Abstract The Caspian Sea water dynamics on the boundary of its northern and central basins is considered. A high-resolution numerical model (with a grid step of ~2 km) has been used to reproduce the mesoscale structure of currents. The results of two experiments are presented: a realistic reconstruction of the sea circulation in 2003 and an idealized one with an artificial forcing. The realistic calculation considers the water exchange between the two basins, which occurs primarily due to coastal jet currents near Tyub-Karagan Peninsula in the east and near the Agrakhan Peninsula in the west. The formation and evolution of these currents under various synoptic situations are analyzed, and their flow rates are quantitatively estimated. The effect of contrasting water intrusions caused by these currents on the salinity field in both basins with highly different haline regimes is estimated. In particular, the western current (WC) is shown to increase the sea surface salinity (SSS) in the Northern Caspian and decrease its value in the Middle Caspian by almost 1–2 psu/year. The water exchange in the east is asymmetric: the northern current increases salinity in the northern basin by 2–3 psu/year, while the southern current decreases the average SSS in the central basin by only around 0.5 psu/year; in this case, the southern current occurs stably only in June and July. The idealized experiment simulates the Caspian water dynamics for winds of various points: from 0° to 350° with a step of 10°. The flow rates of both western and eastern currents have a sinusoidal dependence on the wind direction: their maxima are reached with winds of 40° and 220° points for the WC and with 120° and 300° points for the eastern current (EC). This study also analyzes the establishment of quasi-steady-state sea circulation at a constant wind.

中文翻译：

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里海北部和中部之间的水交换

摘要 考虑了里海北部和中部盆地边界上的海水动力学。高分辨率数值模型（网格步长约为 2 公里）已被用于再现电流的中尺度结构。提供了两个实验的结果：2003 年海洋环流的现实重建和具有人工强迫的理想化的重建。实际计算考虑了两个盆地之间的水交换，这主要是由于东部靠近 Tyub-Karagan 半岛和西部靠近 Agrakhan 半岛的海岸急流而发生的。分析了各种天气情况下这些洋流的形成和演变，并定量估计了它们的流速。估计了由这些洋流引起的对比性水侵入对盐度高度不同的两个盆地的盐度场的影响。特别是，西洋流 (WC) 被证明会增加里海北部的海面盐度 (SSS)，并将其在里海中部的值降低近 1-2 psu/年。东部的水交换是不对称的：北流使北部盆地的盐度增加 2-3 psu/年，而南流使中部盆地的平均 SSS 降低仅 0.5 psu/年左右；在这种情况下，南流仅在六月和七月稳定出现。理想化的实验模拟了不同点风的里海水动力学：从 0° 到 350°，步长为 10°。西洋流和东洋流的流速都与风向呈正弦关系：西洋流在 40° 和 220° 点处达到它们的最大值，而东洋流 (EC) 在 120° 和 300° 点处达到它们的最大值。本研究还分析了恒定风下准稳态海洋环流的建立。