Relationships between ozone and other photochemical products at Ll. Valby, Denmark

The representativeness of the monitoring station at Ll. Valby, Denmark, has been tested. Furthermore, the relation of gaseous NOy and O3 is investigated. From the linear orthogonal regression analyses of Ox (sum of O3 + NO2) and other photochemical products measured at Ll. Valby Denmark and from literature results it is estimated that the non-photochemical background mixing ratio of O3 in the Northern Hemisphere is 24 ± 6 ppbv. The correlation of HCOOH and CH3COOH with Ox indicates that these acids are of photochemical origin. A high correlation of HNO3 with Ox is also found. The anti-correlation of O3 with MSA observed in this study (methane sulphonic acid) indicates that O3 at Ll. Valby, Denmark, is produced by emissions from land sources. Finally, evidence is found that NO3 reactions is only a supplementary source of unidentified nitrogen species in the troposphere.