Evidence of a forward energy cascade and Kolmogorov self-similarity in submesoscale ocean surface drifter observations

Andrew C. Poje, Tamay M Ozgokmen, Darek J. Bogucki, A. D. Kirwan

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Abstract

rom the near-simultaneous release of O(100) GPS-tracked surface drifters in the northern Gulf of Mexico, we examine the applicability of classical turbulent scaling laws to upper ocean velocity fields. The dataset allows direct estimates of both velocity structure functions and the temporal evolution of the distribution of particle pair separations. On 100 m-10 km spatial scales, and time scales of order 1-10 days, all metrics of the observed surface fluctuations are consistent with standard Kolmogorov turbulence theory in an energy cascade inertial-range regime. The sign of the third-order structure function is negative and proportional to the separation distance for scales .10 km where local, fluctuating Rossby numbers are found to be larger than 0.1. The scale-independent energy dissipation rate, or downscale spectral flux, estimated from Kolmogorov's 4/5th law in this regime closely matches nearby microscale dissipation measurements in the near-surface. In contrast, similar statistics derived from a like-sized set of synthetic drifters advected by purely geostrophic altimetricAVISO data agree well withKolmogorov-Kraichnan scaling for 2D turbulence in the forward enstrophy cascade range. Published by AIP Publishing.

Original languageEnglish (US)
Article number020701
JournalPhysics of Fluids
Volume29
Issue number2
DOIs
StatePublished - Feb 1 2017

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ASJC Scopus subject areas

  • Condensed Matter Physics

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