气候变化领域集成服务门户(CCPortal): Investigation of Isoprene Dynamics During the Day-to-Night Transition Period

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DOI	10.1029/2020JD032784
	Investigation of Isoprene Dynamics During the Day-to-Night Transition Period
	Wei D.; Alwe H.D.; Millet D.B.; Kavassalis S.C.; Lew M.; Bottorff B.; Stevens P.S.; Steiner A.L.
发表日期	2020
ISSN	2169897X
卷号	125 期号:20
英文摘要	At the University of Michigan Biological Station during the 2016 AMOS field campaign, isoprene concentrations typically peak in the early afternoon (around 15:00 local time, LT) under well-mixed conditions. However, an end-of-day peak (around 21:00 LT) occurs on 23% of the campaign days, followed by a rapid removal (from 21:00–22:00 LT) at rate of 0.57 hr−1 during the day-to-night transition period. During the end-of-day peak, in-canopy isoprene concentrations increase by 77% (from 3.5 to 6.2 ppbv) on average. Stratification and weak winds (<3.4 m s−1 at 46 m) significantly suppress turbulent exchanges between in- and above-canopy, leading to accumulation of isoprene emitted at dusk. A critical standard deviation of the vertical velocity (σw) of 0.14, 0.2, and 0.29 m s−1 is identified to detect the end-of-day peak for the height of 13, 21, and 34 m, respectively. In 85% of the end-of-day cases, the wind speed increases above 2.5 m s−1 after the peak along with a shift in wind direction, and turbulence is reestablished. Therefore, the wind speed of 2.5 m s−1 is considered as the threshold point where turbulence switches from being independent of wind speed to dependent on wind speed. The reinstated turbulence accounts for 80% of the subsequent isoprene removal with the remaining 20% explained by chemical reactions with hydroxyl radicals, ozone, and nitrate radicals. Observed isoprene fluxes do not support the argument that the end-of-day peak is reduced by vertical turbulent mixing, and we hypothesize that horizontal advection may play a role. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	forest canopy; isoprene; isoprene-OH chemistry; transition period; turbulent mixing
语种	英语
来源期刊	Journal of Geophysical Research: Atmospheres
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/185701
作者单位	Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, United States; Department of Soil, Water and Climate, University of Minnesota, Twin Cities, St. Paul, MN, United States; Department of Chemistry, University of Toronto, Toronto, ON, Canada; Department of Chemistry, Indiana University, Bloomington, IN, United States; School of Public and Environmental Affairs, Indiana University, Bloomington, IN, United States
推荐引用方式 GB/T 7714	Wei D.,Alwe H.D.,Millet D.B.,et al. Investigation of Isoprene Dynamics During the Day-to-Night Transition Period[J],2020,125(20).
APA	Wei D..,Alwe H.D..,Millet D.B..,Kavassalis S.C..,Lew M..,...&Steiner A.L..(2020).Investigation of Isoprene Dynamics During the Day-to-Night Transition Period.Journal of Geophysical Research: Atmospheres,125(20).
MLA	Wei D.,et al."Investigation of Isoprene Dynamics During the Day-to-Night Transition Period".Journal of Geophysical Research: Atmospheres 125.20(2020).