DOI: 10.1007/s00382-011-1045-x
Scopus记录号: 2-s2.0-84857444496
论文题名: The role of the Indian monsoon onset in the West African monsoon onset: Observations and AGCM nudged simulations
作者: Flaounas E. ; Janicot S. ; Bastin S. ; Roca R. ; Mohino E.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2012
卷: 38, 期: 2017-05-06 起始页码: 965
结束页码: 983
语种: 英语
英文关键词: Atmospheric general circulation models
; Dry-air intrusions
; Indian monsoon onset
; Madden-Julian
; Nudging
; Oscillation
; West African monsoon onset
英文摘要: In spring the inland penetration of the West African Monsoon (WAM) is weak and the associated rainband is located over the Guinean coast. Then within a few days deep convection weakens considerably and the rainband reappears about 20 days after over the Sahel, where it remains until late September signalling the summer rainy season. Over the period 1989-2008 a teleconnection induced by the Indian monsoon onset is shown to have a significant impact on the WAM onset, by performing composite analyses on both observational data sets and atmospheric general circulation model simulations ensembles where the model is nudged to observations over the Indian monsoon sector. The initiation of convective activity over the Indian subcontinent north of 15°N at the time of the Indian monsoon onset results in a westward propagating Rossby wave establishing over North Africa 7-15 days after. A back-trajectory analysis shows that during this period, dry air originating from the westerly subtropical jet entrance is driven to subside and move southward over West Africa inhibiting convection there. At the same time the low-level pressure field over West Africa reinforces the moisture transport inland. After the passage of the wave, the dry air intrusions weaken drastically. Hence 20 days after the Indian monsoon onset, convection is released over the Sahel where thermodynamic conditions are more favourable. This scenario is very similar in the observations and in the nudged simulations, meaning that the Indian monsoon onset is instrumental in the WAM onset and its predictability at intraseasonal scale. © 2011 Springer-Verlag. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/55360
Appears in Collections: 过去全球变化的重建
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作者单位: LATMOS/IPSL, Université Pierre et Marie Curie, Boite 102, 4 Place Jussieu, 75252 Paris cedex 05, France; LOCEAN/IPSL, IRD, Université Pierre et Marie Curie, Paris, France; LATMOS/IPSL, CNRS, Université Pierre et Marie Curie, Paris, France; LMD/IPSL, CNRS, Université Pierre et Marie Curie, Paris, France; LOCEAN/IPSL, CNRS, Université Pierre et Marie Curie, Paris, France; Universidad de Sevilla, Sevilla, Spain
Recommended Citation:
Flaounas E.,Janicot S.,Bastin S.,et al. The role of the Indian monsoon onset in the West African monsoon onset: Observations and AGCM nudged simulations[J]. Climate Dynamics,2012-01-01,38(2017-05-06)