DOI: 10.1175/JCLI-D-14-00484.1
Scopus记录号: 2-s2.0-84949324404
论文题名: The annual cycle of East African precipitation
作者: Yang W. ; Seager R. ; Cane M.A. ; Lyon B.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2015
卷: 28, 期: 6 起始页码: 2385
结束页码: 2404
语种: 英语
Scopus关键词: Atmospheric temperature
; Budget control
; Climatology
; Moisture
; Precipitation (chemical)
; Rain
; Surface waters
; Tropics
; Africa
; Atmospheric circulation
; Convective stability
; Moist static energy
; Moisture/moisture budgets
; Sea surface temperature (SST)
; Seasonal cycle
; Tropical land areas
; Oceanography
; annual cycle
; arid region
; atmospheric circulation
; atmospheric convection
; convergence
; moisture flux
; precipitation (climatology)
; regional climate
; sea surface temperature
; semiarid region
; tropical meteorology
; troposphere
; East Africa
英文摘要: East African precipitation is characterized by a dry annual mean climatology compared to other deep tropical land areas and a bimodal annual cycle with the major rainy season during March-May (MAM; often called the "long rains") and the second during October-December (OND; often called the "short rains"). To explore these distinctive features, ERA-Interim data are used to analyze the associated annual cycles of atmospheric convective stability, circulation, and moisture budget. The atmosphere over East Africa is found to be convectively stable in general year-round but with an annual cycle dominated by the surface moist static energy (MSE), which is in phase with the precipitation annual cycle. Throughout the year, the atmospheric circulation is dominated by a pattern of convergence near the surface, divergence in the lower troposphere, and convergence again at upper levels. Consistently, the convergence of the vertically integrated moisture flux is mostly negative across the year, but becomes weakly positive in the two rainy seasons. It is suggested that the semiarid/arid climate in East Africa and its bimodal precipitation annual cycle can be explained by the ventilation mechanism, in which the atmospheric convective stability over East Africa is controlled by the import of low MSE air from the relatively cool Indian Ocean off the coast. During the rainy seasons, however, the off-coast sea surface temperature (SST) increases (and is warmest during the long rains season) and consequently the air imported into East Africa becomes less stable. This analysis may be used to aid in understanding overestimates of the East African short rains commonly found in coupled models. © 2015 American Meteorological Society. 资助项目: NSF, National Science Foundation
; NOAA, National Science Foundation
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/50883
Appears in Collections: 气候变化事实与影响
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作者单位: Lamont-Doherty Earth Observatory, Earth Institute, Columbia University, Palisades, NY, United States; International Research Institute for Climate and Society, Lamont-Doherty Earth Observatory, Earth Institute, Columbia University, Palisades, NY, United States
Recommended Citation:
Yang W.,Seager R.,Cane M.A.,et al. The annual cycle of East African precipitation[J]. Journal of Climate,2015-01-01,28(6)