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 and the unpolluted atmosphere. While many studies exist, the vertical distribution 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 during June 1-28, 1994. Daytime H2O2 levels ranged from 0.064 to 0.505 ppbv, with the mean value being 0.175 +/- 0.077 ppbv. Typically, H2O2 levels generally increase with increasing O-3, temperature, flight altitude, and UV Bur. Conversely, a strong negative correlation with relative humidity is observed. Negative correlations with SO2 are also observed if significant concentrations are present, as in plumes. However, in a fresh plume from a fossil fuel-burning ship, nonzero H2O2 concentrations persist. The vertical profile of H2O2 shows a maximum that generally occurs above the top of the marine boundary layer, at an altitude up to 200-300 m above thr top of the marine boundary layer. (C) 1999 Academic Press.