always have internal wave and laminar restratification motions. The second conclusion depends on the first. The pattern of Thorpe-displacement scales for the patches containing zero temperature gradients implies they wer...