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Ground and Airborne U.K. Measurements of Nitryl Chloride: An Investigation of the Role of Cl Atom Oxidation at Weybourne Atmospheric Observatory
Author(s) -
Bannan Thomas J.,
Bacak Asan,
Le Breton Michael,
Flynn Michael,
Ouyang Bin,
McLeod Matthew,
Jones Rod,
Malkin Tamsin L.,
Whalley Lisa K.,
Heard Dwayne E.,
Bandy Brian,
Khan M. Anwar H.,
Shallcross Dudley E.,
Percival Carl J.
Publication year - 2017
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2017jd026624
Subject(s) - chemistry , photodissociation , chlorine , chloride , chemical ionization , atmospheric chemistry , mass spectrometry , photochemistry , analytical chemistry (journal) , ionization , environmental chemistry , ozone , organic chemistry , ion , chromatography
Nitryl chloride (ClNO 2 ) 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 NO x concentrations, a type of location poorly studied for ClNO 2 production. Concentrations of ClNO 2 exceeded that of the limit of detection (0.8 ppt) on each night of the campaign, as did concentrations of N 2 O 5 , which was also measured simultaneously with the Cambridge Broadband Cavity Enhanced Absorption Spectrometer. A peak concentration of 65 ppt of ClNO 2 is reported here. Vertical profiles of ClNO 2 from early‐ to middle‐morning flights in close proximity to WAO are also reported, showing elevated concentrations at low altitude. The photolysis of observed ClNO 2 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 O 3 is compared. Cl atom oxidation was deemed generally insignificant at this time and location for total oxidation due to the much lower concentration of ClNO 2 observed, even following the night of greatest ClNO 2 production.