气候变化领域集成服务门户(CCPortal): Disentangling the impact of air-sea interaction and boundary layer cloud formation on stable water isotope signals in the warm sector of a Southern Ocean cyclone

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DOI	10.5194/acp-22-10353-2022
	Disentangling the impact of air-sea interaction and boundary layer cloud formation on stable water isotope signals in the warm sector of a Southern Ocean cyclone
	Thurnherr, Iris; Aemisegger, Franziska
发表日期	2022
ISSN	1680-7316
EISSN	1680-7324
起始页码	10353
结束页码	10373
卷号	22 期号:15 页码:21
英文摘要	Stable water isotopes in marine boundary layer water vapour are strongly influenced by the strength of air-sea fluxes. Air-sea fluxes in the extratropics are modulated by the large-scale atmospheric flow, for instance by the advection of warm and moist air masses in the warm sector of extratropical cyclones. A distinct isotopic composition of the water vapour in the latter environment has been observed over the Southern Ocean during the 2016/2017 Antarctic Circumnavigation Expedition (ACE). Most prominently, the secondary isotope variable deuterium excess (d =delta H-2-8 center dot delta O-18) shows negative values in the cyclones' warm sector. In this study, three mechanisms are proposed and evaluated to explain these observed negative d values. We present three single-process air parcel models, which simulate the evolution of delta H-2, delta O-18, d and specific humidity in an air parcel induced by decreasing ocean evaporation, dew deposition and upstream cloud formation. Simulations with the isotope-enabled numerical weather prediction model COSMOiso, which have previously been validated using observations from the ACE campaign, are used to (i) validate the air parcel models, (ii) quantify the relevance of the three processes for stable water isotopes in the warm sector of the investigated extratropical cyclone and (iii) study the extent of non-linear interactions between the different processes. This analysis shows that we are able to simulate the evolution of d during the air parcel's transport in a realistic way with the mechanistic approach of using single-process air parcel models. Most importantly, we find that decreasing ocean evaporation and dew deposition lead to the strongest d decrease in near-surface water vapour in the warm sector and that upstream cloud formation plays a minor role. By analysing COSMOiso backward trajectories we show that the persistent low d values observed in the warm sector of extratropical cyclones are not a result of material conservation of low d. Instead, the latter Eulerian feature is sustained by the continuous production of low d values due to air-sea interactions in new air parcels entering the warm sector. These results improve our understanding of the relative importance of air-sea interaction and boundary layer cloud formation on the stable water isotope variability of near-surface marine boundary layer water vapour. To elucidate the role of hydrometeor-vapour interactions for the stable water isotope variability in the upper parts of the marine boundary layer, future studies should focus on high-resolution vertical isotope profiles.
学科领域	Environmental Sciences; Meteorology & Atmospheric Sciences
语种	英语
WOS研究方向	Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences
WOS记录号	WOS:000839609800001
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/273147
作者单位	Swiss Federal Institutes of Technology Domain; ETH Zurich; University of Bergen; Bjerknes Centre for Climate Research
推荐引用方式 GB/T 7714	Thurnherr, Iris,Aemisegger, Franziska. Disentangling the impact of air-sea interaction and boundary layer cloud formation on stable water isotope signals in the warm sector of a Southern Ocean cyclone[J],2022,22(15):21.
APA	Thurnherr, Iris,&Aemisegger, Franziska.(2022).Disentangling the impact of air-sea interaction and boundary layer cloud formation on stable water isotope signals in the warm sector of a Southern Ocean cyclone.ATMOSPHERIC CHEMISTRY AND PHYSICS,22(15),21.
MLA	Thurnherr, Iris,et al."Disentangling the impact of air-sea interaction and boundary layer cloud formation on stable water isotope signals in the warm sector of a Southern Ocean cyclone".ATMOSPHERIC CHEMISTRY AND PHYSICS 22.15(2022):21.