Tornadoes are a co-occurring extreme that can be produced by landfalling tropical cyclones (TCs). These tornadoes can exacerbate the loss of life and property damage caused by the TC from which they were spawned. It is uncertain how the severe weather environments of landfalling TCs may change in a future climate and how this could impact tornado activity from TCs. In this study, we investigated four TCs that made landfall in the U.S. and produced large tornado outbreaks. We performed four-member ensembles of convective-allowing (4-km resolution) regional climate model simulations representing each TC in the historical climate and a mid-twenty-first century future climate. To identify potentially tornadic storms, or TC-tornado (TCT) surrogates, we used thresholds for three-hourly maximum updraft helicity and radar reflectivity, as tornadoes are not resolved in the model. We found that the ensemble-mean number of TCT-surrogates increased substantially (56–299%) in the future, supported by increases in most-unstable convective available potential energy, surface-to-700-hPa bulk wind shear, and 0–1-km storm-relative helicity in the tornado-producing region of the TCs. On the other hand, future changes in most-unstable convective inhibition had minimal influence on future TCT-surrogates. This provides robust evidence that tornado activity from TCs may increase in the future. Furthermore, TCT-surrogate frequency between 00Z and 09Z increased for three of the four cases, suggesting enhanced tornado activity at night, when people are asleep and more likely to miss warnings. All of these factors indicate that TC-tornadoes may become more frequent and a greater hazard in the future, compounding impacts from future increases in TC winds and precipitation.

中文翻译：

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本世纪中叶气候变化对产生龙卷风的热带气旋的影响


龙卷风是一种同时发生的极端现象，由登陆的热带气旋 (TC) 产生。这些龙卷风会加剧其产生地 TC 造成的生命损失和财产损失。目前尚不清楚登陆的热带气旋的恶劣天气环境在未来的气候中可能会如何变化，以及这将如何影响热带气旋的龙卷风活动。在这项研究中，我们调查了四个登陆美国并引发大规模龙卷风爆发的热带气旋。我们进行了四人组的允许对流（4公里分辨率）区域气候模型模拟，代表了每个热带气旋的历史气候和二十一世纪中叶的未来气候。为了识别潜在的龙卷风或 TC 龙卷风 (TCT) 替代品，我们使用了三小时最大上升气流螺旋度和雷达反射率的阈值，因为龙卷风在模型中未得到解决。我们发现，在最不稳定的对流可用势能、地表至 700 hPa 整体风切变和 0- TC 龙卷风产生区的 1 公里风暴相对螺旋度。另一方面，最不稳定的对流抑制的未来变化对未来 TCT 替代物的影响很小。这提供了强有力的证据，表明来自热带气旋的龙卷风活动在未来可能会增加。此外，四个案例中的三个在 00Z 和 09Z 之间的 TCT 替代频率有所增加，这表明夜间龙卷风活动增强，此时人们正在睡觉，更有可能错过警告。所有这些因素都表明，未来热带气旋龙卷风可能会变得更加频繁，危害也更大，从而加剧未来热带风和降水增加的影响。