吕宋海峡M_2内潮生成与传播数值模拟研究

Numerical Simulation Study of M2 Internal Tides Generation and Propagation in the Luzon Strait

本文在z坐标海洋数值模式HAMSOM中引入了内潮黏性项(Internal-tide viscosity term),将之运用到吕宋海峡M2内潮的生成与传播过程的数值模拟研究。研究结果表明:(1)在250 m以浅,吕宋海峡产生的M2内潮振幅于温跃层处最大,岛坡附近的内潮明显强于别处,且最大振幅可达到40 m左右;(2)M2内潮的生成源主要集中在伊特巴亚岛西北、巴丹岛西南以及巴布延群岛西北的岛坡;(3)海峡产生的M2内潮向东西2个方向传播。巴丹岛以西的西向能量在吕宋海沟斜向下传播,在到达恒春海脊附近发生反射返回海面,到达海面后再次反射回海底,在此过程中,有高模态的内潮被激发,不同模态间有相消干涉的现象产生。西传的内潮能量分为2支进入南海,产生于巴布延群岛西北的能量分支直接向西南折转进入南海海盆,而产生于伊特巴亚岛和巴丹岛岛坡附近的主要能量则以束状向南海陆架传播,在到达118°E后部分能量折向西南的海盆,其余的能量则沿西北方向传入中国近岸,陆架陆坡地形起着重要的耗散作用。伊特巴亚岛西北有最大的能量产生,向东北传入太平洋。在122°E以东,能量主要以束状向东南传入太平洋。

Based on the z-coordinate model HAMSOM,we introduced the internal-tide viscosity term and applied the modified model to numerically investigate the M2 internal tides in the Luzon strait for its generation and propagation.The results show that：（1） The amplitude upper 250 m of the M2 internal tides generated in the Luzon strait is maximum at the thermocline.The internal tides near island slopes are stronger than those in other areas and the maximum amplitude there is about 40 m.（2） The island slope areas in the northwest of Itbayat island,the southwest of Batan islands and the northwest of Babuyan islands are the generation source areas of the M2 internal tides.（3） The M2 internal tides generated in the strait propagate eastward and westward.The westward internal tide energy at the west of Batan islands travels slantingly downwards and returns to seasurface after the reflection near the Heng-Chun Ridge,which returns to bottom after the second reflection on the seasurface.In this progress,high mode internal tides are stimulated and different modes appear the destructive interference phenomenon.The westward energy divides into two branches,one branch generated in the northwest of Babuyan Islands directly turns into the sea basin,the other branch generated in the island slope areas of Itbayat island and Batan islands travels to the South China Sea shelf like a beam.When arriving in 118°E,a part of this energy turns into the sea basin,and the rest part travels northwest to coast area of China.Continental shelf and slopes have an important function of energy dissipation.The highest internal tide energy in the Luzon Strait is at the northwest of Itbayat island,which propagates northeastwards to the Pacific Ocean.And in the east of 122°E,the eastward internal tide energy propagates southeastwards to the Pacific Ocean like a beam.