Very high ozone columns at northern mid‐latitudes in 2010

[1] For the year 2010, both ground- and satellite-based measurements have recorded unusually high annual mean total ozone columns over much of the Northern hemisphere. At the mid-latitude station Hohenpeissenberg (48°N, 11°E), the 2010 annual mean reached 339 Dobson Units (DU), the highest value observed since 1982, and the 8th highest in the 43 year record at Hohenpeissenberg. The 45°N to 55°N annual zonal mean exceeded 360 DU, also one of the highest values observed in the last 20 to 25 years. The 2010 annual mean was about 12 DU higher than in 2009, and almost 35 DU higher than the long-term minimum observed in 1992 and 1993. An unusually pronounced and persistent negative phase of the Arctic Oscillation and North Atlantic Oscillation in 2010, last seen in this magnitude in 1968 and 1969, and the co-incidence of northern winter 2009/2010 with the easterly wind-shear phase of the quasi biennial oscillation of stratospheric winds at the equator (QBO) have been major contributors to the high total ozone of 2010. Multiple linear regression analysis of the Hohenpeissenberg time series (since 1968) attributes about +8 DU ±2 DU (1σ) of the 2010 annual mean to the Arctic Oscillation, and about +4 DU ±1.3 DU (1σ) to the QBO. A small ozone increase since the ozone minimum of the mid 1990s might also be due to the recent decline of stratospheric chlorine and bromine.