| Summary: | International audience The amount of ozone depletion in the Arctic has been monitored every year since 1994 by comparison between total ozone measurements of the SAOZ / NDACC UV-Vis spectrometer stations and 3-D chemical transport model simulations in which ozone is considered as a passive tracer. The destruction is found to be highly dependent on the stratospheric temperature history of the winter, varying between 0-10% in relatively warm and short vortex duration years to 25-30% in colder and longer ones. Compared to these 17 previous years, the winter 2010/2011 displays an unprecedented depletion of 39% in the polar vortex. The destruction started in early January and remained limited to 10% until mid-February. However, the depletion accelerated afterwards and a daily loss rate of about 0.8 DU/day was estimated until late March. Analysis with ozonesonde measurements from Sodankyla launched on March 30, also showed a reduction of about 80% of ozone between 18 and 21 km consistent with the total column loss estimations. This unusual depletion is attributed to an extremely cold stratosphere during the late winter, colder than any year since 1994 in March, due to the limited amplitude of planetary waves in 2010/2011. It is shown to even exceed that of 1997 when the vortex remained until early April. Although extreme and reaching in March a rate similar to that of September over Antarctica, the depletion is still smaller than that derived by the same method in Antarctica for 23 years, where, with the exception of 2002, it systematically reaches 50-52%. The event offers a challenging opportunity for testing the ability of 3-D chemical transport models to capture the depletion under these extreme Arctic conditions. In this study, the loss is shown to be underestimated by REPROBUS and overestimated by SLIMCAT. Possible reasons for this will be discussed.
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