X‐band radar observations from the 2017 Inner Shelf Dynamics Experiment (ISDE) in central California show multiple persistent and pulsatory rip currents on a relatively straight coastline with alongshore‐varying bathymetry. Although past studies have assessed the characteristics of transient rip currents on alongshore uniform beaches, the relative balance of transient versus steady rip current behavior on nonuniform beaches in realistic wave conditions remains poorly understood. Here, a phase‐resolving Boussinesq‐type wave model (funwaveC) is used to assess the role of alongshore‐varying bathymetry and incident conditions in controlling mean and transient surf zone vorticity and velocity fields and their effect on surf zone exchange. The model simulates wave conditions chosen from the ISDE observations and utilizes both an alongshore‐varying bathymetry estimated from the ISDE radar observations and a uniform bathymetry. Results show that the variable bathymetry significantly increases the alongshore‐ and time‐averaged kinetic energy but that this increase is primarily due to the increase in the standing component resulting from mean circulation patterns, with only small changes in the transient component. A variable bathymetry also increases the spectral energy of surf zone vorticity and time‐averaged vorticity forcing at large spatial scales (>100 m). Wave directional spreading has a large impact on the alongshore‐ and time‐averaged enstrophy and on the spectral energy of surf zone vorticity and vorticity forcing at smaller spatial scales (<100 m). In the presence of a directionally spread wavefield, an alongshore‐varying bathymetry slightly increases the total exchange velocity but has little effect on its transient component.

中文翻译：

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非理想水深的海浪区涡流场和跨岸交换模拟

来自加州中部2017年内架动力学实验（ISDE）的X波段雷达观测结果显示，在相对笔直的海岸线上，沿岸线变化的测深法存在多个持续和脉动的裂隙水流。尽管过去的研究已经评估了沿海均匀海滩上瞬态裂变电流的特性，但对于现实波浪条件下非均匀海滩上瞬态与稳定裂变电流行为的相对平衡仍然知之甚少。在这里，是一个相分辨的Boussinesq型波动模型（funwaveC）用于评估沿岸变化的测深法和入射条件在控制平均和瞬态冲浪区涡度和速度场及其对冲浪区交换的影响中的作用。该模型模拟了从ISDE观测中选择的波浪条件，并利用了从ISDE雷达观测估计的沿岸变化的测深法和统一的测深法。结果表明，可变的测深法显着增加了沿岸和按时间平均的动能，但这种增加主要是由于平均环流模式引起的站立分量增加，而瞬态分量只有很小的变化。在大空间尺度（> 100 m）下，可变的测深法还增加了海浪区涡旋的频谱能量和强迫时间平均涡旋。波的方向扩展对沿岸和时间平均的涡旋以及在较小的空间尺度（<100 m）上对海浪带涡度和强迫涡旋的频谱能量有很大的影响。在存在方向性扩展波场的情况下，沿岸变化的测深法会略微增加总交换速度，但对其瞬变分量影响很小。