The effects of wind forcing and Earth’s rotation on the transport processes in Lake Garda (Italy) are investigated for the first time under different thermal stratification conditions and typical diurnal wind cycles. Numerical simulations are performed by means of a modeling chain composed of a meteorological (WRF) and a hydrodynamic (Delft3D) model. Transport processes are studied through the combined analysis of the residual (time averaged) flow field and the trajectories of Lagrangian particles. Results show that strong currents develop in winter under the forcing of synoptic northerly Fohn winds, especially in the elongated northern region, where winds are channeled by the steep orography. Significant water volumes are displaced laterally by Ekman transport, producing intense downwelling and upwelling along the steep shores. Instead summer patterns are controlled by the diurnal cycle of local breezes, alternately blowing along the main axis of the lake. The resulting circulation reveals counterclockwise gyres in the northern part, driven by the alternating wind direction and affected by Coriolis force. The analysis suggests that complex circulations can develop in lakes with relatively simple geometries, like the narrow trunk region of Lake Garda, where the effect of Earth’s rotation unexpectedly influences the transport patterns.

中文翻译：

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风变率和地球自转作为深而细长的亚高山湖泊中的运输驱动因素：加尔达湖的案例

在不同的热分层条件和典型的昼夜风循环下，首次研究了风力和地球自转对加尔达湖（意大利）运输过程的影响。数值模拟是通过由气象 (WRF) 和流体动力学 (Delft3D) 模型组成的建模链进行的。通过对残余（时间平均）流场和拉格朗日粒子轨迹的组合分析来研究传输过程。结果表明，冬季在天气向北的冯氏风的推动下形成了强大的洋流，特别是在狭长的北部地区，那里的风是由陡峭的地形引导的。大量的水被 Ekman 运输横向转移，沿着陡峭的海岸产生强烈的下流和上流。相反，夏季模式由当地微风的昼夜循环控制，沿湖的主轴交替吹动。由此产生的环流揭示了北部的逆时针环流，由交替风向驱动并受科里奥利力影响。分析表明，复杂的环流可以在几何形状相对简单的湖泊中形成，例如加尔达湖狭窄的主干区域，地球自转的影响出乎意料地影响了运输模式。