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|a Dusanter, S.
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|a Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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|a Molina, Luisa Tan
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|a Molina, Luisa Tan
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|a Sheehy, P.
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|a Vimal, D.
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|a Stevens, P. S.
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|a Volkamer, R.
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|a Molina, Luisa Tan
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|a Baker, A.
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|a Meinardi, S.
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|a Blake, D.
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|a Sheehy, P.
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|a Merten, A.
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|a Zhang, R.
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|a Zheng, J.
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|a Fortner, E. C.
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|a Junkermann, W.
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|a Dubey, Madan
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|a Rahn, T.
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|a Eichinger, B.
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|a Lewandowski, P.
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|a Prueger, J.
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|a Holder, H.
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|a Measurements of OH and HO2 concentrations during the MCMA-2006 field campaign - Part 2: Model comparison and radical budget
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|b Copernicus Publications on behalf of the European Geosciences Union,
|c 2012-01-03T20:55:05Z.
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|z Get fulltext
|u http://hdl.handle.net/1721.1/67896
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|a Measurements of hydroxyl (OH) and hydroperoxy (HO2) radicals were made during the Mexico City Metropolitan Area (MCMA) field campaign as part of the MILAGRO (Megacity Initiative: Local and Global Research Observations) project during March 2006. These measurements provide a unique opportunity to test current models of atmospheric ROx (OH + HO2 + RO2) photochemistry under polluted conditions. A zero-dimensional box model based on the Regional Atmospheric Chemical Mechanism (RACM) was constrained by 10-min averages of 24 J-values and the concentrations of 97 chemical species. Several issues related to the ROx chemistry under polluted conditions are highlighted in this study: (i) Measured concentrations of both OH and HO2 were underpredicted during morning hours on a median campaign basis, suggesting a significant source of radicals is missing from current atmospheric models under polluted conditions, consistent with previous urban field campaigns. (ii) The model-predicted HO2/OH ratios underestimate the measurements for NO mixing ratios higher than 5 ppb, also consistent with previous urban field campaigns. This suggests that under high NOx conditions, the HO2 to OH propagation rate may be overestimated by the model or a process converting OH into HO2 may be missing from the chemical mechanism. On a daily basis (08:40 a.m.-06:40 p.m.), an analysis of the radical budget indicates that HONO photolysis, HCHO photolysis, O3-alkene reactions and dicarbonyls photolysis are the main radical sources. O3 photolysis contributes to less than 6% of the total radical production.
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|a Henry & Camille Dreyfus Foundation
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|a National Science Foundation (U.S.) (ATM-9984152)
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|a National Science Foundation (U.S.) (0612738)
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|a en_US
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|a Article
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|t Atmospheric Chemistry and Physics
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