SEMINAR: OI Seminar Series - Luc Rainville

Title:Observations of Internal Waves from Autonomous Gliders - studies from Luzon Strait and from Tasmania.

Abstract: The vertical isopycnal displacements associated with internal waves are estimated using autonomous underwater gliders. Although they travel relatively slowly, the spatial coverage and persistence of gliders make them a fantastic tool to study complex internal wave fields. Near Taiwan, over 15,000 profiles from Seagliders and Spray gliders collected during 19 different missions since 2007 provide a unique set of measurements to estimate the amplitude and phase of the linear semidiurnal and diurnal internal waves in this energetic region, particularly in the previously poorly sampled area near the eastern ridge and the Pacific side of Luzon Strait. The mean and variability of the internal wave field from gliders are described. In addition to tracking individual isopycnals, the gliders can also be used to map the mode-1 semidiurnal and diurnal internal wave field, resulting in a complete map of baroclinic energy flux over a roughly 600 by 800-km region estimated strictly from observations. The same technique is applied to the Seaglider data from the missions conducted by UWA off the east coast of Tasmania. As an important motivation for upcoming observational program T-TIDE, the glider data capture the incoming mode-1 internal tide directed towards the steep continental slope. T-TIDE aims to find out what happens to this large energy flux.