Tropical Cyclogenesis within an Equatorial Rossby Wave Packet
Tropical Cyclogenesis within an Equatorial Rossby Wave Packet
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DOI：
10.1175/jas3902.1
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发表时间：
2007-04
影响因子：
3.1
通讯作者：
J. Molinari;K. Lombardo;David Vollaro
中科院分区：
文献类型：
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作者：
J. Molinari;K. Lombardo;David Vollaro
摘要在西北太平洋对流层低层发现了一个持续2.5个月的赤道Rossby波包。包内的波周期为22天，波长为3600公里，向西相速度为1.9 m s-1，群速度接近于零。在25 m附近的等效深度，波动特性遵循ER波频散关系。这一天气系统与13个热带气旋中至少8个的发展有关。一个合成图是围绕着起源点建立的。热带气旋形成于复合ER波低中心以东的一个强对流区域和一个单独的850百帕涡度最大值。在包的生命周期的背景流的特点是850百帕纬向风辐合和东风垂直风切变。波振幅在辐合区的伦敦西区达到峰值，表明波的积累在包的增长中起了重要作用。东风波的出现...
Abstract A packet of equatorial Rossby (ER) waves that lasted 2.5 months is identified in the lower troposphere of the northwest Pacific. Waves within the packet had a period of 22 days, a wavelength of 3600 km, a westward phase speed of 1.9 m s−1, and a near-zero group speed. The wave properties followed the ER wave dispersion relation with an equivalent depth near 25 m. The packet was associated with the development of at least 8 of the 13 tropical cyclones that formed during the period. A composite was constructed around the genesis locations. Tropical cyclones formed east of the center of the composite ER wave low in a region of strong convection and a separate 850-hPa vorticity maximum. The background flow during the life of the packet was characterized by 850-hPa zonal wind convergence and easterly vertical wind shear. Wave amplitude peaked at the west end of the convergent region, suggesting that wave accumulation played a significant role in the growth of the packet. The presence of easterly verti...