A total of 197 ozone profiles were obtained from the nine Arctic ozone sounding stations of Alert, Resolute, Ny ¿lesund, Heiss Island, Bear Island, Ammassalik, Scoresbysund, Sodankyl¿, and Lerwick during January--March 1989. The sounding stations cover the latitude range from 60 ¿N to 83 ¿N and the longitude range from 95 ¿W to 58 ¿E. It was, for the first time, possible to get a detailed picture with a 150-m resolution of the vertical distribution of ozone during winter and spring over extended areas of the north polar region. The fine structure of the Arctic ozone distribution shows considerable layering in profiles obtained outside and at the edge of the polar vortex, whereas little layering is found in profiles obtained well inside the vortex. The lowest temperatures were found at the edge of the vortex, e.g., at or below -90 ¿C during January 30--31 at Lerwick and close to -90 ¿C on January 24 at Bear Island at the altitudes of 20--25 km. Temperatures below -77 ¿C, the condition for the formation of the type I polar stratospheric clouds (PSCs), were common during January and early February 1989 in the Arctic. Possibly as a consequence of the heterogeneous processes in the presence of PSCs, the ozone mixing ratios decreased, especially during late winter when the sun's irradiation intensifies in high latitudes. A trend of -0.1%/d around 80 ¿N latitude was found in the altitude range of 420--600 K potential temperature during the period January 10 to February 13, 1989, increasing to -0.4%/d when the later period January 24 to February 13, 1989, is considered. If one were to take into account the downward diabatic motion (2.6 km/month) the negative trends would increase further by about -0.4%/d in magnitude. ¿ American Geophysical Union 1992