DOI: 10.1002/2016JD025736
论文题名: Circulation controls on southern African precipitation in coupled models: The role of the Angola Low
作者: Munday C. ; Washington R.
刊名: Journal of Geophysical Research: Atmospheres
ISSN: 2169897X
出版年: 2017
卷: 122, 期: 2 起始页码: 861
结束页码: 877
语种: 英语
英文关键词: Angola Low
; CMIP5
; Kalahari Heat Low
; moisture circulation
; southern African rainfall
Scopus关键词: CMIP
; convergence
; general circulation model
; heating
; moisture flux
; precipitation (climatology)
; rainfall
; seasonal variation
; Angola
; Indian Ocean
; Mozambique Channel
英文摘要: In southern Africa, models from the latest Coupled Model Intercomparison Project produce a wide variety of rainfall climatologies. Differences between models in rainfall amount reach 70% in the rainy season (December–February; DJF), and the median model overestimates rainfall by between 15 and 40% throughout the annual cycle. This paper investigates the role of an understudied regional circulation feature, the Angola Low, in differentiating between model estimates of precipitation. In austral spring, the Angola Low is a heat low, driven by strong surface heating whereas in DJF it is more similar to a tropical low and is associated with moist instability. In the austral summer, we find that the simulated strength of the Angola Low is associated with between 40 and 60% of the intermodel variability in model mean rainfall across the subcontinent. The relationship is particularly strong along a northwest, southeast axis aligned from Angola down to the Mozambican Channel. Along this axis, models with stronger Angola Lows simulate enhanced, by up to 50 g kg−1 ms−1, northeasterly and northwesterly moisture transport. The enhanced southward moisture flux in models with relatively deep Angola Lows increases the rate of moisture convergence in central areas of the subcontinent and reduces moisture divergence across the Mozambican coast. The results highlight the need to better understand the links between the Angola Low and southern African rainfall and suggest that improving the simulation of the Angola Low can help to constrain model estimates of southern African rainfall. ©2017. The Authors. 资助项目: ACR00400
; NE/L002612/1
; NE/M017206
; NE/M020207/1
Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/62724
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: School of Geography and the Environment, University of Oxford, Oxford, United Kingdom
Recommended Citation:
Munday C.,Washington R.. Circulation controls on southern African precipitation in coupled models: The role of the Angola Low[J]. Journal of Geophysical Research: Atmospheres,2017-01-01,122(2)