In August 2020, the observations of total peroxy radical concentrations were carried out in the western suburb site of Hefei using a peroxy radical chemical amplifier (PERCA) instrument. The ozone production and its sensitivity were characterized with the measured O3 and its precursors. The results showed that the daily variation in total peroxy radical concentrations exhibited an obvious convex tend, with the highest value at approximately 12:00; the average peak peroxy radical concentration was 43.8×10-12; and the concentrations of the peroxy radical and ozone were driven by strong solar radiation and high temperature. The photochemical ozone production rate could be determined with peroxy radical and NO concentration. The average ozone peak production rate in summer was 10.6×10-9 h-1, which was more sensitive to NO concentration. Based on the ratio of the radical loss rate due to reactions with NOx to the radical loss rate (Ln/Q), the characteristics of O3 production in the western suburb of Hefei in summer were analyzed. The results showed that O3 production sensitivity varied greatly during the day. The summer O3 production regime shifted from the VOC-sensitive chemistry in the early morning to NOx-sensitive chemistry in the afternoon, and this regime transition typically occurred in the morning.
Keywords: ozone production rate; ozone(O3); sensitivity of ozone generation; summer in the western suburb of Hefei; total peroxy radical(RO2*·).