重建法国大西洋沿岸历史极端偏移涌浪,提升沿海风险评估精度。
Multi-site modelling and reconstruction of past extreme skew surges along the French Atlantic coast
- 基于多站点极值依赖结构建模,用阈值法识别极端事件。
- 融合150年以上长序列数据,重建短时序站点的历史涌浪。
- 提出新回归框架,仅凭输入变量方向即可精准预测极值。
准确建模极端偏移涌浪对沿海风险管理至关重要。本研究聚焦法国大西洋沿岸极端偏移涌浪建模,重点分析站点间的极值依赖关系。采用峰度超阈值框架,定义当至少一个站点出现大值即为多变量极值事件。提出一种新型阈值确定方法。采用两种互补策略:一是利用多变量广义帕累托分布建模极值,构建生成模型,基于邻近站点观测值预测某站点极值;二是评估一种新型极值回归框架,仅需输入变量的“方向”(即变量除以其范数)即可实现精确点预测。最终目标是重建观测记录较短站点的历史偏移涌浪序列。通过整合布雷斯特和圣纳扎尔等长记录站点超过150年的数据,实现该目标。
原文摘要 · Abstract (English)
Appropriate modelling of extreme skew surges is crucial, particularly for coastal risk management. Our study focuses on modelling extreme skew surges along the French Atlantic coast, with a particular emphasis on investigating the extremal dependence structure between stations. We employ the peak-over-threshold framework, where a multivariate extreme event is defined whenever at least one location records a large value, though not necessarily all stations simultaneously. A novel method for determining an appropriate level (threshold) above which observations can be classified as extreme is proposed. Two complementary approaches are explored. First, the multivariate generalized Pareto distribution is employed to model extremes, leveraging its properties to derive a generative model that predicts extreme skew surges at one station based on observed extremes at nearby stations. Second, a novel extreme regression framework is assessed for point predictions. This specific regression framework enables accurate point predictions using only the 'angle' of input variables, i.e., input variables divided by their norms. The ultimate objective is to reconstruct historical skew surge time series at stations with limited data. This is achieved by integrating extreme skew surge data from stations with longer records, such as Brest and Saint-Nazaire, which provide over 150 years of observations.
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