气候变化领域集成服务门户(CCPortal): Constraining remote oxidation capacity with ATom observations

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DOI	10.5194/acp-20-7753-2020
	Constraining remote oxidation capacity with ATom observations
	Travis K.R.; Heald C.L.; Allen H.M.; Apel E.C.; Arnold S.R.; Blake D.R.; Brune W.H.; Chen X.; Commane R.; Crounse J.D.; Daube B.C.; Diskin G.S.; Elkins J.W.; Evans M.J.; Hall S.R.; Hintsa E.J.; Hornbrook R.S.; Kasibhatla P.S.; Kim M.J.; Luo G.; McKain K.; Millet D.B.; Moore F.L.; Peischl J.; Ryerson T.B.; Sherwen T.; Thames A.B.; Ullmann K.; Wang X.; Wennberg P.O.; Wolfe G.M.; Yu F.
发表日期	2020
ISSN	1680-7316
起始页码	7753
结束页码	7781
卷号	20 期号:13
英文摘要	The global oxidation capacity, defined as the tropospheric mean concentration of the hydroxyl radical (OH), controls the lifetime of reactive trace gases in the atmosphere such as methane and carbon monoxide (CO). Models tend to underestimate the methane lifetime and CO concentrations throughout the troposphere, which is consistent with excessive OH. Approximately half of the oxidation of methane and non-methane volatile organic compounds (VOCs) is thought to occur over the oceans where oxidant chemistry has received little validation due to a lack of observational constraints. We use observations from the first two deployments of the NASA ATom aircraft campaign during July-August 2016 and January-February 2017 to evaluate the oxidation capacity over the remote oceans and its representation by the GEOS-Chem chemical transport model. The model successfully simulates the magnitude and vertical profile of remote OH within the measurement uncertainties. Comparisons against the drivers of OH production (water vapor, ozone, and NOy concentrations, ozone photolysis frequencies) also show minimal bias, with the exception of wintertime NOy. The severe model overestimate of NOy during this period may indicate insufficient wet scavenging and/or missing loss on sea-salt aerosols. Large uncertainties in these processes require further study to improve simulated NOy partitioning and removal in the troposphere, but preliminary tests suggest that their overall impact could marginally reduce the model bias in tropospheric OH. During the ATom-1 deployment, OH reactivity (OHR) below 3 km is significantly enhanced, and this is not captured by the sum of its measured components (cOHRobs) or by the model (cOHRmod). This enhancement could suggest missing reactive VOCs but cannot be explained by a comprehensive simulation of both biotic and abiotic ocean sources of VOCs. Additional sources of VOC reactivity in this region are difficult to reconcile with the full suite of ATom measurement constraints. The model generally reproduces the magnitude and seasonality of cOHRobs but underestimates the contribution of oxygenated VOCs, mainly acetaldehyde, which is severely underestimated throughout the troposphere despite its calculated lifetime of less than a day. Missing model acetaldehyde in previous studies was attributed to measurement uncertainties that have been largely resolved. Observations of peroxyacetic acid (PAA) provide new support for remote levels of acetaldehyde. The underestimate in both model acetaldehyde and PAA is present throughout the year in both hemispheres and peaks during Northern Hemisphere summer. The addition of ocean sources of VOCs in the model increases cOHRmod by 3 % to 9 % and improves model-measurement agreement for acetaldehyde, particularly in winter, but cannot resolve the model summertime bias. Doing so would require 100 Tg yr-1 of a longlived unknown precursor throughout the year with significant additional emissions in the Northern Hemisphere summer. Improving the model bias for remote acetaldehyde and PAA is unlikely to fully resolve previously reported model global biases in OH and methane lifetime, suggesting that future work should examine the sources and sinks of OH over land. © Author(s) 2020.
语种	英语
scopus关键词	airborne survey; atmospheric chemistry; carbon monoxide; concentration (composition); hydroxyl radical; marine atmosphere; methane; modeling; oxidation; trace gas; troposphere; volatile organic compound
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/247674
作者单位	Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, United States; Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO, United States; Institute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, United Kingdom; Department of Chemistry, University of California Irvine, Irvine, CA, United States; Department of Meteorology, Pennsylvania State University, University Park, PA, United States; University of Minnesota, Department of Soil, Water and Climate, St. Paul, MN, United States; Dept. of Earth and Environ. Sciences of Lamont-Doherty Earth Observatory and Columbia University, Palisades, NY, United States; Divisio...
推荐引用方式 GB/T 7714	Travis K.R.,Heald C.L.,Allen H.M.,et al. Constraining remote oxidation capacity with ATom observations[J],2020,20(13).
APA	Travis K.R..,Heald C.L..,Allen H.M..,Apel E.C..,Arnold S.R..,...&Yu F..(2020).Constraining remote oxidation capacity with ATom observations.ATMOSPHERIC CHEMISTRY AND PHYSICS,20(13).
MLA	Travis K.R.,et al."Constraining remote oxidation capacity with ATom observations".ATMOSPHERIC CHEMISTRY AND PHYSICS 20.13(2020).