THE IMPACT OF TROPOPAUSE VARIATION ONOZONE DISTRIBUTION IN UPPER TROPOSPHERE/LOWER STRATOSPHERE

The upper troposphere/lower stratosphere (UT/LS), as a special region, lies between 8 and 25 km altitude. Because most of ozone column resides in the lower stratosphere, small change in ozone abundance could have a large impact on climate and the surface UV flux. The tropopause, as an interface or transition zone between the well mixed, ozone-poor upper troposphere and the stratified, ozone rich lower stratosphere, has its seasonal and long-term variation trends which in turn could lead to a direct and evident effect on the distribution of atmospheric ozone and its column abundance. This work simulated the impact of tropopause variation on the distribution of ozone in UT/LS with a two-dimensional model named SOCRATES (Simulation Of Chemistry, Radiation, And Transport of Environmentally important Species). The model, developed in the Division of Atmospheric Chemistry of NCAR, is one coupling chemical, radiative, and dynamical processes. Its domain and resolution are 0-120 km and 1 km in vertical and 85S-85N and 5?in horizontal. Model simulation results show that the annual cycle of the tropopause height has remarkable impact on the ozone distribution in the UT/LS. The local change of ozone can be more than 10%. When the tropopause is increased by 1 km in winter in middle latitudes of Northern Hemisphere, the impact on ozone distribution is evident and the local change of ozone can be more than 6%. However the impact on total ozone is relatively small, less than 5 Dobson units. This is much less than the statistic results between tropopause height and total ozone from data analysis.