Abstract: Generation of solitary waves by an internal-wave beam impinging on the pycnocline.



Authors: Theo Gerkema

T. Gerkema (1), L. Gostiaux (2), M. Mathur (3), M. Mercier (4), N. Grisouard (5), J. Magelhãen (6), T. Dauxois (4), J.C.B. Da Silva (6), C. Staquet (5).

Observations in the Bay of Biscay have shown that an internal tide beam can generate solitons as it impinges on the seasonal thermocline. To study this process in a laboratory setting, we have carried out experiments on the (rotating) platform in Grenoble.
We used a wavemaker to create a well-defined internal-wave beam directed upward, towards the pycnocline. Measurements show that the beam widens and loses part of its energy as it traverses the pycnocline. Meanwhile, internal waves are generated that are partly trapped in the pycnocline; under the right conditions, they take the form of solitary waves. Here we will show the first results of these experiments, as well as a comparison with a numerical model used to simulate the experiments.

(1) Royal NIOZ, Texel, Netherlands.
(2) Coriolis-LEGI, Grenoble, France.
(3) Dept. Mech. Eng, MIT, US.
(4) Lab. de Physique, ENS, Lyon, France.
(5) LEGI, Grenoble, France.
(6) Inst.de Oceanografia, FCUL, Lisboa, Portugal.