Correlations between CO, NOy, O3 and non-methane hydrocarbons and their relationships with meteorology during winter 1993 on the North Norfolk Coast, U.K.

Measurements of carbon monoxide and other pollutants were performed in a study of polluted air masses during winter at a time when atmospheric reactivity is low. Data collected during the Weybourne atmospheric observatory winter experiment in 1993 on the North Norfolk Coast, U.K. showed that CO is correlated with other atmospheric species and these correlations are influenced by both chemical and dynamical processes in the lower troposphere. A high pollution event occurred at the beginning of the campaign with freshly polluted air masses high in CO and nitrogen oxides coming from continental Europe via London. Very low concentrations were experienced towards the end of the period when maritime Atlantic air was reaching the site. CO showed strong positive correlation with NOy and non-methane hydrocarbons (NMHCs) as a result of common sources. Correlations between CO and ozone were strong and consistently negative due to titration of ozone by NO. CO in the background atmosphere in winter was estimated to be 122 ppbv, at a corresponding O3 concentration of 33 ppbv. Detailed analysis of the pollution event revealed that the polluted airmass originated in London some 9 h before reaching Weybourne. Differential decomposition of specific hydrocarbons en route is indicative of daytime hydroxyl radical concentrations of the order of 3×105 cm-3.