The role of tropical waves in tropical cyclogenesis
The role of tropical waves in tropical cyclogenesis
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DOI：
10.1175/mwr3204.1
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发表时间：
2006-09-01
影响因子：
3.2
通讯作者：
Roundy, Paul E.
中科院分区：
文献类型：
--
作者：
Frank, William M.;Roundy, Paul E.
本文分析了地球上所有主要热带气旋盆地的热带波活动与热带气旋形成的关系。对29年的外发长波辐射数据和全球再分析风进行了过滤和分析，以确定每个盆地的波活动与相应的气旋形成之间的统计关系。与风暴发生位置相关的综合分析显示了波浪的结构及其与风暴发生的优先相位关系。本研究考察了五种波类型，包括混合罗斯比重力波、热带低气压型或东风波、赤道罗斯比波、开尔文波和马登-朱利安振荡。后者不是经典的热带波类型之一，而是一种已知对热带气旋形成有强烈影响的波状现象。热带气旋的形成与除开尔文带外所有滤波带的活动增强密切相关。各盆地各复合波的构造及其与旋流形成的相位关系相似，表明其强迫机制一致。这些波通过增加强迫上升的垂直运动、增加低层涡度以及调节垂直切变来增强局地环流。与成因有关的对流异常在成因前1个月的分析中就可探测到。这为发展基于统计的起源预测提供了可能性。
This paper analyzes relationships between tropical wave activity and tropical cyclogenesis in all of the earth's major tropical cyclone basins. Twenty-nine years of outgoing longwave radiation data and global reanalysis winds are filtered and analyzed to determine statistical relationships between wave activity in each basin and the corresponding cyclogenesis. Composite analyses relative to the storm genesis locations show the structures of the waves and their preferred phase relationships with genesis. Five wave types are examined in this study, including mixed Rossby-gravity waves, tropical-depression-type or easterly waves, equatorial Rossby waves, Kelvin waves, and the Madden-Julian oscillation. The latter is not one of the classical tropical wave types, but is a wavelike phenomenon known to have a strong impact on tropical cyclogenesis. Tropical cyclone formation is strongly related to enhanced activity in all of the wave filter bands except for the Kelvin band. In each basin the structure of each composite wave and the phase relationship between the wave and cyclogenesis are similar, suggesting consistent forcing mechanisms. The waves appear to enhance the local circulations by increasing the forced upward vertical motion, increasing the low-level vorticity at the genesis location, and by modulating the vertical shear. Convective anomalies of waves associated with genesis are detectable in the analyses as long as 1 month prior to genesis. This opens up the possibility of developing statistically based genesis forecasts.