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Walter Craig: Surface signatures of internal waves

Submitted by Andreas Freund on January 27, 2016 - 11:00am

Speaker: Walter Craig, McMaster University

Date: January 27, 2016

Title: Surface signatures of internal waves

Abstract: Internal waves occur in fluid bodies that are stratified by density, such as a warm layer lying over colder layers in a tropical ocean, or a fresh water layer over a salt water layer in a fjord. Often these layers are very well delineated, separated by a sharp thermocline, respectively a pycnocline, in which internal waves may propagate. The surface manifestation of an internal wave often includes a narrow zone of rough water, a `rip’, followed by an extremely calm sea state, the `mill pond effect’. In work with Ph. Guyenne and C. Sulem, we re-examine the analysis of this signature of the presence of an internal soliton. Our analysis describes the resonant coupling of the internal and surface modes, and the resulting characteristic tightly-localized rip region on the surface. It turns out that this phenomenon has a close analogy with quantum radiative absorption and scattering, in the semiclassical limit.