© Author(s) 2006. This work is licensed under a Creative Commons License. Atmospheric Chemistry and Physics

Abstract. The MOZAIC programme collects ozone and wa-ter vapour data using automatic equipment installed on board five long-range Airbus A340 aircraft flying regularly all over the world since August 1994. Those measurements made be-tween September 1994 and August 1996 allowed the first ac-curate ozone climatology at 9–12 km altitude to be generated. The seasonal variability of the tropopause height has always provided a problem when constructing climatologies in this region. To remove any signal from the seasonal and synop-tic scale variability in tropopause height we have chosen in this further study of these and subsequent data to reference our climatology to the altitude of the tropopause. We de-fine the tropopause as a mixing zone 30 hPa thick across the 2 pvu potential vorticity surface. A new ozone climatology is now available for levels characteristic of the upper tropo