Atmosphere Ocean Science Colloquium

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The Vertical Structure of Ocean Eddies

Speaker: Joe Lacasce, University of Oslo

Location: Warren Weaver Hall 1302

Date: Wednesday, March 29, 2017, 3:30 p.m.

Synopsis:

Since we began observing the ocean surface with satellites, it's been of interest to understand how the surface fields reflect the motion at depth. Recent modeling studies suggest the vertical structure is well-captured by a single modal structure, intensified at the surface and decaying to zero with depth. The results from a study of 69 globally-distributed current meters support this, in many locations outside of the tropics. The reason for this is explored theoretically. The solution of the baroclinic mode problem shows that surface-intensified solutions obtain with only modest bottom slopes and/or bottom friction. Furthermore, theoretical wavenumber-frequency spectra, based on a two layer model, resemble those obtained with sea surface height data, except at small scales. The small scale waves are shown to be unstable, thereby transferring energy to larger waves. The results then suggest the observed spectra likely reflect surface Rossby waves, with scales greater than the deformation radius.