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Detailed Reference Information |
Dickerson, R.R., Rhoads, K.P., Carsey, T.P., Oltmans, S.J., Burrows, J.P. and Crutzen, P.J. (1999). Ozone in the remote marine boundary layer: A possible role for halogens. Journal of Geophysical Research 104: doi: 10.1029/1999JD900023. issn: 0148-0227. |
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On the spring 1995 cruise of the National Oceanic and Atmospheric Administration research vessel Malcolm Baldrige, we measured very large diurnal variations in ozone concentrations in the marine boundary layer. Average diurnal variations of about 32% of the mean were observed over the tropical Indian Ocean. We simulated these observations with the Model of Chemistry in Clouds and Aerosols, a photochemical box model with detailed aerosol chemistry. The model was constrained with photolysis rates, humidity, aerosol concentrations, NO, CO, and O3 specified by shipboard observations and ozonesondes. Conventional homogeneous chemistry, where ozone photolysis to O(1D) and HOx chemistry dominate ozone destruction, can account for a diurnal variation of only about 12%. On wet sea-salt aerosols (at humidities above the deliquescence point), absorption of HOBr leads to release of BrCl and Br2, which photolyze to produce Br atoms that may provide an additional photochemical ozone sink. After 8 days of simulation, these Br atoms reach a peak concentration of 1.2¿107 cm-3 at noon and destroy ozone through a catalytic cycle involving BrO and HOBr. Reactive Br lost to HBr can be absorbed into the aerosol phase and reactivated. The model predicts a diurnal variation in O3 of 22% with aerosol-derived Br reaction explaining much, but not all, of the observed photochemical loss. The lifetime of ozone under these conditions is short, about 2 days. These results indicate that halogens play an important role in oxidation processes and the ozone budget in parts of the remote marine boundary layer. ¿ 1999 American Geophysical Union |
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BACKGROUND DATA FILES |
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Abstract |
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Keywords
Atmospheric Composition and Structure, Aerosols and particles (0345, 4801), Atmospheric Composition and Structure, Constituent sources and sinks, Atmospheric Composition and Structure, Troposphere—composition and chemistry, Meteorology and Atmospheric Dynamics, Boundary layer processes, Atmospheric Composition and Structure, Cloud physics and chemistry, Meteorology and Atmospheric Dynamics, Polar meteorology, Meteorology and Atmospheric Dynamics, Precipitation |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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