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Implications of iodine chemistry for daytime HO 2 levels at Rishiri Island
Author(s) -
Kanaya Yugo,
Yokouchi Yoko,
Matsumoto Jun,
Nakamura Kenji,
Kato Shungo,
Tanimoto Hiroshi,
Furutani Hiroshi,
Toyota Kenjiro,
Akimoto Hajime
Publication year - 2002
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl014061
Subject(s) - mixing ratio , atmospheric chemistry , mixing (physics) , iodine , photodissociation , box model , daytime , meteorology , chemistry , atmospheric sciences , environmental science , analytical chemistry (journal) , photochemistry , environmental chemistry , ozone , geology , physics , organic chemistry , quantum mechanics
The observed midday maximum in the mixing ratio of HO 2 at Rishiri Island in June 2000 was ∼10 pptv, but photochemical box model simulations overpredicted HO 2 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/NO 2 ratio. We detected several organoiodines, presumably emitted from seaweeds, and propose the presence of the IO radical. IO could reduce HO 2 mixing ratios via the formation of HOI that may subsequently be scavenged by aerosols or lost by photolysis and may also convert NO to NO 2 directly. Model calculations with known iodine chemistry could reproduce the observed HO 2 with 12–25 pptv of IO. Although iodine chemistry is unlikely to explain the entire discrepancy in HO 2 , several pptv of IO could significantly reduce HO 2 mixing ratios and NO/NO 2 ratios.