南海北部不同涡旋对内潮的影响

南海北部吕宋海峡是内潮最为活跃的区域之一, 且涡旋种类繁多, 不同特性的涡旋对内潮的影响不同。基于近岸与区域海洋共同模式(coastal and regional ocean community model, CROCO), 模拟探究理想涡旋存在时, 涡旋位置、极性、峰值流速和半径对内潮的影响。结果表明: 涡旋位置是影响内潮的直接因素, 位于涡旋区域内的内潮是主要影响对象, 涡旋中心以西内潮方向变化的角度是以东的3倍。气旋涡和反气旋涡分别使潮能通量的方向向南和向北偏转,最大偏转角度超过12°, 当涡旋所致背景流与内潮传播方向一致时, 内潮群速度增强, 反之减弱。涡旋对内潮的影响范围和幅度随着涡旋的半径和峰值流速的增大而变大。当涡旋峰值速度变大时, 反气旋涡心以北的潮能通量增长量超过15 kW/m。当涡旋半径增大时, 涡旋峰值速度的位置发生变化, 涡旋的峰值流速和半径共同影响潮能通量水平分布结构, 使其呈现纬向单峰或多峰结构。

INFLUENCE OF DIFFERENT EDDIES ON INTERNAL TIDES IN NORTHERN SOUTH CHINA SEA

The Luzon Strait, located in the northern region of the South China Sea, stands out as one of the most active areas for internal tides, characterized by a variety of eddies. Different characteristics of these eddies generate various effects on internal tides. Using the CROCO numerical model, we simulated the impact of the eddy position, polarity, peak velocity, and radius on internal tides in the presence of an ideal eddy. Results indicate that the position of eddy is a direct factor influencing the internal tide, and the internal tide within the eddy region serves as the primary object of influence. The angle of change in direction west of the eddy center is three times that in the east, with a maximum deflection angle exceeding 12°. When the background flow caused by the eddy is in the same direction as the internal tide, the internal tide group velocity increases, and vice versa, it weakens. The influence range and amplitude of the eddy increase with the increase of the eddy radius and peak velocity. When the peak eddy velocity increases, the tidal energy flux north of the eddy center could increase by more than 15 kW/m. When the eddy radius increases, the position of the peak velocity of the eddy changes, and the peak velocity and radius of the eddy affect the horizontal distribution structure of the tidal energy flux, showing a zonal single-peak or multi-peak structure.