Ground and Airborne U.K. Measurements of Nitryl Chloride: An Investigation of the Role of Cl Atom Oxidation at Weybourne Atmospheric Observatory

Thomas J. Bannan*, Asan Bacak, Michael Le Breton, Michael Flynn, Bin Ouyang, Matthew Mcleod, Rod Jones, Tamsin L. Malkin, Lisa K. Whalley, Dwayne E. Heard, Brian Bandy, M. Anwar H. Khan, Dudley E. Shallcross, Carl J. Percival

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Nitryl chloride (ClNO2) measurements from the Weybourne Atmospheric Observatory (WAO) are reported from March to April 2013 using a quadruple chemical ionization mass spectrometer with the I- ionization scheme. WAO is a rural coastal site with generally low NOx concentrations, a type of location poorly studied for ClNO2 production. Concentrations of ClNO2 exceeded that of the limit of detection (0.8 ppt) on each night of the campaign, as did concentrations of N2O5, which was also measured simultaneously with the Cambridge Broadband Cavity Enhanced Absorption Spectrometer. A peak concentration of 65 ppt of ClNO2 is reported here. Vertical profiles of ClNO2 from early- to middle-morning flights in close proximity to WAO are also reported, showing elevated concentrations at low altitude. The photolysis of observed ClNO2 and a box model utilizing the Master Chemical Mechanism modified to include chlorine chemistry was used to calculate Cl atom concentrations. This model utilized numerous VOCs from the second Tropospheric Organic Chemistry project in 2004, at the same location and time of year. From this the relative importance of the oxidation of three groups of measured VOCs (alkanes, alkenes, and alkynes) by OH radicals, Cl atoms, and O3 is compared. Cl atom oxidation was deemed generally insignificant at this time and location for total oxidation due to the much lower concentration of ClNO2 observed, even following the night of greatest ClNO2 production.

    Original languageEnglish
    Pages (from-to)11154-11165
    Number of pages11
    JournalJournal of Geophysical Research: Atmospheres
    Volume122
    Issue number20
    Early online date19 Oct 2017
    DOIs
    Publication statusPublished - 15 Nov 2017

    Keywords

    • Halogen chemistry
    • Tropospheric oxidation

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