TY - JOUR

T1 - Correcting surface wave bias in structure function estimates of turbulent kinetic energy dissipation rate

AU - Scannell, Brian

AU - Rippeth, Thomas

AU - Simpson, John

AU - Polton, Jeff

AU - Hopkins, Jo

N1 - Brian Scannell is an ENVISION DTP PhD student

PY - 2017/10

Y1 - 2017/10

N2 - The combination of acoustic Doppler current profilers and the structurefunction methodology provide an attractive approach to making extended timeseries measurements of oceanic turbulence (the rate of turbulent kinetic energydissipation, e) from moorings. However, we show that for deploymentsin the upper part of the water column, estimates of e will be biased by thevertical gradient in wave orbital velocities. To remove this bias, we develop amodified structure function methodology, which exploits the differing lengthscale dependencies of the contributions to the structure function due to turbulent and wave orbital motions. The success of the modified method is demonstrated through comparison of e estimates based on data from instruments at three depths over a three month period under a wide range of conditions, with appropriate scalings for wind stress and convective forcing.

AB - The combination of acoustic Doppler current profilers and the structurefunction methodology provide an attractive approach to making extended timeseries measurements of oceanic turbulence (the rate of turbulent kinetic energydissipation, e) from moorings. However, we show that for deploymentsin the upper part of the water column, estimates of e will be biased by thevertical gradient in wave orbital velocities. To remove this bias, we develop amodified structure function methodology, which exploits the differing lengthscale dependencies of the contributions to the structure function due to turbulent and wave orbital motions. The success of the modified method is demonstrated through comparison of e estimates based on data from instruments at three depths over a three month period under a wide range of conditions, with appropriate scalings for wind stress and convective forcing.

KW - OCEANOGRAPHY

U2 - 10.1175/JTECH-D-17-0059.1

DO - 10.1175/JTECH-D-17-0059.1

M3 - Article

VL - 34

SP - 2257

EP - 2273

JO - Journal of Atmospheric and Oceanic Technology

JF - Journal of Atmospheric and Oceanic Technology

SN - 0739-0572

IS - 10

ER -