event occurred with the vortex splitting into two
cyclonic centers. From the temperature field data it
is evident that relatively warm air extended to the
South Pole, which indicates a polar stratospheric
major warming. In this respect, the amplitude of the
zonal wave-number 2 (derived from the Fourier
analysis of the isobaric height and temperature
fields) reached the peak when the polar vortex split
into two circulations (reversal of the zonal mean
wind). The latter has also been interpreted by using
dynamical diagnostics suggested by the wave,
mean-flow interaction theory (e.g. Eliassen-Palm
flux). It is worth recalling that such a sudden
stratospheric warming is usually accompanied with
'blocking events'; these are characterised by
quasistationary distortions of the tropospheric flow.
It should be emphasised that the above-described
meteorological situation, which prevailed during
21–26/09/2002 and led to the split of the southern
ozone hole, is not identical with that during the
period of 5–13/09/2002, when a first trial of the
ozone hole to split was observed.