Stratospheric Polar Vortices
A prominent feature of Earth's stratosphere (10-50km) are cyclonic vortices
which form over the winter poles. These vortices play an
important in the coupling between the troposphere and stratosphere
(e.g., Arctic Oscillation) and in ozone depletion (e.g., Antarctic Ozone
The structure and evolution of the Antarctic polar vortex in 1996 is
shown in the animation of Potential vorticity (PV) from UKMO
Sean Winkler's web site.
The vortex can also be seen in maps of trace constituents, e.g.,
animation below of CRISTA
measurements of nitrous oxide mixing ratios
at a pressure-altitude 10 hPa (about 30 km)
Michael McIntyre's web site.
Further illustrations of the Antarctic polar vortices can be seen in images of
column-integrated ozone. The image below shows total ozone in October
1991, as measured by the TOMS instrument, with very low
values (the "ozone hole") confined within the Antartic polar vortex.
The isolation of air inside the vortex is highlighted in the image below
which shows measurements of four different constituents from UARS
satellite. There is a large difference in all constituents between
inside and outside the vortex (black curves show the vortex edge
region defined using potential vorticity).
The impact of the vortex on the Antarctic Ozone Hole was clearly
illustrated in September 2002, when large scale wave activity split
the polar vortex, and ozone hole, into two sections. The image below
contrasts the ozone hole between September 2001 and 2002.
High resolution trajectory calculation show fine scale structure
around the polar vortex and the transport of vortex air into the middle
latitudes, as illustrated below. The reality of the fine scale
features in such calculations has been verifed by comparisons with
Courtesy of Eugene Cordero.