Measurement and interpretation of concentrations of H₂O₂ and related species in the upper midwest during summer

Abstract

Measurements of H2O2 and related species were made by aircraft on 18 flights over 11 days during June 1987 over Ohio. Measurements typically encompassed an altitude range from the surface to 5.5 km above mean sea level and were conducted under a variety of meteorological conditions, but focussed on conditions conducive to the formation of convective storms. Concentrations of H2O2 ranged from <0.2 to 7 ppb and exhibited as much as a factor of 10 variability even on a given day at fixed altitude, as well as between days. Hydrogen peroxide concentration typically was low near the surface, rose to a maximum near the top of the boundary layer, then slowly decreased with altitude. In contrast, SO2 and NOy were largely confined to the surface layer. A simple photochemical calculation shows that where NOx concentrations are low, [H2O2] is strongly influenced by the water vapor concentration. The [H2O2] tracked changes in dew point, and measured and calculated H2O2 concentrations were in general agreement. The low [H2O2] in the boundary layer is ascribed to consumption of radicals by reactions other than combination reactions, and to loss of H2O2 by dry deposition. Comparison of the profile shapes for H2O2 and SO2 suggests that mixing processes will have a large influence on the extent to which these two species will react in convective systems.

Variability of SO=4, Total Sulfate, NO−3, and Total Nitrate Scavenging Ratios for the Frontal Boundary Study

“…During the FBS series, clear-air trace pollutant concentrations in the boundary layer and free troposphere, as well as those observed in-cloud, reflected features that have been noted in other airborne measurement studies (Heikes et al 1987;Boatman et al 1989;Daum et al 1990;Tremmel et al 1994). Trace pollutant profiles typical of those observed during the FBS series are illustrated in Fig.…”

Airship Measurements of Hydrogen Peroxide and Related Parameters in the Marine Atmosphere Along the Western U.S. Coast

“…To observe the vertical and horizontal distribution of H 2 O 2 , several aircraft-based overland measurement campaigns for H 2 O 2 have been performed in the United States [northeastern region (1,15), eastern region (2), central region (16), and upper midwestern region (17)]. Aside from seasonal variation, these data show a clear pattern: H 2 O 2 concentrations are low near the surface and increase with altitude to a maximum near the top of the boundary layer and then decrease slowly with further increases in altitude.…”

Aircraft and ground-based measurements of hydroperoxides during the 2006 MILAGRO field campaign

“…Under conditions where NO x is low and there are no depositional losses, we expect peroxide concentration to depend on the production rate of radicals which is proportional to the product of O 3 and H 2 O if, as is often the case, O 3 photolysis is the dominant source of radicals (Daum et al, 1990, Tremmel et al, 1993. Figure 3 illustrates the relationship between H 2 O 2 , O 3 and water vapor using all data obtained for altitudes >3500 m and [NO y ] <5 ppbv (with the exception of ferry transects to and from Veracruz).…”