气候变化领域集成服务门户(CCPortal): Impacts of multi-layer overlap on contrail radiative forcing

CCPortal

DOI	10.5194/acp-21-1649-2021
	Impacts of multi-layer overlap on contrail radiative forcing
	Sanz-Morère I.; Eastham S.D.; Allroggen F.; Speth R.L.; Barrett S.R.H.
发表日期	2021
ISSN	1680-7316
起始页码	1649
结束页码	1681
卷号	21 期号:3
英文摘要	Condensation trails ("contrails") which form behind aircraft are estimated to cause on the order of 50 % of the total climate forcing of aviation, matching the total impact of all accumulated aviation-attributable CO2. The climate impacts of these contrails are highly uncertain, in part due to the effect of overlap between contrails and other cloud layers. Although literature estimates suggest that overlap could change even the sign of contrail radiative forcing (RF), the impacts of cloud contrail overlaps are not well understood, and the effect of contrail contrail overlap has never been quantified. In this study we develop and apply a new model of contrail radiative forcing which explicitly accounts for overlap between cloud layers. Assuming maximum possible overlap to provide an upper bound on impacts, cloud contrail overlap is found to reduce the shortwave-cooling effect attributable to aviation by 66 % while reducing the longwave-warming effect by only 37 %. Therefore, on average in 2015, cloud contrail overlap increased the net radiative forcing from contrails. We also quantify the sensitivity of contrail radiative forcing to cloud cover with respect to geographic location. Clouds significantly increase warming at high latitudes and over sea, transforming cooling contrails into warming ones in the North Atlantic corridor. Based on the same data, our results indicate that disregarding overlap between a given pair of contrail layers can result in longwave and shortwave radiative forcing being overestimated by up to 16 % and 25 %, respectively, with the highest bias observed at high optical depths (> 0.4) and high solar zenith angles (> 75°). When applied to estimated global contrail coverage data for 2015, contrail contrail overlap reduces both the longwave and shortwave forcing by ∼ 2 % relative to calculations which ignore overlap. The effect is greater for longwave radiation, resulting in a 3 % net reduction in the estimated RF when overlap is correctly accounted for. This suggests that contrail contrail overlap radiative effects can likely be neglected in estimates of the current-day environmental impacts of aviation. However, the effect of contrail contrail overlap may increase in the future as the airline industry grows into new regions. © 2021 Author(s).
语种	英语
scopus关键词	climate effect; cloud cover; condensation; contrail; cooling; radiative forcing; warming; Atlantic Ocean; Atlantic Ocean (North)
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/247171
作者单位	Laboratory for Aviation and the Environment, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Joint Program on the Science and Policy of Global Change, Massachusetts Institute of Technology, Cambridge, MA, United States
推荐引用方式 GB/T 7714	Sanz-Morère I.,Eastham S.D.,Allroggen F.,et al. Impacts of multi-layer overlap on contrail radiative forcing[J],2021,21(3).
APA	Sanz-Morère I.,Eastham S.D.,Allroggen F.,Speth R.L.,&Barrett S.R.H..(2021).Impacts of multi-layer overlap on contrail radiative forcing.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(3).
MLA	Sanz-Morère I.,et al."Impacts of multi-layer overlap on contrail radiative forcing".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.3(2021).