Probabilities of coastal extreme water levels (EWLs) are increasing as sea levels rise. Using a time-dependent statistical model on tide gauge data along U.S. and Pacific Basin coastlines, we show that EWL probability distributions also shift on an annual basis from climate forcing and long-period tidal cycles. In some regions, combined variability (>15 cm) can be as large or larger than the amount of sea level rise (SLR) experienced over the past 30 years and projected over the next 30 years. Considering SLR and variability by 2050 at a location like La Jolla, California suggests a moderate-level (damaging) flood today with a 50-year return level (2% annual chance) would occur about 3–4 times a year during an El Nino nearing the peak of the nodal tide cycle. If interannual variability is overlooked, SLR related impacts could be more severe than anticipated based solely upon decadal-scale projections.

中文翻译：

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沿海极端水位变化和趋势的影响


随着海平面上升，沿海极端水位 (EWL) 的概率也在增加。使用美国和太平洋盆地海岸线验潮仪数据的时间相关统计模型，我们发现 EWL 概率分布也会因气候强迫和长周期潮汐周期而每年发生变化。在某些地区，综合变率（>15 厘米）可能与过去 30 年经历的海平面上升量 (SLR) 以及未来 30 年预计的海平面上升量 (SLR) 一样大或更大。考虑到 2050 年加利福尼亚州拉霍亚等地的 SLR 和变异性，预计在厄尔尼诺现象期间，今天将发生 50 年一遇的中度（破坏性）洪水（每年概率为 2%），每年大约会发生 3-4 次接近节点潮汐周期的峰值。如果忽略年际变化，与 SLR 相关的影响可能比仅基于十年尺度预测的预期更为严重。