Abstract
Internal Solitary Waves (ISWs) in the ocean mainly arise from the interaction between a mean flow (e.g. a barotropic tidal flow) and the coastal topography. In the Bay of Biscay however, ISWs have been detected far from the coasts, at distance large enough for the latter process to be unlikely responsible for their generation. It has rather been suggested that, at these locations, the ISWs could result from the interaction of the internal gravity wave field forced by the tide - the so-called internal tide - with the thermocline (New & Pingree 1990, 1992, Pingree & New, 1991). Theoretical works have been achieved by Gerkema (2001) and Mauge & Gerkema (2007) (using a modal approach) and by Akylas et al. (2007), which demonstrate the feasibility of such a conjecture. To our knowledge however, the generation of ISWs by the internal tide has never been observed directly nor simulated numerically. This is the purpose of the our work.
We will present preliminary results of the generation of ISWs at an oceanic thermocline hit by an internal tide field, using two-dimensional direct numerical simulations; an idealized non-rotating situation will be considered. The generation conditions of the ISWs field will be analyzed, using a modal analysis. Extrapolation to the oceanic case will eventually be discussed.