Arctic ozone loss in threshold conditions: Match observations in 1997/1998and 1998/1999

Citation
A. Schulz et al., Arctic ozone loss in threshold conditions: Match observations in 1997/1998and 1998/1999, J GEO RES-A, 106(D7), 2001, pp. 7495-7503
Citations number
17
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Volume
106
Issue
D7
Year of publication
2001
Pages
7495 - 7503
Database
ISI
SICI code
Abstract
Chemical ozone loss rates inside the Arctic polar vortex were determined in early 1998 and early 1999 by using the Match technique based on coordinate d ozonesonde measurements. These two winters provide the only opportunities in recent years to investigate chemical ozone loss in a warm Arctic vortex under threshold conditions, i.e., where the preconditions for chlorine act ivation, and hence ozone destruction, only occurred occasionally. In 1998, results were obtained in January and February between 410 and 520 K. The ov erall ozone loss was observed to be largely insignificant; with the excepti on of late February, when those air parcels exposed to temperatures below 1 95 K were affected by chemical ozone loss. In 1999, results are confined to the 475 K isentropic level, where no significant ozone loss was observed. Average temperatures were some 8 degrees - 10 degrees higher than those in 1995, 1996, and 1997, when substantial chemical ozone loss occurred. The re sults underline the strong dependence of the chemical ozone loss on the str atospheric temperatures. This study shows that enhanced chlorine alone does not provide a sufficient condition for ozone loss. The evolution of strato spheric temperatures over the next decade will be the determining factor fo r the amount of wintertime chemical ozone loss in the Arctic stratosphere.