[SLS Pre-Defense] Weiguang (Roger) Wu

“Precession of Ocean Eddies as Vortex Rossby Waves”

Vortex Rossby waves (VRWs) were first introduced in meteorology to explain the spiral rainbands of tropical cyclones. Unlike planetary Rossby waves, which arise from the meridional gradient of planetary potential vorticity, VRWs are supported by the radial vorticity gradient within a vortex. In hurricanes, the vertical motions associated with VRWs form the spiral cloud bands seen in satellite and radar imagery. In the ocean, however, VRWs are difficult to detect with current satellite observations, which can only marginally resolve mesoscale eddies (with radii of 20–100 km). Ocean eddies are typically elliptical in shape, and their major axes rotate with periods of hundreds of days. In this study, we show that this slow major-axis rotation, referred to as eddy precession, is caused by the propagation of VRWs. By tracking long-term changes in eddy shape, we provide conclusive observational evidence of VRWs in the ocean, revealing a previously hidden process that could influence eddy mixing and transport.

Sack Lunch Seminar Series —
Informal seminar series within PAOC (Program in Atmospheres, Oceans, and Climate) that focuses on more specialized topics than the PAOC Colloquium. The presentations are either given by an invited speaker or by a member of PAOC and can focus on new research or discussion of a paper of particular interest.

Contact: sacklunch-committee@mit.edu