气候变化领域集成服务门户(CCPortal): AMOC sensitivity to surface buoyancy fluxes: the role of air-sea feedback mechanisms

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DOI	10.1007/s00382-019-04802-4
	AMOC sensitivity to surface buoyancy fluxes: the role of air-sea feedback mechanisms
	Kostov Y.; Johnson H.L.; Marshall D.P.
发表日期	2019
ISSN	0930-7575
起始页码	4521
结束页码	4537
卷号	53 期号:2020-07-08
英文摘要	We interrogate the sensitivity of the Atlantic Meridional Overturning Circulation (AMOC) to surface heat and freshwater fluxes over the Subpolar Gyre in an ocean general circulation model and its adjoint. Surface heat loss out of the Subpolar Gyre in the winter strengthens the AMOC at a lead time of approximately 6 months. However, the same surface heat flux anomaly in the summer leads to a delayed AMOC weakening that emerges at a lag of 8 months. Under a summer surface cooling perturbation, the AMOC progressively weakens up to a lag of approximately 80 months, and then the negative overturning anomaly persists for years. Compared with the sensitivity to surface heat fluxes, seasonality in the AMOC sensitivity to surface freshwater fluxes is less pronounced, and there is no sign reversal between the response to summer and winter perturbations. We explain the mechanisms behind the large seasonal differences in the AMOC sensitivity to surface heat fluxes and highlight the role of evaporation. Heat flux anomalies over the Subpolar Gyre trigger changes in the rate of evaporation and hence affect the salinity of the mixed layer. Surface cooling gives rise to freshening in the following months, whereas warming leads to salinification. Persistent buoyancy changes due to salinity responses counteract the impact of heat fluxes to a varying extent depending on the seasonal mixed layer depth. On the other hand, air-sea feedback mechanisms exert a positive feedback on the AMOC response to surface freshwater flux perturbations both in the summer and in the winter months. © 2019, The Author(s).
英文关键词	Meridional overturning circulation; Mixed layer; North Atlantic; Seasonality; Sensitivity; Surface freshwater flux; Surface heat flux
语种	英语
scopus关键词	atmosphere-ocean coupling; buoyancy; feedback mechanism; freshwater; heat flux; meridional circulation; mixed layer; seasonality; sensitivity analysis; surface flux; Atlantic Ocean; Atlantic Ocean (North)
来源期刊	Climate Dynamics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/145960
作者单位	Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom; Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, United Kingdom
推荐引用方式 GB/T 7714	Kostov Y.,Johnson H.L.,Marshall D.P.. AMOC sensitivity to surface buoyancy fluxes: the role of air-sea feedback mechanisms[J],2019,53(2020-07-08).
APA	Kostov Y.,Johnson H.L.,&Marshall D.P..(2019).AMOC sensitivity to surface buoyancy fluxes: the role of air-sea feedback mechanisms.Climate Dynamics,53(2020-07-08).
MLA	Kostov Y.,et al."AMOC sensitivity to surface buoyancy fluxes: the role of air-sea feedback mechanisms".Climate Dynamics 53.2020-07-08(2019).