A Numerical Study of the 6 May 2012 Tsukuba City Supercell Tornado. Part I: Vorticity Sources of Low-Level and Midlevel Mesocyclones
A Numerical Study of the 6 May 2012 Tsukuba City Supercell Tornado. Part I: Vorticity Sources of Low-Level and Midlevel Mesocyclones
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DOI：
10.1175/mwr-d-15-0123.1
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发表时间：
2016-02
影响因子：
3.2
通讯作者：
Wataru Mashiko
中科院分区：
文献类型：
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作者：
Wataru Mashiko
2012年5月6日，日本有记录以来最具破坏性的龙卷风之一F3超级单体龙卷风袭击了日本东部的筑波市，造成了严重的破坏。为了弄清龙卷风和龙卷风的产生机制，采用三重嵌套网格对实际环境条件下的龙卷风和龙卷风进行了高分辨率数值模拟。在这项研究中，通过对涡线和中气旋环流演变的分析，研究了龙卷风发生前中气旋发生的涡量来源。通过4公里高的中层中气旋的涡线来源于环境流向涡度，而低层中气旋和低层中高压在后侧下沉气流上有几条拱形涡线相连，与水汽的钩状分布有关。
AbstractOn 6 May 2012, an F3 supercell tornado, one of the most destructive tornadoes ever recorded in Japan, hit Tsukuba City in eastern Japan and caused severe damage. To clarify the generation mechanisms of the tornadic storm and tornado, high-resolution numerical simulations were conducted under realistic environmental conditions using triply nested grids. The innermost simulation with a 50-m mesh successfully reproduced the Tsukuba City tornadic supercell storm.In this study (the first of a two-part study), the vorticity sources responsible for mesocyclogenesis prior to tornadogenesis were investigated by analyzing vortex lines and the evolution of circulation of the mesocyclones. Vortex lines that passed through the midlevel mesocyclone (4-km height) originated from the environmental streamwise vorticity, whereas the low-level mesocyclone and low-level mesoanticyclone were connected by several arching vortex lines over the rear-flank downdraft associated with the hook-shaped distribution of hydromet...