Update of the Situation in the Arctic Ozone Layer

2nd March 2005

Meteorology:
Over the past few days a minor warming has taken place which reached its peak activity during the past weekend. Overall the dynamical activity connected with the warming is now decreasing. Despite the warming the vortex in the lower stratosphere is still stable, and meteorological forecasts indicate that it is likely to remain so for at least the next week. The warming ended the period of record PSC extent, but smaller areas of PSC conditions are still present in parts of the vortex and the conditions are still considerably colder than average. The average PSC extent during this winter is already 25% larger than during any winter since regular observations started about 40 years ago. Due to ongoing PSC activity this value will further grow.

(Analysis based on ECMWF data processed by DMI/NILU/AWI: http://www.awi-potsdam.de/www-pot/atmo/met/pv.html http://www.awi-potsdam.de/www-pot/atmo/met/psc1.html and by FU-Berlin: http://strat-www.met.fu-berlin.de/)

Ozone loss:
Results from the international ozonesonde station network shows that around 19 km altitude ozone loss in the outer half of the polar vortex reached 40% and ozone is still rapidly being destroyed. Significant loss also started in the core of the vortex which is now getting more and more exposed to sunlight. Significant ozone loss extends from 15 to 22 km altitude, and in the outer half of the vortex chemical loss has to date destroyed about 10-15% of the overall thickness of the ozone layer. So far this chemical loss has been largely balanced by the normal dynamical supply of ozone to the Arctic with the result that the total thickness of the ozone layer inside the vortex has remained unchanged since December, in contrast to the normal seasonal increase in total ozone during this season. These observations are confirmed by analyses of the POAM III and SAGE III satellite instruments.

(Analysis based on data from WMO-GAW ozonesonde station network, NASA (SAGE), and NRL (POAM).