Abstract
Airborne measurements of the hydroxyl radical were performed aboard the NASA P‐3B using the Selected Ion Chemical Ionization technique during the Pacific Exploratory Mission (PEM)‐Tropics B study. Typical midday boundary layer OH concentrations of 6–7 × 106 molecule cm−3 were observed in the vicinity of Christmas Island (0°‐3°N)) and 7–8 × 106 molecule cm−3 in the vicinity of Tahiti (17°‐22°S). Photochemical box model calculations of the concentration of OH ([OH]) throughout the entire mission yield generally good agreement (slope = 1.26) with a tendency for the model to slightly overestimate the measured OH. Boundary layer measurements of OH in an air mass containing low ozone concentrations (<5 ppbv) yielded a midday [OH] of ∼5×106 molecule cm−3, some 45% lower than 7×106 molecule cm−3 observed in air masses at the same latitude with more typical ozone concentrations (30–40 ppbv). Measurements performed under clouds yielded [OH] of ∼2.5×106 molecule cm−3, a value which is a factor of 2 lower when compared to data taken on either side of the cloud. This decrease corresponds to the decrease in j(O3) to produce O(1D).
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.