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FP5

QUILT Report Summary

Project ID: EVK2-CT-2000-00059
Funded under: FP5-EESD
Country: France

Ozone loss during Arctic winters

As during preceeding winters, the total ozone reduction inside the vortex was quantified during the winter of 2001/2002, 2002/2003 and 2003/2004. The analysis is based on the total ozone measurements of the Arctic SAOZ network from which the contribution of transport has been removed using the 3D CTM REPROBUS model.

Winter 2001/2002: The temperature at 475 K was below TNAT from mid-December to early January. Otherwise, the temperature was warm. There was only few possibilities for PSC occurrences, during two periods, one in mid-December and one around January 10. That winter was a rather "warm" winter. The final warming occurred in early March. The vortex formed in December 2001 and was persisting until early April. At that date, two bubbles of vortex were well separated. Two periods of O3 reduction are observed, one around mid-December and one in mid-February/early March. During that period the loss was at a rate of 0.25% per day. The cumulative loss at the end of the winter is 10% which corresponds to ~ 46 DU.

Winter 2002/2003: The temperature was below TNAT at all levels from end of November to January 15, and the temperature was very cold, around TICE, at the beginning of December. The final warming occurred after March 22. The vortex was persisting until early April. Three periods of O3 reduction are observed, one in December and one in January at a rate of 0.4% per day and one in end of February at a rate of 0.5 % per day. The cumulative loss at the end of the winter is 23 % which corresponds to ~90 DU.

Winter 2003/2004: During the winter of 2003/2004, in early December, the vortex was compact and in coincidence with the cold temperature areas. On 24 December, the vortex was elongated, extending down to Southern France that is to sun-illuminated regions. The situation was very similar during the whole month of January. On January 30, the vortex was split in two bulbs, which recombined, by Mid-February. During the second part of February, the vortex was small, the temperature was increasing and cold surface area was vanishing. In March, the small remaining bulb of vortex is compact and cantered on the pole. In April, the temperature was above 203K at all levels. During the month of December, no loss is observed. A reduction at a rate of 0.3% /day is observed during the first twenty days of January, then the loss rate increases up to 0.5% /day between January 20 and February 10. No loss is observed after that date. The cumulative ozone loss during that winter is 18% corresponding to 90 DU.

In addition, experimental results since 1993/1994 have also been compared to 3D CTM multi-annual simulations in order to verify the ability of models to reproduce the ozone loss in a variety of meteorological conditions (cold vortex early in the season with little sunlight or at the opposite, cold and persistent vortex until April, etc.) and chlorine loading. In their most updated version, both model SLIMCAT and REPROBUS, are correctly reproducing the observed ozone loss.

More information on the QUILT project can be found at: http://nadir.nilu.no/quilt/index.php.

Related information

Contact

Florence GOUTAIL, (Scientist)
Tel.: +33-1-64474289
Fax: +33-1-69202999
E-mail
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