Observational constraints on glyoxal production from isoprene oxidation and its contribution to organic aerosol over the Southeast United States
Observational constraints on glyoxal production from isoprene oxidation and its contribution to organic aerosol over the Southeast United States
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DOI：
10.1002/2016jd025331
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发表时间：
2016-08-27
影响因子：
4.4
通讯作者：
Horowitz, Larry W.
中科院分区：
文献类型：
--
作者：
Li, Jingyi;Mao, Jingqiu;Horowitz, Larry W.
我们使用一个0-D光化学盒模型和一个3-D全球化学-气候模型，结合NOAA东南Nexus （SENEX）飞机活动的观测结果，来了解美国东南部乙二醛的来源和汇。箱形模型模拟表明，三种异戊二烯氧化机制（AM3ST、AM3B和Master Chemical Mechanism (MCM) v3.3.1）在乙二醛生成方面存在很大差异。然后将这些机制应用到三维全球化学-气候模型中。与野外观测结果的比较表明，AM3ST具有有效的反应吸收系数，能较好地再现乙二醛的平均垂直剖面。glyx的2 × 10（-3）和AM3B没有异质损失的乙二醛。这两种机制导致美国东南部夏季边界层乙二醛产生0 ~ 0.8 μ gm（-3）的二次有机气溶胶（SOA）。我们认为这是乙二醛对SOA贡献的下限，因为除异戊二烯外，乙二醛的其他来源不包括在我们的模型中。此外，我们发现AM3B对甲醛和乙二醛与甲醛的相关性（RGF = [GLYX]/[HCHO]）表现出更好的一致性，这是由于它抑制了d-异戊二烯过氧自由基。我们还发现MCM v3.3.1可能低估了异戊二烯氧化产生的乙二醛，部分原因是低估了异戊二烯环氧二醇（IEPOX）过氧自由基与HO2反应的产率。我们的工作强调，乙二醛的气相生产在量化其对SOA的贡献方面存在很大的不确定性。
We use a 0-D photochemical box model and a 3-D global chemistry-climate model, combined with observations from the NOAA Southeast Nexus (SENEX) aircraft campaign, to understand the sources and sinks of glyoxal over the Southeast United States. Box model simulations suggest a large difference in glyoxal production among three isoprene oxidation mechanisms (AM3ST, AM3B, and Master Chemical Mechanism (MCM) v3.3.1). These mechanisms are then implemented into a 3-D global chemistry-climate model. Comparison with field observations shows that the average vertical profile of glyoxal is best reproduced by AM3ST with an effective reactive uptake coefficient.glyx of 2 x 10(-3) and AM3B without heterogeneous loss of glyoxal. The two mechanisms lead to 0-0.8 mu gm(-3) secondary organic aerosol (SOA) from glyoxal in the boundary layer of the Southeast U.S. in summer. We consider this to be the lower limit for the contribution of glyoxal to SOA, as other sources of glyoxal other than isoprene are not included in our model. In addition, we find that AM3B shows better agreement on both formaldehyde and the correlation between glyoxal and formaldehyde (RGF = [GLYX]/[HCHO]), resulting from the suppression of d-isoprene peroxy radicals. We also find that MCM v3.3.1 may underestimate glyoxal production from isoprene oxidation, in part due to an underestimated yield from the reaction of isoprene epoxydiol (IEPOX) peroxy radicals with HO2. Our work highlights that the gas-phase production of glyoxal represents a large uncertainty in quantifying its contribution to SOA.