DOI: 10.1007/s00382-017-3801-z
Scopus记录号: 2-s2.0-85025464355
论文题名: Austral summer Southern Africa precipitation extremes forced by the El Niño-Southern oscillation and the subtropical Indian Ocean dipole
作者: Hoell A. ; Cheng L.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2018
卷: 50, 期: 2018-09-10 起始页码: 3219
结束页码: 3236
语种: 英语
Scopus关键词: El Nino-Southern Oscillation
; Indian Ocean Dipole
; precipitation (climatology)
; precipitation intensity
; summer
; troposphere
; Southern Africa
英文摘要: Southern Africa, defined here as the African continent south of 15°S latitude, is prone to seasonal precipitation extremes during December–March that have profound effects on large populations of people. The intensity of summertime precipitation extremes can be remarkable, with wet seasons experiencing up to a doubling of the seasonal average precipitation. Recognizing the importance of understanding the causes of Southern Africa precipitation extremes for the purpose of improved early warning, an 80-member ensemble of atmospheric model simulations forced by observed time-varying boundary conditions during 1979–2016 is used to examine the mechanisms by which December–March precipitation extremes are delivered to Southern Africa and whether the El Niño-Southern Oscillation (ENSO) and the Subtropical Indian Ocean Dipole (SIOD) modify the probabilities of extreme seasonal precipitation occurrences. The model simulations reveal that the synchronous ENSO and SIOD phasing conditions the probability of December–March extreme precipitation occurrences. The probability of extreme wet seasons is greatly increased by La Niña, especially so when combined with a positive SIOD, and greatly decreased by El Niño regardless of SIOD phasing. By contrast, the probability of extreme dry seasons is increased by El Niño and is decreased by La Niña. The mechanisms by which extreme precipitation are delivered are the same regardless of ENSO and SIOD phase. Extreme wet seasons are a result of an anomalous lower tropospheric cyclone over Southern Africa that increases convergence and moisture fluxes into the region while extreme dry seasons are a result of an anomalous lower tropospheric anticyclone that decreases convergence and moisture fluxes into the region. © 2017, Springer-Verlag Berlin Heidelberg (outside the USA). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109308
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: NOAA/Earth System Research Laboratory Physical Sciences Division, 325 Broadway, Boulder, CO 80305, United States; Cooperative Institute for Research in the Environmental Sciences, University of Colorado Boulder, Boulder, CO, United States
Recommended Citation:
Hoell A.,Cheng L.. Austral summer Southern Africa precipitation extremes forced by the El Niño-Southern oscillation and the subtropical Indian Ocean dipole[J]. Climate Dynamics,2018-01-01,50(2018-09-10)