• Open Access

Heterogeneous formation of nitryl chloride and its role as a nocturnal NOx reservoir species during CalNex-LA 2010

Authors

  • L. H. Mielke,

    1. Department of Chemistry, University of Calgary, Calgary, Alberta, Canada
    2. Now at Department of Chemistry, University of Indianapolis, Indianapolis, Indiana, USA
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  • J. Stutz,

    1. Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, USA
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  • C. Tsai,

    1. Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, USA
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  • S. C. Hurlock,

    1. Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, USA
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  • J. M. Roberts,

    1. Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration, Boulder, Colorado, USA
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  • P. R. Veres,

    1. Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration, Boulder, Colorado, USA
    2. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
    3. Now at Max-Planck-Institut für atmosphärische Chemie, Mainz, Germany
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  • K. D. Froyd,

    1. Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration, Boulder, Colorado, USA
    2. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
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  • P. L. Hayes,

    1. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
    2. Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado, USA
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  • M. J. Cubison,

    1. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
    2. Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado, USA
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  • J. L. Jimenez,

    1. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
    2. Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado, USA
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  • R. A. Washenfelder,

    1. Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration, Boulder, Colorado, USA
    2. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
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  • C. J. Young,

    1. Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration, Boulder, Colorado, USA
    2. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
    3. Now at Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
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  • J. B. Gilman,

    1. Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration, Boulder, Colorado, USA
    2. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
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  • J. A. de Gouw,

    1. Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration, Boulder, Colorado, USA
    2. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
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  • J. H. Flynn,

    1. Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas, USA
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  • N. Grossberg,

    1. Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas, USA
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  • B. L. Lefer,

    1. Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas, USA
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  • J. Liu,

    1. School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
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  • R. J. Weber,

    1. School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
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  • H. D. Osthoff

    Corresponding author
    1. Department of Chemistry, University of Calgary, Calgary, Alberta, Canada
    • Corresponding author: H. D. Osthoff, Department of Chemistry, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada. (hosthoff@ucalgary.ca)

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Abstract

[1] The nocturnal conversion of dinitrogen pentoxide (N2O5) to nitryl chloride (ClNO2) on chloride-containing aerosol can be a regionally important NOx (= NO + NO2) recycling and halogen activation pathway that affects oxidant photochemistry the following day. Here we present a comprehensive measurement data set acquired at Pasadena, California, during the CalNex-LA campaign 2010 that included measurements of odd nitrogen and its major components (NOy = NOx + NO3 + 2N2O5 + ClNO2 + HNO3 + HONO + peroxyacyl, alkyl, and aerosol nitrates) and aerosol size distribution and composition. Nitryl chloride was present during every night of the study (median mixing ratio at sunrise 800 pptv) and was usually a more significant nocturnal NOx and odd oxygen (Ox = O3 + NO2 + 3N2O5 + ClNO2) reservoir species than N2O5 (whose concentrations were calculated from its equilibrium with NO2 and NO3). At sunrise, ClNO2 accounted for 21% of NOz (=NOy − NOx), 4% of NOy, and 2.5% of Ox, respectively (median values). Kinetic parameters for the N2O5 to ClNO2 conversion were estimated by relating ClNO2 concentrations to their time-integrated heterogeneous production from N2O5 and were highly variable between nights. Production of ClNO2 required conversion of N2O5 on submicron aerosol with average yield (φ) and N2O5 reactive uptake probability (γ) of γφ = 0.008 (maximum 0.04), scaled with submicron aerosol chloride content, and was suppressed by aerosol organic matter and liquid water content. Not all of the observed variability of ClNO2 production efficiency could be rationalized using current literature parameterizations.

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