Five years of observations of ozone profiles over Lauder, New Zealand

[1] Altitude profiles of ozone (O-3) over Lauder (45degreesS, 170degreesE) performed using a lidar, ozonesondes, and the satellite-borne Stratospheric Aerosol and Gas Experiment (SAGE II) instrument are presented. These data form one of the few long-term sets of O-3 profiles at a Southern Hemisphere location. In the 5 years of data presented, the dominant variation is the annual cycle, the phase and amplitude of which differ below and above 27.5 km. Superposed are irregular episodic variations, caused by various processes. The first process studied is stratosphere-troposphere exchange, characterized by dry and O-3-rich air residing in the troposphere, which was found in 21% of the measurements. The second relates to the positioning of the higher polar vortex over Lauder, often in combination with the exchange of air between midlatitude and subtropical stratospheric regions. We present examples of this which were observed over Lauder during the 1997 winter. This winter was selected for further study because of the record-low O-3 amounts measured. The third process is mixing of O-3-depleted vortex air with midlatitude air after the vortex breakup. We present one example, which shows that a filament originating from the depleted Antarctic vortex significantly lowers O-3 amounts over Lauder around 27 November 1997. There is thus a connection between Antarctic O-3 depletion and later decrease of O-3 amounts at a Southern Hemisphere midlatitude location, namely Lauder.