The Influence of Aqueous Phase Chemistry on Long Term Ozone Concentrations over Europe

Clouds affect tropospheric ozone levels through aqueous phase chemical reactions and by altering radiation transfer and mixing. Cloud droplets can act as important sinks for ozone and ozone precursors such as oxidized hydrocarbons and NO_Χ (NO+NO₂) through aqueous oxidation and/or wet removal. Moreover the presence of liquid water separates soluble and insoluble species which again can effect the ozone formation. For instance NO, which is relatively insoluble will be separated in the presence of cloudwater from the relatively soluble HO₂, reducing effectively the formation of ozone in the gasphase.