IOCAS-IR  > 海洋环流与波动重点实验室
吕宋海峡内潮生成与传播的数值模拟研究
刘昆
学位类型博士
导师尹宝树
2016-05-16
学位授予单位中国科学院大学
学位授予地点北京
学位专业物理海洋学
关键词吕宋海峡 内潮 数值模拟 Roms
摘要摘 要
 
内潮是一种潮频率的内重力波,对全球海洋中的能量分配与混合过程有至关重要的作用。吕宋海峡作为连接西太平洋和南海的主要通道,是全球内潮生成最为活跃的区域之一,高度计观测表明吕宋海峡内潮能够从源区辐射并传播上千公里。本文基于ROMS(Regional Ocean Model System)对吕宋海峡内潮的生成与传播进行了模拟研究,分析了吕宋海峡内潮的生成过程及能量收支,探讨了吕宋海峡内潮在西太平洋和南海的长距离传播及传播过程中的变化规律,并对全日和半日内潮在传播过程中的能量转化和混合过程进行了深入分析,得出一些有新意的结论如下:
1、模拟得到了西太平洋和南海三维高分辨率的内潮场,并根据模拟结果计算了吕宋海峡内潮能量收支。在吕宋海峡约有17.3 GW(12.3 GW)的能量从M2(K1)正压潮转化为内潮,约39%在局地耗散掉,其余的部分辐射进入西太平洋和南海,其中5.0 GW(3.7 GW)的斜压能量向东辐射进入西太平洋,5.6 GW(3.8 GW)的斜压能量向西辐射进入南海。
2、低模态内潮能够从吕宋海峡向远处辐射并进行长距离传播,全日和半日内潮在传播过程中表现出不同特征。西向辐射的M2和K1内潮都能穿过南海海盆到达越南沿岸。其中M2内潮有明显的南北不对称特征,北部分支的强度(4.1 GW)约为南部分支(1.9 GW)的两倍。东向辐射的M2内潮在西太平洋传播可超过1500 km,K1内潮超过2000 km。在长距离传播过程中,M2内潮传播方向基本保持不变,而K1和O1内潮逐渐向赤道方向弯曲。相对于M2内潮,传播过程中K1内潮能量衰减更慢。
南海中吕宋海峡和东沙群岛附近的大陆坡区域是M2和K1内潮能量主要的汇。西太平洋中内潮的长距离传播使得耗散遍布模拟海域,其中K1内潮在低纬度的耗散更强,这主要是传播过程中K1内潮向赤道方向弯曲所导致。潮致混合使得源区附近的垂向扩散系数提高了近两个量级(约为),内潮在传播过程中的耗散使得开阔海域的垂向混合也有所加强。M2内潮引起的混合比K1内潮更强,尤其在双海脊与大陆架之间的区域。
其他摘要 Internal tides are internal gravity waves with tidal frequencies, they play a significant role in energy distribution and mixing. Connecting both the Western Pacific and South China Sea,Luzon Strait is one of the most energetic areas generating internal tides. Observational evidence show that internal tides radiate from Luzon Strait and propagate thousands of kilometers. In this paper ROMS (Regional Ocean Model System) is used to simulate internal tides in the Luzon Strait, we employ  three-dimensional numerical simulations with real bathymetry and perform detailed analyses of internal tides energetics and dynamics to understand how they are generated in the Luzon Strait and how they propagate in the Western Pacific and South China Sea. The simulated results indicate that:
1. Three-dimensional high-resolution internal tides field of both Western Pacific and South China Sea was reproduced. In the Luzon Strait 17.3 GW (12.3 GW) of M2 (K1) barotropic energy is converted to baroclinic part. Among which 39% of the converted baroclinic energy dissipate locally, and the rest of it radiate into both South China Sea and Western Pacific. For M2 (K1) internal tides, 5.6 GW (3.8 GW) of baroclinic energy radiated into South China Sea, and 5.0 GW (3.7 GW) radiated into Western Pacific.
2. Low-mode diurnal and semidiurnal internal tides generated at Luzon Strait can propagate a long distance from generation site, but they shows different pattern and variation during propagation. Both diurnal and semidiurnal internal tides can propagate through the South China Sea arriving at the coast of Vietnam. M2 internal tides from Luzon Strait radiate into the South China Sea into two beams and perform north-south asymmetry pattern, the intensity of north beam (4.1 GW) is about twice the south one (1.9 GW). M2 (K1) internal tides originating in the Luzon Strait can propagate over 1500 (2000) km in the Western Pacific. Diurnal internal tides with lower frequency are more affected by the earth’s rotation. For M2 internal tides the propagation direction remains nearly unchanged, but diurnal internal tides (K1 and O1) bend toward the Equator during propagation. K1 internal tides are found to maintain a better strength than M2 internal tides during long-range propagation.
3. A great deal of energy radiate from the generation sites to far-field due to internal tides propagation, resulting in a broad spacial distribution of dissipation. Luzon Strait and regions around Dongsha Island are important sinks for baroclinic energy in the South China Sea. In the Western Pacific K1 internal tides lose more energy in low latitudes, the possible reasons may be that K1 internal tides bend toward the Equator during propagation. The diapycnal mixing around generation sites and far-field are enhanced due to tidal mixing. The diapycnal mixing elevation induced by M2 internal tides is stronger than K1 internal tides, especially in the regions between Luzon Strait and the continental shelf.
语种中文
文献类型学位论文
条目标识符http://ir.qdio.ac.cn/handle/337002/112530
专题海洋环流与波动重点实验室
作者单位中国科学院海洋研究所 海洋环流与波动重点实验室
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刘昆. 吕宋海峡内潮生成与传播的数值模拟研究[D]. 北京. 中国科学院大学,2016.
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