Open AccessBehavior of OH and HO 2 radicals during the Observations at a Remote Island of Okinawa (ORION99) field campaign: 1. Observation using a laser‐induced fluorescence instrument
Author(s) -
Kanaya Yugo,
Sadanaga Yasuhiro,
Nakamura Kenji,
Akimoto Hajime
Publication year - 2001
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000jd000178
Subject(s) - daytime , radical , troposphere , hydroperoxyl , lidar , environmental science , atmospheric sciences , analytical chemistry (journal) , hydroxyl radical , meteorology , chemistry , remote sensing , geology , physics , environmental chemistry , organic chemistry
The hydroxyl (OH) and hydroperoxyl (HO 2 ) radicals were measured by a laser‐induced fluorescence instrument at Cape Hedo, Okinawa Island, Japan, in summer 1999 during the Observations at a Remote Island of Okinawa (ORION99) field campaign. The field deployment of the instrument and its calibrations are described in detail. From the frequent calibrations during the field campaign, it was shown that the instrument, utilizing an optical fiber to transmit the laser light to the detection cell located on a tower, had a sufficiently stable sensitivity to OH and HO 2 in order to trace their diurnal and day‐to‐day variations. The detection limit of the instrument was typically around 4 × 10 6 radicals cm −3 with an integration time of 1 min. We could not examine fast OH variations. However, hourly averaged OH concentrations during daytime were statistically significant. The HO 2 concentrations were higher and the detailed variations were detected. On average, OH and HO 2 showed daytime maxima of around 4 × 10 6 radicals cm −3 and of around 17 pptv, respectively. The median, tenth, and ninetieth percentiles of the measured daytime HO 2 /OH concentration ratio were 76, 32, and 143, respectively. The power law dependence of HO 2 on J (O 1 D ) was about 0.5 when the NO concentration was lower than 300 pptv and was about 1 when the NO concentration was higher than 1 ppbv, which was consistent with the known radical chemistry in the lower troposphere.