气候变化领域集成服务门户(CCPortal): Tropospheric Age-of-Air: Influence of SF6 Emissions on Recent Surface Trends and Model Biases

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DOI	10.1029/2021JD035451
	Tropospheric Age-of-Air: Influence of SF6 Emissions on Recent Surface Trends and Model Biases
	Orbe C.; Waugh D.W.; Montzka S.; Dlugokencky E.J.; Strahan S.; Steenrod S.D.; Strode S.; Elkins J.W.; Hall B.; Sweeney C.; Hintsa E.J.; Moore F.L.; Penafiel E.
发表日期	2021
ISSN	2169-897X
卷号	126 期号:19
英文摘要	The mean age since air was last at the Northern Hemisphere (NH) midlatitude surface is a fundamental property of tropospheric transport. Here we approximate the mean age in terms of an (Formula presented.) age” ((Formula presented.)), derived from surface and aircraft measurements of (Formula presented.) that are broader in spatial scope and cover a longer time period (1997–2018) than considered previously. At the surface, (Formula presented.) increases from near-zero values north of (Formula presented.) N to (Formula presented.) 1.5 years over the Southern Hemisphere (SH) extratropics, with the largest meridional gradients occurring in the tropics. By comparison, vertical gradients in (Formula presented.) are weak throughout, with only slight increases/decreases with height in the NH/SH. The broader spatial coverage of the measurements reveals strong variations in the seasonal cycle of (Formula presented.) within the (sub)tropics that are weaker over the Atlantic and Pacific oceans, compared to over the Indian Ocean. Observations from 2000 to 2018 reveal that the (Formula presented.) age at sites in the SH has been decreasing by (Formula presented.) 0.12 years/dec. However, this decrease is not due to changes in transport but, rather, is likely related to changes in emissions, which have increased globally and reportedly shifted from northern midlatitudes into the subtropics. Simulations, which reproduce the (Formula presented.) age trends, show no decreases in an age-of-air tracer, reinforcing the fact that (Formula presented.) represents only an approximation to the mean age. Finally, the modeled (Formula presented.) ages are older than observed, by (Formula presented.) 0.3–0.4 years throughout the southern extratropics. We show that this bias is partly related to an overestimation in simulated (Formula presented.) near emissions regions, likely reflecting a combination of uncertainties in emissions and model transport. © 2021 American Geophysical Union. All Rights Reserved. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
英文关键词	atmospheric transport; interhemispheric exchange; SF6 emissions; tracers
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/236979
作者单位	NASA Goddard Institute for Space Studies, New York, NY, United States; Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD, United States; Global Monitoring Laboratory, NOAA, Boulder, CO, United States; Universities Space Research Association, Columbia, MD, United States; NASA Goddard Space Flight Center, Atmospheric Chemistry and Dynamics Laboratory, Greenbelt, MD, United States; Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder, Boulder, CO, United States
推荐引用方式 GB/T 7714	Orbe C.,Waugh D.W.,Montzka S.,et al. Tropospheric Age-of-Air: Influence of SF6 Emissions on Recent Surface Trends and Model Biases[J],2021,126(19).
APA	Orbe C..,Waugh D.W..,Montzka S..,Dlugokencky E.J..,Strahan S..,...&Penafiel E..(2021).Tropospheric Age-of-Air: Influence of SF6 Emissions on Recent Surface Trends and Model Biases.Journal of Geophysical Research: Atmospheres,126(19).
MLA	Orbe C.,et al."Tropospheric Age-of-Air: Influence of SF6 Emissions on Recent Surface Trends and Model Biases".Journal of Geophysical Research: Atmospheres 126.19(2021).