基于数值模式的南海北部深层内潮季节变化特征分析

Numerical simulation of internal tides seasonal variations in the deep northern South China Sea

本文基于MITgcm非静力数值模式,采用实际地形、层结和潮流强迫,开展南海北部内潮数值模拟敏感性试验,分析夏冬两个季节南海北部深层内潮的差异。结果显示在南海北部深层,冬季K1和M2内潮流速振幅比夏季强10.1%和44.7%。垂向模态分析结果进一步表明,尽管南海北部深层冬季第一模态内潮动能密度比夏季低15.5%,但第二和第三模态内潮则是冬季比夏季高约25.1%和33.2%,导致冬季深层流速的垂向剪切大于夏季,表明冬季较强的高模态内潮可能是冬季南海深层强混合的一个原因。

Based on the Massachusetts Institute of Technology General Circulation Model, the numerical simulation of the internal tide in the northern South China Sea （SCS） is carried out by using the actual bathymetry, stratifica- tion and tidal current force. The differences of the internal tide in the northern South China Sea during the two sea- sons are analyzed. The results show that the velocity in the K1 and M2 is 10.1% and 44.7% stronger than that in the summer. The results of the vertical modal analysis show that although the tidal kinetic energy density in the first modal is 15.5% lower in winter than that in summer, the second and third modal tides are about 25. 1% and 33. 2% higher. These high-mode tides may lead to intense vertical shear in the deep basin of SCS in winter, indica- ting that the stronger high-mode tide may be one of the reasons for the intense mixing of the deep SCS in winter.