Summary: | Recent work with high resolution, one-layer numerical models of fluid flows resembling those in the real stratosphere has suggested that: (1) the interiors of strong cyclonic vortices like the Antarctic polar vortex may be almost completely isolated laterally from their surroundings - perhaps even completely isolated, under some circumstances; (2) by contrast, material near the edge of such and isolated region can easily be eroded (or mixed one-sidedly) into the surrounding region; and (3) the erosion characteristically produces extremely steep gradients in isentropic distributions of potential vorticity (PV) and of other tracers, possibly down to horizontal length scales of a few kilometers only. Such length scales may occur both at the edge of the main polar vortex and in smaller features outside it, such as thin filamentary structures, produced by the erosion process.
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