Oceanic dipoles in a surface quasigeostrophic model

TL;DR

This paper introduces a new explicit linear eigenvalue solution for surface quasigeostrophic equations, explaining mesoscale ocean dipoles and their vertical exchanges observed in satellite data.

Contribution

It provides a novel analytical solution for multipoles in surface quasigeostrophic models, linking observed ocean dipoles to mass conservation and vertical exchange mechanisms.

Findings

Explicit eigenvalue solution for multipoles

Model reproduces observed dipole structures

Mass conservation explains frontogenetic velocities

Abstract

Analysis of satellite altimetry and Argo float data leads Ni et al. (2020, JGR Oceans) to argue that mesoscale dipoles are widespread features of the global ocean having a relatively uniform three-dimensional structure that can lead to strong vertical exchanges. Almost all the features of the composite dipole they construct can be derived from a model for multipoles in the surface quasigeostrophic equations for which we present a straightforward novel solution in terms of an explicit linear eigenvalue problem, allowing simple evaluation of the higher radial modes that appear to be present in the observations and suggesting that mass conservation may explain the observed frontogenetic velocities.