弱地形上内潮生成问题——Ⅱ.粗糙地形情况下水深对内潮能通量的影响

前人在讨论水深对内潮能通量影响的时候得出结论:有限深海洋中海面对内潮的反射使得正压潮向内潮的能量转化相比较无限深海的情况显著降低,对于选定的地形,在无限深海假定下得到的能通量是该地形上内潮能通量的上限。鉴于前人所研究的基本上都是平滑的地形,而实际的海洋地形总是比较粗糙的,本文探讨了粗糙地形上内潮能通量随水深的变化。选取了弦函数地形、随机白噪声地形、弦函数地形叠加在高斯地形之上、随机白噪声地形叠加在高斯地形之上和随机白噪声地形与弦函数地形同时叠加在高斯地形之上5种情况进行了研究,发现对于这5种情况,都存在海洋有限深时的能通量大于无限深假定时的能通量,这说明前人得出的"有限深海洋中海面对内潮的反射使得正压潮向内潮的能量转化相比较无限深海的情况显著降低"的结论对于粗糙地形并不适用。

Generation of Internal Tide Under Weak Topography Approximation——Ⅱ. Influence of Water Depth on Energy Flux of Internal Tide Under Rough Topography Conditions

Previous studies have drawn a conclusion on the effect of water depth on internal tide energy flux that the reflection of internal tide from the sea surface in the ocean of finite depth greatly reduces the transfer of energy flux from barotropic tide to internal tide,that is,for a given topography,the energy flux obtained on the assumption of unlimited depth ocean is the upper limit for the energy flux of internal tide generated over a given topography.The previous studies were concerned mainly with the smooth topography,and the real oceanic topography is always relatively rough,so this study explores the variations in energy flux of internal tide generated over a rough topography with water depth.Five rough topographies are chosen for this study,and they are cosine topography,white noise topography,the Gaussian seamount superimposed by a small-scaled cosine topography,the Gaussian seamount superimposed by a small-scaled white noise topography and the Gaussian seamount superimposed by a small-scaled white noise topography and a small-scaled cosine topography.It is shown from the study results that the energy fluxes of internal tide generated over the five rough topographies in the finite depth ocean can be greater than those obtained on the assumption of unlimited depth ocean.Therefore,the previous conclusion that the energy flux obtained on the assumption of unlimited depth ocean is the upper limit for the energy flux of internal tide generated over a given topography is not applicable to the rough topography although the conclusion is correct for the smooth topography.