Hydrogen peroxide and methylhydroperoxide distributions related to ozone and odd hydrogen over the North Pacific

摘要: Hydrogen peroxide and methylhydroperoxide were measured in the troposphere over western North Pacific as part of airborne portion NASA's Global Tropospheric Experiment/Pacific Exploratory Mission-West A field mission. The flights circled Pacific, focusing on extended from 300 to 13,000 rn altitude. hydroperoxides uniquely separated quantified using a high-pressure liquid chromatography system conjunction with continuous enzyme fluorometric instrument. Results show latitudinal gradient both peroxides at all altitudes; for example, between 3 5 km, H20 2 median values decrease 1700 500 parts per trillion by volume (pptv) going 0o-15oN 45o-60oN, corresponding CH3OOH was 1100 200 pptv. Concentration maxima are observed species altitudes km concentrations below 1 lower 30%, 10% CH3OOH, even lower, factor 10, above 9 km. ratio increased altitude latitude ratios midlatitude high Highest encountered Celebes Sea air which impacted aged biomass fire urban pollutants. level detection stratospheric air. exceeded SO2 95% time, exceptions generally Above 03 increases decreasing CH3OOH. Below O3-CH3OOH trend is same but increasing 2. measurements compared predictions based upon photochemical steady state zero-dimensional model three-dimensional mesoscale time-dependent model. These models capture trends possible exception where surface removal important. lifetime 3.5 days brings model-estimated into agreement. suggests strong correlation NO/CO or HO2/HO H202/CH3OOH. hydroperoxide bracket modeled relationship occasionally much than expected.