Statistical characteristics of secondary ozone density peak observed in Korea

Statistical characteristics of secondary ozone density peak in the upper tropopause are analyzed from the 9-year ozonesonde measurements of density profiles at Pohang, Korea, combined with 11-year satellite measurements of the HALOE onboard the UARS. These secondary peaks, about 80% of them associated with the downward transport in isentropic coordinates for the previous 24 h are observed at altitudes of about 14 km in winter and spring time. Enhanced temperatures are also observed clearly near the peak. The backward trajectory model, HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) is used to light these events in terms of transport. Slow increase in the frequency of the secondary peak appearance was found with time at rates of 0.82-1.5%/yr, which indicates increasing stratosphere-troposphere mass exchange during the period.