  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.
