Ozone destruction and production rates between spring and autumn in the Arctic stratosphere

In situ measurements of radical and long-lived species were made in the lower Arctic stratosphere (18 to 20 km) between spring and early autumn in 1997. The measurements include O-3, ClO, OH, HO2, NO, NO2, N2O, CO, and overhead O-3 A photochemical box model constrained by these and other observations is used to compute the diurnally averaged destruction and production rates of O-3 in this region. The rates show a strong dependence on solar exposure and ambient O-3. Total destruction rates, which reach 19%/month in summer, reveal the predominant role of NOx and HOx catalytic cycles throughout the period. Production of O-3 is significant only in midsummer air parcels. A comparison of observed O-3 changes with destruction rates and transport effects indicates the predominant role of destruction in spring and an increased role of transport by early autumn.