Abstract

Building on recent theoretical advances (i.e. Petrelis et al., J. Phys. Oceanogr., 36, 1053—1071, 2006), we analyze the low-mode structure of internal tides generated in laboratory experiments by a two-dimensional ridge in a channel of finite depth. The height of the ridge is approximately half of the channel depth and the regimes considered span sub- to supercritical topography. When the tidal excursion is small, of the order of 1% of the topographic width, our results agree well with linear theory. For this topographic configuration, and consistent, for example, with the predictions of complementary Regional Ocean Modeling System (ROMS) numerical simulations (di Lorenzo et al., J. Phys. Oceanogr., 36, 1072—1084, 2006), most of the linear baroclinic energy flux is associated with the mode 1 tide.

For reasons to be discussed, the interpretation of experimental data is notably more involved when internal waves of various frequencies are present, as is the case with real tides, which represent a superposition of various diurnal (K1, O1) and semidiurnal (M2, S2) components. This in turn complicates the modal analysis when a continuum of frequencies are present e.g. due to internal wave forcing by a gravity current.

This work was jointly conducted with Paula Echeverri (MIT), Tom Peacock (MIT) and Kraig Winters (UCSD-SIO) with additional contributions by Neil Balmforth (UBC) and Alexis Kaminski (U. Alberta).

Morris R. Flynn completed a Ph.D. under the supervision of Drs. Colm P. Caulfield and Paul F. Linden at the Univ. of California—San Diego in 2006 and subsequently worked as an instructor/researcher at the Massachusetts Inst. of Technology in 2007 and 2008. Morris’s research interests include environmental and biological fluid mechanics, the natural ventilation of buildings and the continuum modeling of traffic flow.