中尺度涡对南海北部全日内潮传播影响的数值模拟研究

Numerical Simulation of Mesoscale Eddies’Effect on Diurnal Internal Tide Propagation in the Northern South China Sea

基于潮汐-环流耦合的FVCOM数值模式,本文以南海北部全日内潮为例探究了中尺度涡对内潮传播的影响。分析结果表明,暖涡和冷涡分别导致全日内潮向西北和西南方向折射,能通量方向最大变化可达40°;全日内潮能通量大小在子午向呈现反相位变化,在暖涡南部(冷涡北部)边缘显著减小,而在暖涡北部(冷涡南部)边缘明显增大,最大变化幅度达25%;在暖涡南部和冷涡北部,西向背景流导致全日内潮传播相速度分别加快0.7和0.3 m/s,进而引起内潮波峰线向西凸起弯曲。本研究结果对深化理解多尺度背景下的南海北部内波和深海混合时空变化特征具有重要意义。

Based on the tide-circulation coupled FVCOM simulation,this study takes the diurnal internal tide in the northern South China Sea(SCS)as an example to examine the influence of mesoscale eddies on the propagation of the internal tide.It is shown that anticyclonic eddies(AEs)and cyclonic eddies(CEs)lead to the north-westward and south-westward refraction of the diurnal internal tide,and the variation of energy flux reaches up to 40°;diurnal internal tide energy flux varies with an opposite phase in the meridional direction,which decreases significantly in the southern(northern)edge of the AE(CE)and increases in the northern(southern)edge of the AE(CE),reaching up to 25%;in the south of the AE and north of the CE,the westward background current causes the diurnal internal tide phase speed to increase by 0.7 and 0.3 m/s,respectively,and then leads to the internal tide wave crest bending westward.The results of this study are of great significance to further understand the temporal and spatial characteristics of internal wave and deep mixing in the northern SCS.