Surf zone eddies coupled with rip current morphology
Surf zone eddies coupled with rip current morphology
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冲浪区涡流与离岸流形态耦合
DOI：
10.1029/2003jc002083
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发表时间：
2004
影响因子：
--
通讯作者：
T. Stanton
中科院分区：
文献类型：
--
作者：
J. MacMahan;A. Reniers;E. Thornton;T. Stanton
[1]在加州蒙特雷湾沙城的一个由具有准周期性（约125 m）下切水道的岸连浅滩组成的海滩上观测到了高能甚低频（VLF;频率<0.004 Hz）碎波带涡旋（SZEs）。入射波主要由海岸正常窄带膨胀波。SZES位于重力区域外的沿岸波数，ky，在甚低频波段内间隔，并没有出现在较高的频段。SZEs在碎波带（连接海岸的浅滩和裂流通道）内具有显著的强度（Urms，VLF <0.25 m/s）和恒定的强度，并在近海迅速下降。沿岸和跨岸SZE速度的变化幅度相似。VLF SZE速度并没有被迫由VLF表面海拔，并没有很好的相关性与裂流（r2 = 0.18）。有迹象表明，SZEs与波浪强迫有关，SZEs与传入的海浪波高（r2 = 0.49）统计相关。F-ky谱估计说明了裂流通道间距和SZE跨岸速度（ky = ±0.008 m−1）之间的强关系，以及SZE沿岸速度变化最小（ky = 0 m−1）。数据分析表明，SZE不仅仅是不稳定离岸流急流的不稳定性。一个简单的概念模型表明，SZE的f-ky谱可以解释为整个裂流环流细胞振荡主要在跨海岸和轻微的沿海岸。
[1] Energetic very low frequency (VLF; frequencies <0.004 Hz) surf zone eddies (SZEs) were observed on a beach composed of shore-connected shoals with quasi-periodic (∼125 m) incised rip channels at Sand City, Monterey Bay, California. Incident waves consisted of predominantly shore-normal narrow-banded swell waves. SZEs were located outside the gravity region in alongshore wave number, ky, spaced within the VLF band, and did not appear to exist in higher-frequency bands. The SZEs were significant (Urms,VLF ∼ 0.25 m/s) and constant in intensity within the surf zone (shore-connected shoals and rip channels) and rapidly decreased offshore. The alongshore and cross-shore SZE velocity variances were similar in magnitude. VLF SZE velocities were not forced by VLF surface elevations and were not well correlated with rip current flows (r2 = 0.18). There is an indication that the SZEs were related to wave forcing, with the SZEs statistically correlated with incoming sea-swell wave height (r2 = 0.49). F-ky spectral estimates illustrate a strong relationship between rip channel spacing and SZE cross-shore velocities (ky = ±0.008 m−1) and minimal SZE alongshore velocity variation (ky = 0 m−1). Data analysis suggests that the SZEs are not simply instabilities of an unstable rip current jet. A simple conceptual model suggests that SZE f-ky spectra can be explained by the entire rip current circulation cells oscillating predominantly in the cross shore and slightly in the alongshore.