Recently, the intensity and frequency of heat waves (HWs) have been increased worldwide. Particularly in 2022, Europe was severely affected by unprecedented HWs, which caused approximately 61,672 deaths and 11,324 deaths in Europe and Spain, respectively. In this study, we investigate the mechanisms of the HWs in southwestern Europe (SWEU) to identify the differences between typical HWs and the extreme HWs that occurred in 2022. Our results showed that the SWEU events in 2022 were strongly related to robust heat domes that developed in the lower troposphere due to high-pressure anomalies especially during two periods (9–18 June and 8–19 July). Analyses of the energy budget and thermodynamic equation revealed the processes underlying the amplification of the heat domes over SWEU during both periods. We also discovered that abnormal atmospheric blocking in the upper troposphere was closely associated with the amplification of the Gulf Stream SST, which caused an atmospheric circulation pattern favorable for the 2022 SWEU-HWs. This was further confirmed by modeling experiments. Therefore, our results emphasize that a Gulf Stream SST amplification can trigger an atmospheric circulation pattern favorable for extreme HWs in SWEU, enhancing our understanding of the mechanism behind extreme HWs. Finally, our findings will help improving the forecasting of SWEU-HWs on a sub-seasonal time scale, as well as future projections in global climate models.

中文翻译：

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2022 年欧洲西南部创纪录的热浪及其潜在机制


最近，全球热浪 （HW） 的强度和频率有所增加。特别是在 2022 年，欧洲受到前所未有的 HW 的严重影响，欧洲和西班牙分别造成约 61,672 人和 11,324 人死亡。在这项研究中，我们调查了西南欧 HWs 的机制 （SWEU），以确定典型 HWs 和 2022 年发生的极端 HWs 之间的差异。我们的结果表明，2022 年的 SWEU 事件与由于高压异常在对流层低层形成的强大热穹顶密切相关，尤其是在两个时期（6 月 9 日至 18 日和 7 月 8 日至 19 日）。对能量收支和热力学方程的分析揭示了这两个时期 SWEU 上热穹顶放大的过程。我们还发现，对流层上部的异常大气阻塞与墨西哥湾流 SST 的放大密切相关，这导致了有利于 2022 SWEU-HW 的大气环流模式。建模实验进一步证实了这一点。因此，我们的结果强调墨西哥湾流 SST 放大可以触发有利于 SWEU 中极端 HW 的大气环流模式，从而增强我们对极端 HW 背后机制的理解。最后，我们的研究结果将有助于改进亚季节时间尺度上对 SWEU-HW 的预测，以及全球气候模型的未来预测。