Abstract
Ocean eddies play an important role in the distribution of heat, salt,
and other tracers in the global ocean. But while surface eddies have
been studied extensively, deeper eddies are less well understood. Here
we study deep coherent vortices (DCVs) in the Northeast Atlantic Ocean
using a high resolution numerical simulation. We perform a census of the
DCVs on the $27.60$ kg/m$^3$ isopycnal, at the depth of
$700-1500$ m, where DCVs of Mediterranean water (meddies) propagate.
We detect a large number of DCVs, with maxima around continental
shelves, and islands, dominated by small and short-lived cyclones.
However, the large and long-lived DCVs are mostly anticyclonic. Among
the long-lived DCVs, anticyclonic meddies, stand out. They grow in size
by merging with other anticyclonic meddies. Cyclonic meddies are also
regularly formed, but most of them are destroyed near their formation
sites due to the presence of the energetic anticyclonic meddies, which
destroy cyclones by straining and wrapping the positive vorticity around
their core. During their life cycle, as they propagate to the southwest,
anticyclonic meddies can interact with other DCVs, including
anticyclones containing Antarctic Intermediate Water generated near the
Moroccan coast, Canary anticyclonic DCVs and cyclonic DCVs generated
south of $30^\circ$N along the African continental
shelf. With these latter, they can form dipoles, and with the former,
they co-rotate pro tempore. Thus, a more detailed view of the life cycle
of anticyclonic meddies is proposed: they grow by merging, undergo
multiple interactions along their path, and they decay at low latitudes.