Many ECC-type ozonesondes were launched at the Canadian Arctic Eureka observatory (2*ῌN, 20ῌW), one of the most northern stations in the Arctic, during winters from +33-/3. to ,**+/*" and the temporal evolutions of the vertical ozone profiles were obtained in detail. The lower stratospheric temperature over Eureka was very low inside the polar vortex and the largest ozone loss was observed in +333/,***, as reported in a previous paper. Similarly, Eureka was often or persistently inside the

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... x in the lower stratosphere (around the .1* K isentropic surface level) in the winters of +33./3/, +33//30, and +330/31. Very low temperatures were observed inside the vortex in the lower stratosphere over Eureka, as indicated by detection of PSCs by Mie lidar. Observations of tracers (N,O, total reactive nitrogen species (NOy), and others) inside the vortex during these winters using an ER-, aircraft and balloons indicated that the e#ect of air parcel mixing across the vortex edge was minimal, based on the tracer-tracer relationship (e.g., Y. Kondo et al.; J. Geophys. Res., +*.D, 2,+/, +333). Therefore, significant decreases of the intravortex ozone mixing ratio in the lower stratosphere were considered to be chemical ozone losses due to chlorine activation of PSCs following diabatic descent. The apparent ozone loss rate inside the vortex over Eureka was estimated for each year. The rates ranged from *.*+ to *.*ppmv/day, less than that observed in +333/,*** (*.*. ppmv/day). The observations were conducted at a single station; however, the apparent ozone loss rate over Eureka inside the vortex each year agrees with loss rates obtained in other studies.