气候变化领域集成服务门户(CCPortal): Downstream development during South African cut-off low pressure systems

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DOI	10.1016/j.atmosres.2020.105315
	Downstream development during South African cut-off low pressure systems
	Ndarana T.; Rammopo T.S.; Bopape M.-J.; Reason C.J.C.; Chikoore H.
发表日期	2021
ISSN	0169-8095
卷号	249
英文摘要	Using 39 years of ECMWF renalysis data, an established energetics framework and simple composite analysis this study has shown that South African cut-off low (COL) pressure systems are preceded by downstream development of a baroclinic wave. Downstream development is characterised by the evolution of two energy centres, one located upstream in the midlatitudes and another downstream in the subtropics. The upstream eddy kinetic energy, which is associated with a midlatitude jet streak, develops and reaches its maximum before the formation of the closed COL cyclonic circulation. The downstream eddy kinetic energy centre maximises at the point where the closed circulation forms. The upstream eddy kinetic energy centre grows from baroclinic conversion from eddy available potential energy to eddy kinetic energy, whilst the downstream centre grows by receiving energy by means of ageostrophic geopotential fluxes that transport eddy kinetic energy in a north-eastward direction from the upstream centre. These ageostrophic geopotential fluxes are induced, increased in magnitude and directed by processes associated with Rossby wave breaking (RWB) on the midlatitude dynamical tropopause and so the downstream energy transfer connects South African COLs to midlatitude processes. The study has further shown that the baroclinic kinetic energy configuration previously associated with wet seasons over South Africa is consistent with times when COLs forms over the country. © 2020 Elsevier B.V.
英文关键词	Cut-off lows; Downstream development; Eddy kinetic energy
语种	英语
scopus关键词	Energy transfer; Kinetics; Mechanical waves; Potential energy; Baroclinic waves; Composite analysis; Cut-off low pressure; Cyclonic circulation; Downstream energy; Eddy kinetic energy; Energy configurations; Pressure system; Kinetic energy
来源期刊	Atmospheric Research
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/141640
作者单位	Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Hatfield, South Africa; Department of Research and Innovation, South African Weather Service, Centurion, South Africa; Department of Oceanography, University of Cape Town, Cape Town, South Africa; Unit for Environmental Sciences and Management, North-West University, Vanderbijlpark, South Africa
推荐引用方式 GB/T 7714	Ndarana T.,Rammopo T.S.,Bopape M.-J.,et al. Downstream development during South African cut-off low pressure systems[J],2021,249.
APA	Ndarana T.,Rammopo T.S.,Bopape M.-J.,Reason C.J.C.,&Chikoore H..(2021).Downstream development during South African cut-off low pressure systems.Atmospheric Research,249.
MLA	Ndarana T.,et al."Downstream development during South African cut-off low pressure systems".Atmospheric Research 249(2021).