MEASUREMENT OF PEROXIDES AND RELATED SPECIES IN THE 1993 NORTH-ATLANTIC REGIONAL EXPERIMENT

Gaseous peroxides were measured during the North Atlantic Regional Exp eriment (NARE) aboard the Department of Energy's Gulfstream G-1 aircra ft in August 1993. Flights originated in Halifax, Nova Scotia and cove red a region extending several hundred kilometers from the eastern edg e of the North American continent. Total peroxide concentration was do minated by H2O2 Median H2O2 concentration for all flights was 2.5 part s per billion by volume (ppbv), with the highest concentrations observ ed in spatially extensive layers between 250 and 1750 m above sea leve l. In the clean free troposphere, H2O2 concentration correlates Strong ly with the product O-3H2O, consistent with our understanding of the formation mechanism. The median peroxide concentration was 4 ppbv in p ollutant plumes, with excursions above 11 ppbv. The high concentration of H2O2 Observed, and its covariance with concentrations of anthropog enic species such as O-3, NOy, and aerosol particles is attributed to the aging of polluted air masses advected from the continent in stable layers.