Co-occurring wintertime flooding and extreme wind over Europe, from daily to seasonal timescales
Co-occurring wintertime flooding and extreme wind over Europe, from daily to seasonal timescales
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从每日到季节性时间尺度，欧洲同时发生冬季洪水和极端风
DOI：
10.1016/j.wace.2023.100550
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发表时间：
2023
影响因子：
8
通讯作者：
H.C. B
中科院分区：
文献类型：
--
作者：
H.C. B
现在人们怀疑暴雨和强风造成的风险因它们同时发生的方式而加剧，但人们对这一点的理解仍然不够，无法有效地规划和缓解。这项研究系统地调查了冬季（10月至3月）极端风和洪水在所有时间尺度从日常到季节之间的相关性。气象再分析和河流流量数据集用于探索历史时期，并分析了12公里分辨率的气候预测，以了解未来气候变化的可能影响（2061-2080年，RCP 8.5）。一个新的洪水严重性指数（FSI）也被开发出来，以补充现有的风暴严重性指数（SSI）。最初，英国（GB）是作为一个相对简单，但信息量大的研究领域，然后分析扩展到整个欧洲域。在GB中，阵风和降水在从每日到季节的时间尺度上具有很强的相关性（rs = 0.6-0.8），但在10天左右达到峰值。当考虑阵风和河流流量之间的相关性时，可以看到较晚的峰值（40-60天）。这段时间可能是集水区土壤饱和所需的时间。提出了一个概念性的多时相、多过程的GB冬季风洪共现模型，作为今后研究的基础。当历史分析扩展到整个欧洲时，我们发现最大相关性的时间尺度在国家之间差异很大，可能是由于不同的气象驱动因素。以影响为中心的相关性（FSI-SSI）较低（r s ≥ 0.2），但在240天的时间尺度上随着气候变化而显著增加（r s ≥ 0.4）。十年来，非常严重的事件（即都> 99百分位数）似乎受到气候变化的严重影响，到2061-2080年大约增加了三倍（p< 0.05）。此类事件的重现期在历史上为16年（如果两种危害独立，则为56年），未来缩短至5年。这些指标为保险公司和其他利益相关者提供了可操作的信息。
The risk posed by heavy rain and strong wind is now suspected to be exacerbated by the way they co-occur, yet this remains insufficiently understood to effectively plan and mitigate. This study systematically investigates the correlations between wintertime (Oct–Mar) extremes relating to wind and flooding at all timescales from daily to seasonal. Meteorological reanalysis and river flow datasets are used to explore the historical period, and climate projections at 12 km resolution are analysed to understand the possible effects of future climate change (2061–2080, RCP 8.5). A new flood severity index (FSI) is also developed to complement the existing storm severity index (SSI). Initially, Great Britain (GB) is taken as a comparatively simple yet informative study area, then analysis is extended to the full European domain. Aggregated across GB, wind gusts and precipitation correlate strongly (r s∼ 0.6–0.8) at timescales from daily to seasonal, but peak around 10 days. A later peak is seen when considering correlations between wind gusts and river flows (40–60 days). This time is likely needed for catchments’ soils to saturate. A conceptual multi-temporal, multi-process model of GB wintertime flood-wind co-occurrence is proposed as a basis for future investigation. When historical analysis is extended across Europe we find the timescale of maximum correlation varies strongly between nations, likely as a result of different meteorological drivers. Impact focused correlation (FSI–SSI) is lower (r s∼ 0.2) but increases notably with climate change at timescales of∼ 40 days (r s∼ 0.4). Tentatively, very severe episodes (ie, both> 99th percentile) appear heavily influenced by climate change, increasing roughly threefold by 2061–2080 (p< 0.05). The return period of such an event is 16 years historically (compared to 56 years if the two hazards were independent), reduces to 5 years in future. Such metrics provide actionable information for insurers and other stakeholders.