On the interactions between planetary geostrophy and mesoscale eddies in the oceans

We use multiple-scales asymptotics to investigate the interactions between large-scale planetary-geostrophic dynamics and mesoscale quasigeostrophic eddies in the oceans. We revisit and amplify the original analysis of Pedlosky (Pedlosky, J., 1984. Journal of Physical Oceanography 14, 448-455.). This original analysis did not include a mechanism for eddies to feed back onto the large-scale dynamics; in the new analysis we show how such a connection is possible. In particular, we show that two-way coupling between the large- and meso-scale dynamics occurs whenever the large-scale flow is anisotropic, for example in western boundary currents and the Antarctic circumpolar current. We also present results from simulations of the large-scale equations including eddy effects with simple geometry and forcing.