Wind variability and Earth's rotation as drivers of transport in a deep, elongated subalpine lake: The case of Lake Garda
Wind variability and Earth's rotation as drivers of transport in a deep, elongated subalpine lake: The case of Lake Garda
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DOI：
10.4081/jlimnol.2018.1814
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发表时间：
2018-01-01
影响因子：
1.6
通讯作者：
Toffolon, Marco
中科院分区：
文献类型：
--
作者：
Amadori, Marina;Piccolroaz, Sebastian;Toffolon, Marco
首次在不同的热分层条件和典型的日风循环下研究了风力强迫和地球自转对加尔达湖（意大利）输送过程的影响。数值模拟是通过由气象 (WRF) 和水动力 (Delft3D) 模型组成的建模链来执行的。通过残余（时间平均）流场和拉格朗日粒子轨迹的组合分析来研究输运过程。结果表明，在天气偏北希姆风的强迫下，冬季会形成强大的洋流，特别是在狭长的北部地区，那里的风被陡峭的地形引导。大量的水量被埃克曼运输横向转移，沿着陡峭的海岸产生强烈的下降流和上升流。相反，夏季模式是由当地微风的昼夜循环控制的，微风沿着湖的主轴线交替吹动。由此产生的环流在北部地区呈现逆时针环流，受到交替风向的驱动并受到科里奥利力的影响。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干区，地球自转的影响意外地影响了运输模式。
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 Him 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.