January 2010 – December 2011
We propose to investigate eddy-wind-topography interaction dynamics through a series of carefully designed model sensitivity experiments. Early studies have focused on either eddy-wind or eddy-topography interaction. The question on how the eddy interacts with both wind and topography when they are concurrently present (i.e., in the coastal ocean) is largely unexplored. The project will take the approach of investigating eddy-wind-topography interactions through a set of idealized numerical experiments using the Hybrid Coordinate Ocean Model (HYCOM). In each case, an isolated warm core eddy will be embedded in the HYCOM. We will vary surface wind fields in terms of wind speed and direction. In each wind forcing scenario, HYCOM will simulate responses of an eddy moving in three different topographic settings, from a flat bottom, to a generic shelf-slope, then to the realistic Gulf of Mexico topography.
We will track the simulated eddy using T/S and passive tracer fields. Three-dimensional velocity fields within and adjacent to the eddy, along with eddy propagation and dissipation properties, will be examined and compared. Non-dimensional numbers including Ekman number, eddy intensity number, topographic and planetary beta effect numbers, and eddy barotropy number will be used to record the temporal variations of eddy intensity and propagation in the parameter space. The processes associated with eddy property modifications (e.g., eddy collision, generations of the slope cyclones and vortex filaments) by topographic effect and linear/nonlinear wind-induced Ekman dynamics will be partitioned. This research is expected to improve the fundamental understandings of eddy evolutions in the presence of both surface wind forcing and bottom topographic forcing.