Abstract The Caspian Sea (CS) is the largest enclosed basin in the world, located inside the Eurasian continent in the Northern Hemisphere. Although there have been few studies of the dynamics of the coastal zone in the CS, observations show that oscillations with periods from 2–3 days to 1–3 weeks dominate. These oscillations are presumed to be related to the synoptic variability of direct wind impact and to coastally-trapped waves (CTW). Here, we describe and interpret current meter observations on the continental margins of the southern CS from 2012 to 2014 to identify and characterize CTW there. Time series analysis provides evidence for both remote and locally wind-forced eastward traveling signals with time lags consistent with CTW theory. A wind-forced model with two CTW modes is able to reproduce the structure, amplitudes, and phases of observed alongshore current fluctuations, explaining half of the variance at frequencies less than 1 cpd. Remote forcing effects are present at all times, but are most striking when the local winds are weak, as in summer. The CTW calculations also suggest that the source region for the remote forcing may extend farther north along the west coast of the CS.

中文翻译：

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里海南部大陆架洋流的低频变化

摘要 里海（CS）是世界上最大的封闭盆地，位于北半球欧亚大陆内部。尽管对 CS 中沿海地区动态的研究很少，但观察表明，周期为 2-3 天到 1-3 周的振荡占主导地位。据推测，这些振荡与直接风影响的天气变化和沿海陷波 (CTW) 相关。在这里，我们描述和解释了 2012 年至 2014 年在南部 CS 大陆边缘的电流表观测，以识别和表征那里的 CTW。时间序列分析为具有与 CTW 理论一致的时滞的远程和局部风力东行信号提供了证据。具有两种 CTW 模式的风力模型能够再现结构、振幅、和观察到的沿岸电流波动的相位，解释了频率小于 1 cpd 时的一半方差。远程强迫效应始终存在，但在当地风弱时（如夏季）最为显着。CTW 计算还表明，远程强迫的源区可能沿着 CS 的西海岸向北延伸。