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AGU: Geophysical Research Letters

 

Index Terms

  • Atmospheric Composition and Structure: Chemical kinetic and photochemical properties
  • Atmospheric Composition and Structure: Biosphere/atmosphere interactions
  • Atmospheric Composition and Structure: Constituent sources and sinks
  • Atmospheric Composition and Structure: Troposphere—composition and chemistry

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 29, 1212, 4 PP., 2002
doi:10.1029/2001GL014061

Implications of iodine chemistry for daytime HO2 levels at Rishiri Island

Yugo Kanaya

Atmospheric Composition Research Program, Frontier Research System for Global Change, Yokohama, Japan.

Yoko Yokouchi

National Institute for Environmental Studies, Tsukuba, Japan.

Jun Matsumoto

Research Center for Advanced Science and Technology, the University of Tokyo, Tokyo, Japan.

Kenji Nakamura

Research Center for Advanced Science and Technology, the University of Tokyo, Tokyo, Japan.

Shungo Kato

Research Center for Advanced Science and Technology, the University of Tokyo, Tokyo, Japan.

Hiroshi Tanimoto

National Institute for Environmental Studies, Tsukuba, Japan.

Hiroshi Furutani

National Institute for Environmental Studies, Tsukuba, Japan.

Kenjiro Toyota

Atmospheric Composition Research Program, Frontier Research System for Global Change, Yokohama, Japan.

Hajime Akimoto

Atmospheric Composition Research Program, Frontier Research System for Global Change, Yokohama, Japan.

The observed midday maximum in the mixing ratio of HO2 at Rishiri Island in June 2000 was ∼10 pptv, but photochemical box model simulations overpredicted HO2 at this location by an average of 70%. This overestimation was significant only when the mixing ratio of NO was lower than 300 pptv, and was coincident with overprediction of the NO/NO2 ratio. We detected several organoiodines, presumably emitted from seaweeds, and propose the presence of the IO radical. IO could reduce HO2 mixing ratios via the formation of HOI that may subsequently be scavenged by aerosols or lost by photolysis and may also convert NO to NO2 directly. Model calculations with known iodine chemistry could reproduce the observed HO2 with 12–25 pptv of IO. Although iodine chemistry is unlikely to explain the entire discrepancy in HO2, several pptv of IO could significantly reduce HO2 mixing ratios and NO/NO2 ratios.

Published 20 April 2002.

Citation: Kanaya, Y., Y. Yokouchi, J. Matsumoto, K. Nakamura, S. Kato, H. Tanimoto, H. Furutani, K. Toyota, and H. Akimoto (2002), Implications of iodine chemistry for daytime HO2 levels at Rishiri Island, Geophys. Res. Lett., 29(8), 1212, doi:10.1029/2001GL014061.

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