Atmosphere Ocean Science Colloquium
Progress in Studying Ocean Turbulence from Lagrangian Trajectories
Speaker: Jonathan Lilly, NWRA
Location: Warren Weaver Hall 1302
Date: Wednesday, April 4, 2018, 3:30 p.m.
Trajectories from freely-drifting, or "Lagrangian", instruments represent one of the primary windows into the turbulent ocean circulation. Here two new methods for extracting information from this type of data. Firstly, it is shown that the time-varying properties of coherent vortices or eddies can be accurately estimated from the trajectories of trapped particles. This is done using a time-frequency optimization method termed "wavelet ridge analysis" which has a deep connection to the underlying physics. Secondly, the main properties of the disorganized turbulent background, in between the eddies, can be well captured with a very simple stochastic model, a damped version of fractional Brownian motion. The theory of these two analysis methods are presented together with preliminary global results. These series analysis tools are of general applicability and therefore relevant to problem areas outside of oceanography.