Analysis of observed ozone episode in urban Jinan, China.

Using a trajectory model (HYSPLIT) analyzed the ozone episodes observed at urban Jinan in 2005. There were 84 h (in 24 days) of ozone episodes (>100 ppbv) observed during the study. June was the most polluted month in the year. The earliest episode observed in May 4 was mainly caused by the favorable meteorological condition for ozone production and accumulation. A multi-day episode from 6 to 8 June was related to the passage of typhoon Nesat. 39 h (in 11 days) of ozone episodes were observed from June 10 to 24. Large scale stagnation, recirculation of air mass, intense solar radiation, high temperature and long-rang transport of pollutants were the main reason for the ozone episodes during this period.