Localized
rapid ozone loss in the northern winter stratosphere: An analysis of
UARS observations
Journal of Geophysical Research, v. 103, pp 1555-1571,
1998
Observations of low-ozone air pockets forming during northern winter
in the middle stratosphere outside the polar vortex provide an
opportunity to test models of the photochemistry of ozone at several
altitudes, as the trajectories of the associated air parcels are
well defined by Lagrangian transport codes over the periods of
interest, and vertical profiles of key species, including ozone, are
available from instruments aboard the Upper Atmosphere Research
Satellite (UARS). We find that a Lagrangian photochemical model,
where the chemistry within an isolated parcel of air is simulated as
it travels along a specified trajectory, does reproduce the observed
formation of low-ozone pockets in the 6-10 mbar altitude range
within the measurement uncertainties but overestimates the ozone
loss rate at higher altitudes. The rapid ozone loss localized in
these pockets is due to the isolation of air at high latitudes (and
high solar zenith angles). Thus the low ozone levels are due to a
decrease in the odd oxygen production rate and not to an increase in
the loss rate by reaction with halogen species, as in the
``classical'' ozone hole.