A two-dimensional (2-D) zonally averaged chemistry-transport model of the stratosphere has been extended to include some zonally asymmetric effects to study the chemically disturbed conditions in the Arctic winter during the occurrence of polar stratospheric clouds (PSCs). The model allows air parcels that have been in PSCs in the polar night to be exposed to sunlight during the passage south through a wave trough. Large enhancements of ClO are estimated as well as significant ozone reductions, most pronounced around the 20 km height level. The ozone depletions maximize in late March, about one month after the cease in PSC activity in the model, and amount to 5--8% in column ozone at 70¿N. In agreement with column measurements made from the DC-8, the model estimates an increase in the columns of HNO3 and ClONO2, and a decrease in the HCl column within the polar vortex. ¿ American Geophysical Union 1990