Hydrogen peroxide and ozone over the northeastern United States in June 1987

Continuous measurements of ozone (O 3 ) and hydrogen peroxide (H 2 O 2 ), and of other trace gases and meteorological parameters, were made using the NOAA King Air research aircraft. The atmosphere was sampled at various elevations from minimum altitude above ground level up to 4 km above sea level, over the northeastern United States between Columbus, Ohio, and Saranac Lake, New York, during June 1987. The average O 3 concentrations, calculated for constant‐altitude flight segments, are in the range 50–110 ppbv; the H 2 O 2 range for the same flight segments is 0.6–3.6 ppbv. Concentration profiles of O 3 show little variation with altitude, with the exception of samples taken in polluted areas. The highest H 2 O 2 concentrations are observed at the lowest altitudes in air from southern regions, i.e., in air containing the greatest water vapor density. The concentrations of both O 3 and H 2 O 2 show a clear decrease from lower (40°N) to higher (44°N) sampling latitudes.