Observational Constraints on the Oxidation of NOx in the Upper Troposphere

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• 作者：Benjamin. A. Nault ; Charity Garland ; Paul J. Wooldridge ; William H. Brune ; Pedro Campuzano-Jost ; John D. Crounse ; Douglas A. Day ; Jack Dibb ; Samuel R. Hall ; L. Gregory Huey ; José L. Jimenez ; Xiaoxi Liu ; Jingqiu Mao ; Tomas Mikoviny ; Jeff Peischl ; Ilana B. Pollack ; Xinrong Ren ; Thomas B. Ryerson ; Eric Scheuer ; Kirk Ullmann ; Paul O. Wennberg ; Armin Wisthaler ; Li Zhang ; Ronald C. Cohen
• 刊名：Journal of Physical Chemistry A
• 出版年：2016
• 出版时间：March 10, 2016
• 年：2016
• 卷：120
• 期：9
• 页码：1468-1478
• 全文大小：618K
• ISSN：1520-5215

文摘

NOb>xb> (NOb>xb> ≡ NO + NOb>2b>) regulates Ob>3b> and HOb>xb> (HOb>xb> ≡ OH + HOb>2b>) concentrations in the upper troposphere. In the laboratory, it is difficult to measure rates and branching ratios of the chemical reactions affecting NOb>xb> at the low temperatures and pressures characteristic of the upper troposphere, making direct measurements in the atmosphere especially useful. We report quasi-Lagrangian observations of the chemical evolution of an air parcel following a lightning event that results in high NOb>xb> concentrations. These quasi-Lagrangian measurements obtained during the Deep Convective Clouds and Chemistry experiment are used to characterize the daytime rates for conversion of NOb>xb> to different peroxy nitrates, the sum of alkyl and multifunctional nitrates, and HNOb>3b>. We infer the following production rate constants [in (cm³/molecule)/s] at 225 K and 230 hPa: 7.2(±5.7) × 10^–12 (CHb>3b>Ob>2b>NOb>2b>), 5.1(±3.1) × 10^–13 (HOb>2b>NOb>2b>), 1.3(±0.8) × 10^–11 (PAN), 7.3(±3.4) × 10^–12 (PPN), and 6.2(±2.9) × 10^–12 (HNOb>3b>). The HNOb>3b> and HOb>2b>NOb>2b> rates are ∼30–50% lower than currently recommended whereas the other rates are consistent with current recommendations to within ±30%. The analysis indicates that HNOb>3b> production from the HOb>2b> and NO reaction (if any) must be accompanied by a slower rate for the reaction of OH with NOb>2b>, keeping the total combined rate for the two processes at the rate reported for HNOb>3b> production above.