Daytime HO2 concentrations at Oki Island, Japan, in summer 1998: Comparison between measurement and theory

Yugo Kanaya*, Yasuhiro Sadanaga, Jun Matsumoto, Usha K. Sharma, Jun Hirokawa, Yoshizumi Kajii, Hajime Akimoto

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

59 Citations (Scopus)


The daytime variation of hydroperoxy (HO2) radical concentration was observed by an instrument based on laser-induced fluorescence with NO addition at Oki Island, Japan, in July/August 1998. Although OH was not detected due to the high detection limit of the instrument, HO2 was determined with the detection limit of 0.8 parts per trillion by volume (pptv) (S/N=2, integration time of 1 min). On average, HO2 showed a maximum concentration of around 9 pptv in the early afternoon hours. During the field campaign, chemical species and meteorological parameters such as O3, CO, nonmethane hydrocarbons(C2-C6), NO/NO2, HCHO/CH3CHO, SO2, HNO3 and J(NO2) were also observed. Unfortunately, the absolute value of J(O1D) was not measured. Model calculations for radical concentrations were performed and they were compared to the observed hourly HO2 concentrations. On August 9 the calculated HO2 matched the observation very well within the uncertainties of observations (± 26%, 1σ) and the model (± 24%, 1σ). This indicates a good performance of model calculations in estimating HO2 under certain conditions with plenty of isoprene. On other days, however, model usually overestimated HO2 by a factor of 2, especially in the hours around noon. It is deduced that some important HOx loss chemistry is missing in the model. Although the cause of the discrepancy is not fully understood, possible mechanisms to explain the overestimation are studied. A hypothesis with additional loss of HO2 would be more plausible than that with additional OH loss. The additional loss rate for HO2 that can reduce the calculated HO2 to the measured level was computed for each hour. Its variation correlated well with those of H2O and some photochemical products. The possibilities of HO2 loss on aerosol surface, unknown acceleration of HO2 reactions in the presence of high H2O, and HO2 reactions with carbonyl species are discussed.

Original languageEnglish
Article number2000JD900308
Pages (from-to)24205-24222
Number of pages18
JournalJournal of Geophysical Research Atmospheres
Issue numberD19
Publication statusPublished - 2000 Oct 16
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology


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