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Joel Thornton and Theran Riedel Department of Atmospheric Sciences Department of Chemistry

Chlorine Radical Sources in the Polluted Marine Boundary Layer: Insights from in situ measurements of ClNO 2 and Cl 2. Joel Thornton and Theran Riedel Department of Atmospheric Sciences Department of Chemistry University of Washington Seattle, WA. Atomic Chlorine.

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Joel Thornton and Theran Riedel Department of Atmospheric Sciences Department of Chemistry

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  1. Chlorine Radical Sources in the Polluted Marine Boundary Layer: Insights from in situ measurements of ClNO2 and Cl2 Joel Thornton and Theran Riedel Department of Atmospheric Sciences Department of Chemistry University of Washington Seattle, WA

  2. Atomic Chlorine • Atomic Cl has a large oxidizing potential (10-100x OH) • Cl atoms have potential to substantially affect O3, VOC, and Hg levels. • Cl atom sources are uncertain, but Cl2 has typically been considered the major Cl atom source in polluted regions • Pechtl and von Glasow. GRL, 2007 • Knipping and Dabdub. ES&T, 2003 • Spicer et al. Nature 394, 1998.

  3. Atomic chlorine production ? HOCl H+, Cl- Cl2 ClNO2 Cl- OH N2O5 Cl HCl BrCl H+, Cl- HOBr

  4. Expected ClNO2 production ClNO2 Production: log(g Cl/year) From: Thornton, et al. Nature 464, 2010

  5. CalNex observations Los Angeles, CA ClNO2 pptv

  6. Expected Cl2 levels • Spicer et al. at Long Island, NY, June 1996. • Finley and Saltzman at La Jolla, CA, January 2006. From: Spicer et al. Nature 394, 1998. AND Finley and Saltzman. JGR 113, 2008.

  7. CalNex observations

  8. Inland production and plume transport/interception? Santa Monica Bay

  9. ClNO2 and Cl2 correlations UTC DOY

  10. Cl atom production: ClNO2 vs. Cl2

  11. Thoughts • Our observations consistent with substantial inland production of Cl atom precursors transported to marine environments along with continued production off shore. • ClNO2 should be considered a Cl atom precursor with at least similar importance to Cl2. • Measurements of N2O5 and aerosol composition, mixing, play important roles given the heterogeneous reaction mechanism at work.

  12. Opportunities for Collaboration & Future Analyses • ClNO2 production efficiencies • ClNO2 yield predictions • Utilize HCl measurements • Hydrocarbon evidence of Cl atom chemistry • Utilize PTRMS and GC-FID VOC data • ClNO2 as a fraction of NOy • Box modeling Cl activation and Cl atom chemistry

  13. The End Funding: NASA NESSF NNX-10AN48H,

  14. ClNO2 as a fraction of NOy

  15. Finley and Satlzman. JGR 113, 2008

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