2018 Volume 53 Issue 1 Pages 1-12
Organic nitrates, ONs, are produced together with ozone (O3) by photochemical reactions in the troposphere. The branching ratio, α, between ONs and NO2 formation after the reaction of NO with peroxy radicals, RO2, can influence the ozone formation. Observations of ONs are insufficient in suburban areas in Japan. In this study, an observation of ONs was conducted at a suburban site in Tokorozawa, Saitama, in the summer of 2015. An analyzer based on the thermal dissociation/cavity-attenuated phase shift (TD/CAPS) method was utilized. Consequently, ONs were successfully monitored for 3 days when total oxidants (=NO2+O3) was 152 ppbv at most. After data filtering by the short-term variation of NO2, the correlation between ONs and total oxidants was explored. Based on the slope of the regression line, α was determined to be 0.04 on average. The branching ratio of ONs formation for the downtown air mass (α=0.05) was greater than that for the suburban case (α=0.02).
