title: Derivation of Hydroperoxyl Radical Levels at an Urban Site via Measurement of Pernitric Acid by Iodide Chemical Ionization Mass Spectrometry.
abstract: Hydroperoxyl radical (HO2) is a key species to atmospheric chemistry. At warm temperatures, the HO2and NO2come to a rapid steady state with pernitric acid (HO2NO2). This paper presents the derivation of HO2from observations of HO2NO2and NO2in metropolitan Atlanta, US, in winter 2014 and summer 2015. HO2was observed to have a diurnal cycle with morning concentrations suppressed by high NO from the traffic. At night, derived HO2levels were nonzero and exhibited correlations with O3and NO3, consistent with previous studies that ozonolysis and oxidation by NO3are sources of nighttime HO2. Measured and model calculated HO2were in reasonable agreement: Without the constraint of measured HO2NO2, the model reproduced HO2with a model-to-observed ratio (M/O) of 1.27 (r = 0.54) for winter, 2014, and 0.70 (r = 0.80) for summer, 2015. Adding measured HO2NO2as a constraint, the model predicted HO2with M/O = 1.13 (r = 0.77) for winter 2014 and 0.90 (r = 0.97) for summer 2015. These results demonstrate the feasibility of deriving HO2from HO2NO2measurements in warm regions where HO2NO2has a short lifetime.
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , 311 Ferst Drive, Atlanta, Georgia 30332, United States.
authors.forename: Dexian
authors.identifier: 0000-0001-6963-5205
authors.initials: D
authors.lastname: Chen
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , 311 Ferst Drive, Atlanta, Georgia 30332, United States.
authors.forename: L Gregory
authors.initials: LG
authors.lastname: Huey
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , 311 Ferst Drive, Atlanta, Georgia 30332, United States.
authors.forename: David J
authors.initials: DJ
authors.lastname: Tanner
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , 311 Ferst Drive, Atlanta, Georgia 30332, United States.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Li
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , 311 Ferst Drive, Atlanta, Georgia 30332, United States.|School of Chemical and Biochemical Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Nga L
authors.initials: NL
authors.lastname: Ng
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , 311 Ferst Drive, Atlanta, Georgia 30332, United States.
authors.forename: Yuhang
authors.initials: Y
authors.lastname: Wang
mesh_terms: D007454:Iodides; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D012621:Seasons; D013696:Temperature
chemical_list: D007454:Iodides