The contribution of the ozonolysis of terpenes to tropospheric OH concentrations

The recent finding that OH is formed as a direct product of the ozonolysis of terpenes is used to investigate the influence of this new OH source on the tropospheric OH budget applying model calculations. The results show that the OH production following UV photolysis of ozone leads to the main competition for ozonolysis at daytime. OH may increase considerably in its concentration as a result of the ozonolysis of terpenes at low photolysis frequencies, however, at high photolysis frequencies and moderate NOx concentrations this effect is reversed due to the fast reaction of OH with terpenes. At night ozone competes with NO3 in its reactions with the terpenes. Integrated over a full day of 24 h the terpene reactions lead to a source of OH in the troposphere. PACS No.: 82.40We