DOI: 10.1007/s00382-012-1579-6
Scopus记录号: 2-s2.0-84886724050
论文题名: Cut-off Lows in the South Africa region and their contribution to precipitation
作者: Favre A. ; Hewitson B. ; Lennard C. ; Cerezo-Mota R. ; Tadross M.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2013
卷: 41, 期: 2017-09-10 起始页码: 2331
结束页码: 2351
语种: 英语
英文关键词: Antarctic oscillation
; Cut-off Low
; El Niño Southern Oscillation
; Pacific South American pattern
; Precipitation
; Semiannual oscillation
; South Africa
英文摘要: The contribution of Cut-off Lows (CoLs) to precipitation and extreme rainfall frequency in South Africa has been quantified from 402 station records over the period 1979-2006. Firstly, 500 hPa CoL trajectories over Southern Africa and surrounding oceans were determined and their features thoroughly analyzed. In a second step, using daily precipitable water, outgoing long wave radiation data and station rainfall records, an area was defined where the occurrence of CoLs is associated with rainfall over South Africa. CoLs transiting in the 2.5°E-32.5°E/20°S-45°S are more likely to produce precipitation over the country. When 500 hPa CoLs are centered just off the west coast of the country (around 15°E/32.5°S) their impact is substantial in term of daily rainfall intensity and spatial coverage. CoL rainy days have been studied and it is shown that they significantly contribute to precipitation in South Africa, more strongly along the south and east coasts as well as inland, over the transition zone between the summer and winter rainfall domains where they contribute between 25 to more than 35 % of annual accumulation. At the country scale, CoL rainfall is more intense and widespread in spring than during other seasons. Over the analyzed period, a significant trend in annual CoLs' frequency shows an increase of about 25 %. This increase is mainly realized in spring and in a lesser extent in summer. This trend is accompanied by a significant increase in the frequency of CoL rainy days specifically along the south coast and over the East of the country during the spring-summer period. In parallel, it is shown that from late spring until summer CoLs' frequency varies significantly accordingly with large scale circulation modes of the Southern Hemisphere such as the Pacific South American pattern (PSA). This positive trend in CoLs' frequency may be related with the positive trend in the PSA during the spring-summer period over the three last decades. © 2012 Springer-Verlag Berlin Heidelberg. 资助项目: National Research Foundation
Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/54744
Appears in Collections: 过去全球变化的重建
There are no files associated with this item.
作者单位: Climate System Analysis Group, ENGEO Department, University of Cape Town, Cape Town, South Africa; Centre de Recherches de Climatologie, UMR 6282 Biogéosciences CNRS, Universitée de Bourgogne, 6 boulevard Gabriel, 2100 Dijon, France; Institute of Environment and Sustainability, UCLA, Los Angeles, CA, United States
Recommended Citation:
Favre A.,Hewitson B.,Lennard C.,et al. Cut-off Lows in the South Africa region and their contribution to precipitation[J]. Climate Dynamics,2013-01-01,41(2017-09-10)