Oceanic Energy Cascade from Global to Regional Predictive Models
Lead PI: Bruce Cornuelle, Scripps Institution of Oceanography
Start Year: 2015 | Duration: 3 Years
Partners: University of Hawaii, Naval Research Laboratory – Stennis Space Center & Massachusetts Institute of Technology
Understanding the cascade of energy injected into the ocean is crucial to developing our knowledge of ocean predictability and dynamics. Steep ridges, islands, and atolls in the ocean scatter waves and convert energy at a variety of scales, from long Rossby waves through mesoscale, sub-mesoscale, and internal waves. This energy injected at the steep ridges has significant implications for global and regional ocean prediction. Models with insufficient resolution, or which lack the physics of the energy cascade will miss the topographic effects and suffer a drop in predictive skill. These localized effects may play an important role in the basin-wide circulation that is currently predicted by the Navy’s global HYCOM/NCODA system.
The ONR-funded FLow Encountering Abrupt Topography (FLEAT) project aims to understand how the ocean is altered by steep ridges and islands at the full range of length scales in the western tropical Pacific region encompassing Palau and Guam. In cooperation with this project, we will use models to examine how the cascade of energy and enstrophy due to topography impact global and regional predictive skill in the FLEAT region, with a focus on the Navy HYCOM model. We will use a state-of-the-art numerical model and advanced state estimation techniques to reproduce the flows in the FLEAT region by fitting the ocean circulation models to observations. Our goal is to examine the effects of local energy conversion at and near ridges, how the enstrophy affects local ridge processes, and how the energy cascade affects lower wavenumbers away from the ridge in the open ocean.