Diagnosis of the Stratospheric Ozone Budget in the Southern Hemisphere
Lower Stratosphere
 
Wuhu Feng and Martyn Chipperfield
School of the Enviroment, University  of Leeds, LS2 9JT, Leeds, UK
Howard Roscoe
British Antarctic Survey, Cambridge, UK
 
In the lower stratosphere ozone changes are determined by both chemistry
and dynamics. Quantitatively, the abundance ofozone can be described by
the continuity equation, which indicates that ozone in some volume of the
atmosphere is determined by chemistry (including O3 photochmeical
production and loss terms) and atmospheric transport (including ozone
horizontal flux divergence and diabatic terms). Here, the stratospheric
ozone budget over Antarctic polar vortex area during Spring 1999 (period
of APE-GAIA campagaign) will be diagnosed using the output from the
SLIMCAT 3-D chemical transport.
 
The model has been run in two different configurations with a variety of
resolutions and with different wind fields.  One configuration uses
24-hourly horizontal winds and temperatures from UKMO analyses (2.5
latitude x 3.75 longitude resolution, 22 isobaric levels from 0.3hPa
down to 1000hPa), the other configuration uses the 6-hourly T42L50 ECMWF
operational analyses. The differences between these versions of the
model show that UKMO simulation appears better based on APE-GAIA
comparison, and the ECMWF simulation leads to more ozone loss in mid/high
latitude and colder in the polar vortex.
 
The ozone change budget diagnoses show that ozone change is similar to
chemical loss rate, the ozone is horizontal transported out of the
midlatitudes and into the high latitudes, but difference below/above 475K
near south pole, and the ozone is downward transport into the mid/high
latitudes due to diabatic term, the contributions of catalytic cycle to
the total ozone loss rate show that ClO+ClO and ClO+BrO reaction is
important in the polar vortex, but ClO+ClO is most important below 400K.