In situ, gas chromatographic measurements of non-methane hydrocarbons and dimethyl sulfide at a remote coastal location (Mace Head, Eire) July-August 1996

Atmospheric non-methane hydrocarbons (NMHC) and dimethyl sulfide (DMS) have been monitored at a remote coastal location (Mace Head, fire) using adsorption sampling techniques with analysis by in situ gas chromatography as part of the ACSOE OXICOA 1996 campaign. Concentrations varied considerably during the campaign but can be consistently interpreted by consideration of the relevant back-trajectory of the monitored air mass. Isoprene is confirmed as the most important NMHC in determining OH removal, contributing to up to 20%. Isoprene shows strong diurnal variations, although the structure of the diurnal pattern depends on the origin of the air mass. In contrast to previous studies, DMS concentrations during the campaign appeared to show no consistent diurnal variation.