The Madden–Julian Oscillation’s Influence on African Easterly Waves and Downstream Tropical Cyclogenesis
The Madden–Julian Oscillation’s Influence on African Easterly Waves and Downstream Tropical Cyclogenesis
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马登-朱利安涛动对非洲东波和下游热带气旋的影响
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
P. Roundy
中科院分区：
文献类型：
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作者：
Michael J. Ventrice;C. Thorncroft;P. Roundy
摘要探讨了北半球夏季夏季马登-朱利安涛动（MJO）对热带非洲和大西洋的影响。采用实时多变量MJO （RMM）指标对MJO进行评价。这些指标将MJO的有效对流信号划分为8个相位。在RMM第8、1和2阶段，与MJO相关的对流在热带非洲上空增强。在随后的RMM阶段（第3-7阶段），热带非洲上空的对流受到抑制。非洲对流信号与向西传播的赤道罗斯比波有关。MJO调节非洲东风波（AEW）活动。AEW活动在RMM第1-3期局部增强，在RMM第6-8期局部抑制。在热带非洲上空对流增强期间，预警机活动增强，这与预警机更强或更频繁地触发以及与潜热释放相关的更多增长相一致。的低空西风阶段，预警活动增强。
AbstractThe influence of the Madden–Julian oscillation (MJO) over tropical Africa and Atlantic is explored during the Northern Hemisphere summer months. The MJO is assessed by using real-time multivariate MJO (RMM) indices. These indices divide the active convective signal of the MJO into 8 phases. Convection associated with the MJO is enhanced over tropical Africa during RMM phases 8, 1, and 2. Convection becomes suppressed over tropical Africa during the subsequent RMM phases (phases 3–7). African convective signals are associated with westward-propagating equatorial Rossby waves.The MJO modulates African easterly wave (AEW) activity. AEW activity is locally enhanced during RMM phases 1–3 and suppressed during RMM phases 6–8. Enhanced AEW activity occurs during periods of enhanced convection over tropical Africa, consistent with stronger or more frequent triggering of AEWs as well as more growth associated with latent heat release. Enhanced AEW activity occurs during the low-level westerly wind phase of...