DOI: 10.1175/JCLI-D-14-00146.1
Scopus记录号: 2-s2.0-84906872166
论文题名: The intraseasonal variability of African easterly wave energetics
作者: Alaka Jr. G.J. ; Maloney E.D.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2014
卷: 27, 期: 17 起始页码: 6559
结束页码: 6580
语种: 英语
Scopus关键词: Budget control
; Energy conversion
; Kinetics
; African easterly jet
; African easterly waves
; Diabatic heating
; Intra-seasonal
; Intraseasonal time scale
; Intraseasonal variability
; Meridional temperature gradient
; North Africa
; Climate change
英文摘要: African easterly waves (AEWs) and associated perturbation kinetic energy (PKE) exhibit significant intraseasonal variability in tropical North Africa during boreal summer. Consistent with East Africa (e.g., east of Lake Chad) being an initiation region forAEWs, previous studies have shown that increased EastAfrican PKE precedes and leads to increasedWestAfricanAEWactivity on intraseasonal time scales. In this study, reanalysis budgets of PKE and perturbation available potential energy (PAPE) are used to understand this behavior. The variability of PKE and PAPE sources is analyzed as a function ofMadden-Julian oscillation (MJO) phase and a local 30-90-day West African PKE index to diagnose when and where eddy energy conversions terms are important to periods of increased or decreased intraseasonal AEW activity. In East Africa, an increased meridional temperature gradient locally enhances baroclinic energy conversion anomalies to initiate periods of increased intraseasonal AEW activity. Downstream barotropic and baroclinic energy conversions associated with strongAEWs are important for themaintenance of intraseasonalAEWactivity inWestAfrica. Barotropic energy conversions dominate south of the African easterly jet (AEJ), while baroclinic energy conversions are most important north of the AEJ. In both East and West Africa, diabatic heating does not appear to aid intraseasonal PKEcreation. Instead, negative PAPEtendency anomalies due to the diabatic heating-temperature covariance act as a negative feedback to increased baroclinic energy conversion downstream in the AEJ. © 2014 American Meteorological Society. 资助项目: NOAA, National Oceanic and Atmospheric Administration
; NOAA, National Oceanic and Atmospheric Administration
; NOAA, National Oceanic and Atmospheric Administration
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/51447
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Atmospheric Science, Colorado State University, Fort Collins, CO, United States
Recommended Citation:
Alaka Jr. G.J.,Maloney E.D.. The intraseasonal variability of African easterly wave energetics[J]. Journal of Climate,2014-01-01,27(17)