Estimates of the turbulent kinetic energy (TKE) balance in shelf seas

Abstract

Turbulence is a difficult quantity to measure and to model in the coastal environment, however it is one of the most important as it controls the vertical flux of materials, such as nutrients, sediment and plankton. Developments in measurement techniques, particularly in acoustic instrumentation, have improved the measurements of production and dissipation of turbulent kinetic energy (TKE). Estimates of turbulence production using Acoustic Doppler Current Profilers, ADCPs, have become common and almost routine, and more recently the structure function technique (Wiles et al., 2006) has allowed us to produce estimates of turbulence dissipation. In addition Acoustic Doppler Velocimeters, ADVs, have become the standard instruments to measure turbulence, using direct estimates of the Reynolds stresses and spectral methods for the turbulence dissipation. The aim of this work will be to look at validating the structure function method against ADV data and then to combine ADVs, ADCPs and Pulse Coherent Acoustic Doppler Profilers, PC-ADPs, to look at the TKE balance throughout the water column. The data involved in this study, which was from Liverpool Bay, showed some differences between the turbulent production measured by an ADCP and the turbulent dissipation measured by an ADV. This paper discusses possible reasons for these differences, and the approaches used to try to correct for them