Airship measurements of hydrogen peroxide and related parameters in the marine atmosphere along the western US coast

Hydrogen peroxide remains a key species of interest, in both the polluted a nd the unpolluted atmosphere. While many studies exist, the vertical distri bution of H2O2 in the marine atmosphere has never been reported. This paper reports data for gaseous H2O2, O-3, and SO2 and meteorological parameters measured from an airship along the Oregon and Northern California coast dur ing June 1-28, 1994. Daytime H2O2 levels ranged from 0.064 to 0.505 ppbv, w ith the mean value being 0.175 +/- 0.077 ppbv. Typically, H2O2 levels gener ally increase with increasing O-3, temperature, flight altitude, and UV Bur . Conversely, a strong negative correlation with relative humidity is obser ved. Negative correlations with SO2 are also observed if significant concen trations are present, as in plumes. However, in a fresh plume from a fossil fuel-burning ship, nonzero H2O2 concentrations persist. The vertical profi le of H2O2 shows a maximum that generally occurs above the top of the marin e boundary layer, at an altitude up to 200-300 m above thr top of the marin e boundary layer. (C) 1999 Academic Press.