Universal structure of mesoscale eddies in the ocean

Abstract

Mesoscale eddies dominate oceanic kinetic energy at sub-inertial frequencies. Their three-dimensional structure has, however, remained obscure, hindering better understanding of eddy dynamics. Here by applying the composite analysis of satellite altimetry and Argo float data to the globe, we show that despite remarkable regional differences in amplitude, extent and polarity, etc., mesoscale eddies have a universal structure in normalized stretched coordinates. Horizontally, the associated pressure anomaly is well described by a function of the normalized radial distance from the eddy center R(rn)=(1−rn2/2)• exp(−rn2/2), whereas vertically it is sinusoidal in a stretched coordinate zs = ƒ z0 (N/f )dz, where N and f are the buoyancy frequency and the Coriolis parameter.