Zonal asymmetry in ozone mixing ratio was observed by POAM II during the 1994-1996 summers between 55 ¿N and 65 ¿N and between 21 km and 28 km in altitude. The zonal variance can be described as persistent large-scale ozone patterns that move approximately with the zonal mean wind. The histories of air parcels observed by POAM are deduced from 20-day back trajectories using UKMO winds which have been corrected for stationary anomalies. The ozone mixing ratio is found to correlate with the average latitude of the back trajectory throughout the summer, indicating that the zonal variance is a result of meridional transport. The meridional transport appears to be caused by breaking of westward-propagating waves that are evanescent in the summer easterly flow. ¿ 1999 American Geophysical Union