气候变化领域集成服务门户(CCPortal): How Gulf-Stream SST-fronts influence Atlantic winter storms: Results from a downscaling experiment with HARMONIE to the role of modified latent heat fluxes and low-level baroclinicity

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DOI	10.1007/s00382-018-4486-7
	How Gulf-Stream SST-fronts influence Atlantic winter storms: Results from a downscaling experiment with HARMONIE to the role of modified latent heat fluxes and low-level baroclinicity
	Vries H.; Scher S.; Haarsma R.; Drijfhout S.; Delden A.
发表日期	2019
ISSN	0930-7575
起始页码	5899
结束页码	5909
卷号	52 期号:2020-09-10
英文摘要	The strong horizontal gradients in sea surface temperature (SST) of the Atlantic Gulf Stream exert a detectable influence on extratropical cyclones propagating across the region. This is shown in a sensitivity experiment where 24 winter storms taken from ERA-Interim are simulated with HARMONIE at 10-km resolution. Each storm is simulated twice. First, using observed SST (REF). In the second simulation a smoothed SST is offered (SMTH), while lateral and upper-level boundary conditions are unmodified. Each storm pair propagates approximately along the same track, however their intensities (as measured by maximal near-surface wind speed or 850-hPa relative vorticity) differ up to ± 25%. A 30-member ensemble created for one of the storms shows that on a single-storm level the response is systematic rather than random. To explain the broad response in storm strength, we show that the SST-adjustment modifies two environmental parameters: surface latent heat flux (LHF) and low-level baroclinicity (B). LHF influences storms by modifying diabatic heating and boundary-layer processes such as vertical mixing. The position of each storm’s track relative to the SST-front is important. South of the SST-front the smoothing leads to lower SST, reduced LHF and storms with generally weaker maximum near-surface winds. North of the SST-front the increased LHF tend to enhance the winds, but the accompanying changes in baroclinicity are not necessarily favourable. Together these mechanisms explain up to 80% of the variability in the near-surface maximal wind speed change. Because the mechanisms are less effective in explaining more dynamics-oriented indicators like 850 hPa relative vorticity, we hypothesise that part of the wind-speed change is related to adjustment of the boundary-layer processes in response to the LHF and B changes. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
英文关键词	Atlantic winter storms; Gulf Stream; SST-fronts
语种	英语
scopus关键词	atmospheric front; baroclinic mode; boundary layer; downscaling; ensemble forecasting; experimental study; latent heat flux; sea surface temperature; storm; vertical mixing; winter; Atlantic Ocean; Gulf Stream
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/146320
作者单位	Royal Netherlands Meteorological Institute, De Bilt, Netherlands; Meteorological Institute and Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden; University of Southampton, Southampton, United Kingdom; IMAU, Utrecht University, Utrecht, Netherlands
推荐引用方式 GB/T 7714	Vries H.,Scher S.,Haarsma R.,et al. How Gulf-Stream SST-fronts influence Atlantic winter storms: Results from a downscaling experiment with HARMONIE to the role of modified latent heat fluxes and low-level baroclinicity[J],2019,52(2020-09-10).
APA	Vries H.,Scher S.,Haarsma R.,Drijfhout S.,&Delden A..(2019).How Gulf-Stream SST-fronts influence Atlantic winter storms: Results from a downscaling experiment with HARMONIE to the role of modified latent heat fluxes and low-level baroclinicity.Climate Dynamics,52(2020-09-10).
MLA	Vries H.,et al."How Gulf-Stream SST-fronts influence Atlantic winter storms: Results from a downscaling experiment with HARMONIE to the role of modified latent heat fluxes and low-level baroclinicity".Climate Dynamics 52.2020-09-10(2019).