SLS – Joe Lacasce (University of Oslo)

The vertical structure of ocean eddies

Since we began observing the ocean surface with satellites,
it’s been of interest to understand how the surface fields reflect motion
at depth. A series of recent modeling studies suggest the vertical structure
is fairly well-captured by a single mode, intensified near the surface and
decaying to zero with depth. A study of 69 globally-distributed current
meters supports this, in many locations outside of the tropics. The reason
for the dominance of a surface is explored theoretically, using a simple
two layer model. The latter predicts a wavenumber frequency spectra
which resembles that in the ocean, except at small scales. The latter are
shown to be more likely to transfer energy to large scales, leaving the
(non-dispersive) large scale waves in tact. A similar conclusion was made
previously from idealized numerical experiments.