In this paper we have tried to show that the ozone variation along the polar front zone is very dependent on dynamical processes in the atmosphere. We have used the 500 hPa level to show that there is ascending motion at 100 hPa for south and southwesterly wind flows at 500 hPa, whereas west and northwesterly flows give descending motion at 100 hPa level. The vertical velocities at 100 hPa are remarkably large. We have examples of 7 hPa/h, which corresponds to approximately 500 m/h. These strong vertical velocities are usually set up by mountain ranges and strong horizontal wind flows. Since the vertical motion is transported eastwards by the strong westerlies, the effect on the ozone values will show up to the east of the strongest vertical motions. The dominating wind flow over the Atlantic in the winter is southwesterly, This results in low stratospheric temperatures and low ozone values over the Scandinavian sector. Over western Siberia and Russia a high pressure dominates the general winter circulation. To the east of the high the dominating wind flow will be west and northwesterly, and, combined with the mountain ranges east of the Baikal Sea, this leads to general descending motion over eastern Siberia and Kamchatka. This descending motion will raise the temperature in the lower stratosphere and is well correlated with the increase in ozone. The ozone increase is, however, caused by the lowering of the tropopause and, thereby, the vertical stretching of the ozone layer.
