Daily and hourly environmental and meteorological observation data in Huizhou of Guangdong Province during 2013-2016 were used to analyze the characteristics of ozone pollution in summer and autumn

and the ozone pollution process on July 12-13

2013 was analyzed. The results show that: ① Ozone pollution appeared in all seasons with the average number of days of 12.5 in summer and autumn accounting for 73.5% of the annual ozone pollution days. The frequency of occurrence of westerly wind (WSW-W-WNW-NW) in summer and autumn during ozone pollution days and ozone moderate pollution days were 44.9% and 74.4%

respectively. In summer and autumn

most of the ozone pollution days occurred in weather conditions with hot and sunny weather

abundant sunshine and westerly wind. The climate characteristics in summer and autumn make a high-risk period for ozone pollution. ② The ozone pollution process on July 12-13

2013 was mainly affected by the sinking of the “Su Li” and the westerly airflow. Hot and sunny weather and abundant sunshine were beneficial to ozone generation

the westerly winds on the ground and low-altitude make Huizhou in the downwind direction of the Pearl River Delta urban group

which led to regional pollution transport

while the vertical downdraft was not beneficial to pollutant transport and diffusion.