loading page

Scaling of moored surface ocean turbulence measurements in the Southeast Pacific Ocean
  • +2
  • Una Kim Miller,
  • Christopher J Zappa,
  • Seth F Zippel,
  • John Thomas Farrar,
  • Robert A. Weller
Una Kim Miller
Lamont-Doherty Earth Observatory of Columbia University

Corresponding Author:[email protected]

Author Profile
Christopher J Zappa
Lamont-Doherty Earth Observatory of Columbia University
Author Profile
Seth F Zippel
Woods Hole Oceanographic Institution
Author Profile
John Thomas Farrar
Woods Hole Oceanographic Institution
Author Profile
Robert A. Weller
Woods Hole Oceanographic Institution
Author Profile

Abstract

Estimates of turbulence kinetic energy (TKE) dissipation rate (ε) are key to understanding how heat, gas, and other climate-relevant properties are transferred across the air-sea interface and mixed within the ocean. A relatively new method involving moored pulse-coherent Acoustic Doppler Current Profilers (ADCPs) allows for estimates of ε with concurrent surface flux and wave measurements across an extensive length of time and range of conditions. Here, we present 9 months of moored estimates of ε at a fixed depth of 8.4m at the Stratus mooring site (20°S, 85°W). We find that shear- and buoyancy-dominant turbulence regimes are defined equally well using the Obukhov length scale ( LM ) and the newer Langmuir stability length scale (LL ), suggesting that ocean-side friction velocity (u*) implicitly captures the influence of Langmuir circulation at this site. This is illustrated by a strong linear dependence between surface Stokes drift (us) and and is likely facilitated by the steady Southeast trade winds regime. The traditional Law of the Wall (LOW) and surface buoyancy flux scalings of Monin-Obukhov similarity theory scale our estimates of well, collapsing data points near unity. We find that the newer Stokes drift scaling ( usu*2 /mixed layer depth) scales ε well at times but is overall less consistent than LOW. Scaling relationships from prior studies in a variety of aquatic and atmospheric settings largely agree with our data in destabilizing, shear-dominant conditions but diverge in other regimes.