Is There a “Tipping Point” between Simulated Nontornadic and Tornadic Supercells in VORTEX2 Environments?
Is There a “Tipping Point” between Simulated Nontornadic and Tornadic Supercells in VORTEX2 Environments?
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VORTEX2 环境中模拟的非龙卷风和龙卷风超级单体之间是否存在“临界点”？
DOI：
10.1175/mwr-d-18-0050.1
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发表时间：
2018
影响因子：
3.2
通讯作者：
Parker, Matthew D.
中科院分区：
文献类型：
--
作者：
Coffer, Brice E.;Parker, Matthew D.
以前的工作表明，低对流层的风廓线可能部分决定了超级单体是否会变成龙卷风。如果VORTEX2复合环境中的龙卷风发生对低对流层风比对上对流层风或热力廓线更敏感，那么系统地改变低对流层风廓线可能会揭示非龙卷风和龙卷风超级单体之间的“转折点”。作为一项测试，模拟的超级单体是在非龙卷风和龙卷风VORTEX2超级单体复合体的低层风廓线之间逐渐内插的环境中启动的，同时也交换了上层对流层风和热力学廓线。当低层风廓线包含来自龙卷风VORTEX2复合环境的至少40%的结构时，模拟的超级单体变得龙卷风。非龙卷风风暴和龙卷风风暴在上升气流附近都有相似的外流温度和地表垂直涡度。最明显的是，一个强大的低层中气旋和上升气流立即覆盖了每个龙卷风超级单体中不断增强的近地表环流。非龙卷风超级单体的低层上升气流是杂乱无章的，在地面垂直涡度所在的整个地区都有下降的小块。无论VORTEX2合成的对流层风廓线或热力廓线如何，低对流层风廓线都驱动着这些不同的低层中气旋和上升气流构型。因此，这项研究支持了超级单体龙卷风发生的可能性与对流层低层风廓线之间潜在的有用的、强有力的联系，当最低数百米的水平涡度方向是流向(横向)时，龙卷风发生的可能性更大(更小)。
Previous work has suggested that the lower-tropospheric wind profile may partly determine whether supercells become tornadic. If tornadogenesis within the VORTEX2 composite environments is more sensitive to the lower-tropospheric winds than to either the upper-tropospheric winds or the thermodynamic profile, then systematically varying the lower-tropospheric wind profile might reveal a “tipping point” between nontornadic and tornadic supercells. As a test, simulated supercells are initiated in environments that have been gradually interpolated between the low-level wind profiles of the nontornadic and tornadic VORTEX2 supercell composites while also interchanging the upper-tropospheric winds and thermodynamic profile. Simulated supercells become tornadic when the low-level wind profile incorporates at least 40% of the structure from the tornadic VORTEX2 composite environment. Both the nontornadic and tornadic storms have similar outflow temperatures and availability of surface vertical vorticity near their updrafts. Most distinctly, a robust low-level mesocyclone and updraft immediately overlie the intensifying near-surface circulation in each of the tornadic supercells. The nontornadic supercells have low-level updrafts that are disorganized, with pockets of descent throughout the region where surface vertical vorticity resides. The lower-tropospheric wind profile drives these distinct configurations of the low-level mesocyclone and updraft, regardless of the VORTEX2 composite upper-tropospheric wind profile or thermodynamic profile. This study therefore supports a potentially useful, robust link between the probability of supercell tornadogenesis and the lower-tropospheric wind profile, with tornadogenesis more (less) likely when the orientation of horizontal vorticity in the lowest few hundred meters is streamwise (crosswise).
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影响因子：
3.1
作者：
Johannes M. L. Dahl;M. Parker;Louis J. Wicker
通讯作者：
Johannes M. L. Dahl;M. Parker;Louis J. Wicker
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DOI：
--
发表时间：
2015
期刊：
影响因子：
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作者：
Johannes M. L. Dahl
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Johannes M. L. Dahl
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DOI：
--
发表时间：
2012
期刊：
影响因子：
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作者：
J. Naylor;M. Gilmore
通讯作者：
M. Gilmore
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影响因子：
3.2
作者：
A. Wade;M. Coniglio;C. Ziegler
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DOI：
--
发表时间：
2014
期刊：
影响因子：
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作者：
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