Office of Naval Research

Data Assimilation and Diagnostics of Inner Shelf Dynamics

Arthur J. Miller

Award: $105,000
Duration: 2014-2015

Collaborators: Emanuele Di Lorenzo (Georgia Tech) and Kevin Haas (Georgia Tech)

Project Summary.
We propose to use the Regional Ocean Modeling System (ROMS), including a surface wave model, to simulate the processes that control stratification and currents in a theoretical inner shelf region that roughly corresponds to the Point Sal beach off the coast of Point Conception, which is likely to be the site of the DRI. We will first build the model grids, which will nest from regional (10km) to local (3km) to inner-shelf (1km-->200m) to surf zone (20m) resolutions. The vertical resolution will be 1m in the upper ocean to account for diurnal mixed layer changes and rip current structures. The topography will be a simple smoothed representation of an upwelling shelf, with a specified topographic bump to break symmetries and induce inhomogeneities. The domain will be periodic north-south for the outer most model grid (e.g. 10km grid) and open-boundary to the west.
We will initially focus on forward modeling, spinning up the flows in the domain and testing for stability of the integration schemes. After the model flows are shown to exhibit realistic behavior in terms of eddy structures on the shelf, rip currents across the surf zone, longshore flows, etc., we will test sensitivities of the inner shelf circulation and stratification to various forcing functions associated with the September-October-November seasonal time frame. This will include: Diurnal heating versus steady heating by solar radiation; Wind direction changes, boundary current inflows and outflows, internal wave generation at the shelf break, and incoming swell from the SW.
Our analysis of these forward runs will be to characterize the vertical structure of the temperature and currents on the inner shelf in terms of it mean state and intermittency, especially as it may affect density and acoustic propagation.