Dynamical mode analysis of tidal flows through the Strait of Gibraltar
Sathsara Dias, Sudam Surasinghe, Kanaththa Priyankara, Marko Budišić and Erik Bollt
Dynamics Days 2020 An international conference on chaos and nonlinear dynamics, Hilton, Hartford CT, USA, January 2020
Recent advances in dynamical systems made it possible to analyze complex systems in data-driven, equation free methods. In particular, our work uses the Dynamic Mode Decomposition (DMD), a numerical method based on the linear Koopman operator that identifies spatial and temporal patterns (modes) from simulated or measured snapshots of nonlinear dynamics. As DMD is equation-free, it can analyze nonlinear models from physical sciences, engineering, videography, economics, etc. We applied DMD to identify flow constituents in a three-dimensional simulation of tidal flows through the Strait of Gibraltar over a six-day period. DMD managed to isolate well-known tidal patterns, such as the Western Alboran Gyre, the twelve-hour lunar tide cycle (M2), and the tidal bore discharging Atlantic waters into the Mediterranean. Additionally, the DMD modes were able to clarify the structure of a recurrent flow pattern occurring as the water passes the Camarinal Sill just to the Atlantic side of Gibraltar.