H<sub>2</sub>O<sub>2</sub> and CH<sub>3</sub>OOH (MHP) in the Remote Atmosphere: 1. Global Distribution and Regional Influences
Hannah M. Allen, John D. Crounse, Michelle Kim, A. P. Teng, Eric Ray, Kathryn McKain, Colm Sweeney, P. O. Wennberg
Abstract
Abstract Atmospheric hydroperoxides are a significant component of the atmosphere's oxidizing capacity. Two of the most abundant hydroperoxides, hydrogen peroxide (H 2 O 2 ) and methyl hydroperoxide (MHP, CH 3 OOH), were measured in the remote atmosphere using chemical ionization mass spectrometry aboard the NASA DC‐8 aircraft during the Atmospheric Tomography Mission. These measurements present a seasonal investigation into the global distribution of these two hydroperoxides, with near pole‐to‐pole coverage across the Pacific and Atlantic Ocean basins and from the marine boundary layer to the upper troposphere and lower stratosphere. H 2 O 2 mixing ratios are highest between 2 and 4 km altitude in the equatorial region of the Atlantic Ocean basin, where they reach global maximums of 3.6–6.5 ppbv depending on season. MHP mixing ratios reach global maximums of 4.3–8.6 ppbv and are highest between 1 and 3 km altitude, but peak in different regions depending on season. A major factor contributing to the global H 2 O 2 distribution is the influence of biomass burning emissions in the Atlantic Ocean basin, encountered in all four seasons, where the highest H 2 O 2 mixing ratios were found to correlate strongly with increased mixing ratios of the biomass burning tracers hydrogen cyanide (HCN) and carbon monoxide (CO). This biomass burning enhanced H 2 O 2 by a factor of 1.3–2.2, on average, in the Atlantic compared with the Pacific Ocean basin.