%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Cuypers, Y.
%A Bouruet-Aubertot, P.
%A Vialard, Jérôme
%A McPhaden, M. J.
%T Focusing of internal tides by near-inertial waves
%D 2017
%L fdi:010069421
%G ENG
%J Geophysical Research Letters
%@ 0094-8276
%K OCEAN INDIEN ; ZONE TROPICALE
%M ISI:000398183700040
%N 5
%P 2398-2406
%R 10.1002/2017gl072625
%U https://www.documentation.ird.fr/hor/fdi:010069421
%> https://www.documentation.ird.fr/intranet/publi/2017/04/010069421.pdf
%V 44
%W Horizon (IRD)
%X The refraction of internal waves by lower-frequency near-inertial waves has been predicted theoretically, but never observed before. Here, we report observations of semi-diurnal internal tides generated by the rough topography of the Central Indian Ridge, in the presence of a strong, lower-frequency near-inertial wave field generated by a tropical storm. The semi-diurnal internal tide energy is trapped within upward propagating bands with a periodicity close to the inertial period. A ray-tracing model suggests that this trapping results from the internal tide refraction by the shear associated with near-inertial waves. This yields a strong increase of the internal tide energy and shear in space-time regions where the background flow focuses the rays, leading to the formation of caustics. This mechanism may increase vertical mixing generated by baroclinic tides in the vicinity of mid-ocean ridges in tropical regions.
%$ 032