Astronomical variations in tidal magnitude can strongly modulate the severity of coastal flooding on daily, monthly, and interannual timescales. Here we present a new quasi‐nonstationary skew surge joint probability method (qn‐SSJPM) that estimates interannual fluctuations in flood hazard caused by the 18.6‐ and quasi 4.4‐year modulations of tides. We demonstrate that qn‐SSJPM‐derived storm tide frequency estimates are more precise and stable compared with the standard practice of fitting an extreme value distribution to measured storm tides, which is often biased by the largest few events within the observational period. Applying the qn‐SSJPM in the Gulf of Maine, we find significant tidal forcing of winter storm season flood hazard by the 18.6‐year nodal cycle, whereas 4.4‐year modulations and a secular trend in tides are small compared to interannual variation and long‐term trends in sea‐level. The nodal cycle forces decadal oscillations in the 1% annual chance storm tide at an average rate of ±13.5 mm/year in Eastport, ME; ±4.0 mm/year in Portland, ME; and ±5.9 mm/year in Boston, MA. Currently (in 2020), nodal forcing is counteracting the sea‐level rise‐induced increase in flood hazard; however, in 2025, the nodal cycle will reach a minimum and then begin to accelerate flood hazard increase as it moves toward its maximum phase over the subsequent decade. Along the world's meso‐to‐macrotidal coastlines, it is therefore critical to consider both sea‐level rise and tidal nonstationarity in planning for the transition to chronic flooding that will be driven by sea‐level rise in many regions over the next century.

中文翻译：

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缅因湾极端海平面频率的潮汐驱动年际变化

潮汐量的天文变化可以在每日，每月和每年的时间尺度上强烈调节沿海洪水的严重性。在这里，我们提出了一种新的准非平稳偏斜喘振联合概率方法（qn-SSJPM），该方法估计了由潮汐的18.6年和准4.4年调制引起的洪水灾害的年际波动。我们证明，与将极值分布拟合到测得的风暴潮的标准做法相比，qn-SSJPM得出的风暴潮频率估计更加精确和稳定，而观测值通常会受到最大事件的影响。在缅因州海湾应用qn-SSJPM，我们发现在18.6年的节点周期中，冬季风暴季节洪水灾害的潮汐强迫显着，而4。与年际变化和海平面的长期趋势相比，四年调制和潮汐的长期趋势较小。在缅因州的伊斯特波特，节点周期以1％的年平均暴风潮速度强迫年代际振荡，平均速度为±13.5毫米/年。缅因州波特兰市，每年±4.0毫米；和在马萨诸塞州的波士顿，每年±5.9毫米。目前（2020年），节点强迫正在抵消海平面上升引起的洪水灾害的增加。但是，到2025年，节点周期将达到最小，然后在随后的十年中朝最大阶段发展时，开始加速洪灾危险的增加。因此，在世界上从中到大卵圆的海岸线上，在计划下一个世纪中许多地区的海平面上升将导致向慢性洪水过渡的计划中，必须考虑海平面上升和潮汐非平稳性。