Patterns of Barotropic Vortex in a Rotating Fluid and the Structural Rotation of Tripolar Vortex

In this study, the patterns of barotropic vortices and their structural rotation were investigated through laboratory experiments. Both stable and unstable barotropic vortices were formed in a rotating water tank with a rotating circular plate depending on the diameter, direction, and speed of rotating circular plate. The patterns of stable vortices turned out to be tripolar, triangular, rectangular, and monopolar vortex. These vortex patterns were affected by the gap between the circular plate and the wall of the water tank. Many unstable vortices were formed by anticyclonically and highly rotating circular plate. These results were caused by the centrifugal instability. The structural angular velocity of the tripolar vortex increased with the tangential velocity of the circular plate. The anticyclonic tripolar vortex had higher structural angular velocity than the cyclonic vortex. The tripolar vortex in the water tank was very similar with the real oceanic tripolar vortex from the view point of the Rossby number and the structural rotation.