Total ozone during the 88‐89 Northern Hemisphere winter

Total ozone values measured by the Total Ozone Mapping Spectrometer (TOMS) during January, February and March 1989 are analyzed. During this period, polar total ozone values did not reveal clear depletions, although average winter total ozone values indicate that a 2–6% ozone reduction has occurred in northern mid to high latitudes over the last 10 years. Rapid total ozone increases were seen during mid‐February, resulting from a wave 2 major stratospheric warming. In order to track polar air over the warming period, total ozone trends are further analyzed using Ertel's potential vorticity.