The Area of the Stratospheric Polar Vortex as a Diagnostic for Tracer Transport on an Isentropic Surface

Abstract Data retrieved from the LIMS (Limb lnfrared Monitor of the Stratosphere) experiment are used 10 calculate daily isentropic distributions of Ertel's potential vorticity, ozone, water vapor and nitric acid at the 850 K level in the Northern Hemisphere stratosphere for the period 25 October 1978 through 2 April 1979. Systematic redistributions of the quasi-conservative tracers are investigated by following the evolutions of the horizontal projection of the areas enclosed by isopleths of tracer on the isentropic surface. If the horizontal velocity is nondivergent on an isentropic surface, the areas change in response to nonconservative processes and /or irreversible mixing to unresolvable scales and so provide a diagnostic for quantifying the net cited of these two processes. The effects of the seasonal variation of the solar heating on the areas are identified from the evolutions of the hemispheric means and, for the potential vorticity, from a comparison with an annual Mile integration of a zonally...