Heavy Precipitation over Italy from the Mediterranean Storm “Vaia” in October 2018: Assessing the Role of an Atmospheric River
Heavy Precipitation over Italy from the Mediterranean Storm “Vaia” in October 2018: Assessing the Role of an Atmospheric River
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DOI：
10.1175/mwr-d-20-0021.1
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发表时间：
2020-09
影响因子：
3.2
通讯作者：
S. Davolio;S. D. Fera;S. Laviola;M. Miglietta;V. Levizzani
中科院分区：
文献类型：
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作者：
S. Davolio;S. D. Fera;S. Laviola;M. Miglietta;V. Levizzani
地中海风暴“瓦伊亚”是在一个典型的秋季天气环流中发展起来的，通常与西地中海盆地的暴雨有关。2018年10月27日至30日期间，强烈降水导致意大利多地发生洪灾，风暴还伴随着爆炸性气旋生成、风暴潮和极端强烈的阵风，造成人员伤亡和广泛破坏，尤其是对阿尔卑斯山森林的破坏。本研究探讨了不同的水分来源的极端降水的数值模式模拟使用博洛尼亚有限区域模式（BOLAM）。特别是，注意力集中在大量的水蒸气从大西洋热带地区输送到地中海盆地，并有组织的沿着一条狭窄的走廊横跨非洲大陆。首先，一个新开发的检测算法被应用到识别这种运输作为一个大气河流（AR）。然后，实施的大气水预算诊断，敏感性实验的支持下，使我们能够评估的AR在降水系统供水方面的作用。虽然从偏远地区输送的水分是已知的一个重要组成部分，在地中海的强降水的发病，AR的作用，已经确定在对应于这些事件中的一些，还没有深入研究和量化，但在这个特定的领域。结果表明，AR是决定意大利强降水事件的大小的关键，而从海上蒸发起了次要作用，特别是在阿尔卑斯山的降水。
The Mediterranean storm “Vaia” developed within a typical autumn synoptic circulation, generally associated with heavy rain conditions over the western Mediterranean Sea basin. Intense precipitation was responsible for floods over Italy between 27 and 30 October 2018, and the storm was accompanied by explosive cyclogenesis, storm surge, and extremely intense wind gusts that caused casualties and extensive damage, especially to the Alpine forests. This study investigates the contribution of different moisture sources to the extreme precipitation by means of numerical model simulations using the Bologna Limited Area Model (BOLAM). In particular, the attention is focused on the significant amount of water vapor transported into the Mediterranean basin from the Atlantic Ocean tropical area and organized along a narrow corridor across the African continent. First, a newly developed detection algorithm is applied to identify this transport as an atmospheric river (AR). Then, the implementation of an atmospheric water budget diagnostic, supported by sensitivity experiments, allows us to assess the role of the AR in terms of water supply to the precipitation systems. Although the transport of moisture from remote regions is known to be an important ingredient for the onset of heavy precipitation in the Mediterranean, the role of ARs, already identified in correspondence with some of these events, has not been deeply investigated and quantified yet in this specific area. The results demonstrate that the AR was critical for determining the magnitude of this heavy precipitation episode over Italy, whereas evaporation from the sea played a secondary role, especially for precipitation over the Alps.