ABSTRACT:
The banded circulation patterns seen in the atmospheres of the gas giants are thought to arise from turbulent mixing of a nearly conserved scalar called potential vorticity. These patterns are characterised by strong eastward flows or “jets”, with weaker westward return flows between. The jets coincide with sharp gradients of potential vorticity. In extreme circumstances, the gradients can become so sharp that the meridional profile
of potential vorticity resembles a “staircase”. Similar structures are found in the terrestrial atmosphere and oceans, though jets are significantly more wavy and ephemeral. This talk examines results from an idealised single-layer shallow water model. This model captures a number of observed characteristics and, importantly, clarifies the role of forcing and damping in the emergence of jets.
ADDITIONAL INFORMATION: David Dritschel’s interests are in combining theoretical analysis and numerical computation in the study of fundamental aspects of atmospheric and oceanic fluid dynamics, and in particular vortex dynamics. He is also studies roles played by potential vorticity in the emission, propagation, scattering, reflection and refraction of internal gravity waves.
http://www.mcs.st-andrews.ac.uk/homepages/dgd1.html