气候变化领域集成服务门户(CCPortal): The importance of North Atlantic Ocean transports for seasonal forecasts

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DOI	10.1007/s00382-020-05364-6
	The importance of North Atlantic Ocean transports for seasonal forecasts
	Tietsche S.; Balmaseda M.; Zuo H.; Roberts C.; Mayer M.; Ferranti L.
发表日期	2020
ISSN	0930-7575
起始页码	1995
结束页码	2011
卷号	55
英文摘要	The Atlantic Meridional Overturning Circulation (AMOC) is a main driver for predictability at decadal time scales, but has been largely ignored in the context of seasonal forecasts. Here, we show compelling evidence that AMOC initialization can have a direct and strong impact on seasonal forecasts. Winter reforecasts with SEAS5, the current operational seasonal forecasting system by the European Centre for Medium-Range Weather Forecasts, exhibit errors of sea-surface temperature (SST) in the western part of the North Atlantic Subpolar Gyre that are strongly correlated with decadal variations in the AMOC initial conditions. In the early reforecast period 1981–1996, too warm SST coincide with an overly strong AMOC transporting excessive heat into the region. In the ocean reanalyses providing the forecast initial conditions, excessive heat transport is balanced by additional surface cooling from relaxing towards observed SST, and therefore the fit to observations is acceptable. However, the additional surface cooling contributes to enhanced deep convection and strengthens the AMOC, thereby establishing a feedback loop. In the forecasts, where the SST relaxation is absent, the balance is disrupted, and fast growth of SST errors ensues. The warm SST bias has a strong local impact on surface air temperature, mean sea-level pressure, and precipitation patterns, but remote impact is small. In the late reforecast period 2001–2016, neither the SST in the western North Atlantic nor the AMOC show large biases. The non-stationarity of the bias prevents an effective forecast calibration and causes an apparent loss of skill in the affected region. The case presented here demonstrates the importance of correctly initializing slowly varying aspects of the Earth System such as the AMOC in order to improve forecasts on seasonal and shorter time scales. © 2020, The Author(s).
英文关键词	AMOC; ocean reanalysis; Seasonal forecasts
语种	英语
scopus关键词	atmospheric transport; decadal variation; meridional circulation; sea surface temperature; seasonality; weather forecasting; 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/145323
作者单位	ECMWF, Shinfield Park, Reading, RG2 9AX, United Kingdom
推荐引用方式 GB/T 7714	Tietsche S.,Balmaseda M.,Zuo H.,et al. The importance of North Atlantic Ocean transports for seasonal forecasts[J],2020,55.
APA	Tietsche S.,Balmaseda M.,Zuo H.,Roberts C.,Mayer M.,&Ferranti L..(2020).The importance of North Atlantic Ocean transports for seasonal forecasts.Climate Dynamics,55.
MLA	Tietsche S.,et al."The importance of North Atlantic Ocean transports for seasonal forecasts".Climate Dynamics 55(2020).