Currently Funded Research Projects

Toward a global 1/25 degree HYCOM ocean prediction system with tides
Co-PI with Eric Chassignet (lead PI) on five-year award for $2,156,665 from Office of Naval Research, starting January 28, 2009. Other collaborators: Harley Hurlburt, Joseph Metzger, and Alan Wallcraft of Naval Research Laboratory. In recent years, increases in computer power have allowed both baroclinic tides and mesoscale eddies to be resolved on a global scale. In this project, we will simultaneously resolve both baroclinic tides and an eddying general circulation in a 32-layer, 1/25 degree simulation of HYCOM, the HYbrid Coordinate Ocean Model. A preliminary 1/12.5 degree simulation has been run for 5 years and we have just begun to analyze it. Among other things, we will study the impact of explicitly resolved tides on the general circulation, and the impact of the general circulation and associated mesoscale eddies and horizontally varying stratification on baroclinic tides..

Effects of small-scale bathymetric roughness on the global internal wave field
Co-PI with John Goff (U-Texas) on three-year award for $244,017 from Office of Naval Research, starting March 23, 2007. Other collaborators: Patrick Timko, Walter Smith, Karen Marks. This project is a collaboration between marine geophysicists and physical oceanographers. The internal wave field, which is responsible for much of the mixing that occurs in the ocean, is generated in part by tidal and geostrophic flows over rough topography. Horizontal scales as small as a few kilometers are important in this wave generation process, yet are not resolved in global topographic datasets. Here we take advantage of the knowledge geophysicists have of the seafloor, to generate a synthetic bottom roughness which is correct in a statistical sense, and which contains adequate variance at small horizontal scales. We will test whether this augmented roughness increases the internal wave generation in global models.

Collaborative Research: Understanding tidal resonances in the present-day and ice-age oceans
Co-PI with Samar Khatiwala of Lamont-Doherty Earth Observatory (Columbia University) on three-year award for $410,907 (UT part $210,475) from National Science Foundation, starting October 1, 2006. Other collaborators: Patrick Cummins, Chris Garrett, Richard Karsten, Pierre St-Laurent, Graig Sutherland, Doug MacAyeal, Glenn Milne, Jerry Mitrovica. In this project we have used both analytical and numerical models to understand how factors such as the wavelength and frequency of the tidal astronomical forcing, and the depths and length scales of the open and coastal oceans, affect tidal resonance. Of particular interest is the coupling between shelf and open-ocean tides. We find in both our analytical and numerical models that removal of relatively small shelf regions can have a substantial and far-reaching effect on the open-ocean tide. This is relevant for understanding how the tides are impacted by changes in sea level. For instance, during the ice ages, sea level was much lower, and the area of continental shelves was consequently much reduced. We have found that the modeled tides during the ice age were quite different from what they are today. In particular, the tides in the ice-age Labrador Sea were much larger. This in turn has consequences for understanding Heinrich events, the large iceberg discharges that took place during the ice ages. Heinrich events originated primarily in the Labrador Sea, and we have hypothesized that the large modeled tides in the Labrador Sea may have played a role in the dynamics of these events. The hypothesis is motivated in part by the very substantial impacts of tides on ice streams and floating ice shelves that have been observed in present-day Antarctica.

Embedding a forward model of barotropic and baroclinic tides into a high-resolution general circulation model
Sole PI on five-year contract which ultimately delivered $191,771 from Naval Research Laboratory, starting September 1, 2006. Collaborators: Harley Hurlburt, Joseph Metzger, and Alan Wallcraft of Naval Research Laboratory, Patrick Timko and Eric Chassignet of Florida State University. This contract provided the support necessary to implement and test tides in HYCOM, thus laying the groundwork for a large part of the HYCOM follow-on proposal described above. This contract was superceded once the HYCOM follow-on grant was obtained.