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北太平洋 Rossby 波传播特征及其对台湾以东黑潮影响的研究
时云龙
学位类型博士
导师尹宝树
2017-05-18
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Rossby波 孤立rossby波 中尺度涡 台湾以东 黑潮
摘要黑潮是西北太平洋一支非常重要的西边界流,在北太平洋的海洋经向热输送和气候变化中起着重要的作用。台湾以东黑潮是东海黑潮的源头,其流量的低频
变异会直接影响东海黑潮流域的SST 异常,进而影响我国大气环流和降水。由于台湾以东黑潮流量的变异主要是由大洋内区Rossby 波向西传播到台湾以东海域与
黑潮作用引起的,因此深入研究Rossby 波的传播特征及其如何与黑潮相互作用、如何影响黑潮路径的弯曲和形态以及孤立Rossby 波所携带的大洋内部的水团能否
穿过黑潮进入南海与东海具有重要的理论和实际意义。
本文利用AVISO 与SODA 数据分析了北太平洋Rossby 波的传播特征,结合前人的研究成果,指出了线性Rossby 波理论不能很好地解释的一些观测现象。采
用理论分析与数值模拟相结合的方法在非线性理论框架下讨论了背景流剪切及非线性对Rossby 波传播的影响,从而解释了线性Rossby 波理论所不能很好解释的
大洋中观测到的一些波动现象。得到的主要结论如下:
1. 在非线性Rossby 波理论下,背景流剪切、浮力频率及β 效应是孤立Rossby
波存在的重要因素。孤立Rossby 波具有非频散的性质,波宽与背景流剪切
强度呈反相关;波速大于线性Rossby 波波速,且与振幅、背景流剪切强度
呈正相关,背景流剪切越大,振幅对波速的影响越显著。
2. 高纬度地区的Rossby 波比低纬度地区的传播速度慢,波动也更易维持初始
形状。耗散使Rossby 波的强度、传播速度、总能量与拟能都减小。
3. 背景流剪切δ < 0 时,存在气旋式孤立Rossby 波,其经向结构向北倾斜;背
景流剪切δ > 0 时,存在反气旋式孤立Rossby 波,其经向结构向南倾斜。
4. 孤立Rossby 波具有输运水团的性质,但其所能输运水团的范围不是南北
对称的。反气旋式孤立Rossby 波有利于南侧水团的输运,而气旋式孤立
Rossby 波则有利于北侧水团的输运。
进一步,利用层结流体准地转理论设计了第一斜压模Rossby 波与黑潮相互作
用的高分辨率数值实验,详细讨论了不同类型涡旋的传播特征,及其与台湾以东
黑潮相互作用的三维结构变化特征,以及涡旋所携带的大洋内区水团到达台湾以
东海域的去向问题。主要结论如下:
1. 反气旋式涡旋与气旋式涡旋在β 效应下以第一斜压模Rossby 波波速向西传
播。其中,反气旋式涡旋在向西传播过程中向南偏移,而气旋式涡旋在向西
传波过程中则向北偏移。涡旋的影响深度大约在2000 米左右。
2. 涡旋到达台湾以东海域后,与黑潮相互作用从而改变了黑潮的空间结构,并
使台湾以东黑潮流量发生显著的变化。涡旋与黑潮作用的时间大约持续100
天。
3. 反气旋式涡旋在与黑潮作用过程中并不能越过黑潮到达黑潮西侧,而是沿黑
潮东侧向北流去,到达台湾以东至与那国岛(K1)断面、与那国岛至石垣岛
(K2)断面时,使K1、K2 断面上黑潮主轴先离岸后近岸,同时引起K1 (K2)
断面上黑潮流量先减小(增大) 后增大(减小)。
4. 气旋式涡旋与黑潮作用过程中使黑潮产生大的离岸弯曲,同时该涡旋被卷入
黑潮西侧,而后随黑潮向北流去,使K1、K2 断面上黑潮主轴离岸,同时引
起K1 断面上黑潮流量减小,K2 断面上黑潮流量增大。
5. 反气旋式涡旋所携带大洋内区水团到达台湾以东海域后,600 米以浅部分在
黑潮影响下沿黑潮东侧向北流,进入东海,而600 米以深部分因受黑潮影响
较小,则继续向西传播,通过黑潮底部与吕宋海峡进入南海。
6. 气旋式涡旋所携带大洋内区水团到达台湾以东海域后可以穿过黑潮到达黑潮
西侧,而后在黑潮影响下向北流去。其中300 米以浅的水团越过宜兰海脊后
可以到达东海陆架,300–600 米之间的水团越过宜兰海脊后沿路坡转向东北
不能到达东海陆架,600 米以深的水团受地形影响不能越过宜兰海脊,而是
在到达宜兰海脊之前便流向琉球群岛以东海域。
其他摘要Kuroshio is a very important western boundary current in the Northwest Pacific and
plays an important role in the oceanic ocean thermal transport and climate change in the
North Pacific. The Kuroshio east of Taiwan is the source of the Kuroshio in the East
China Sea. The low frequency variation of the Kuroshio volume transport (KVT) will
directly affect the SST anomaly in the Kuroshio watershed and affect the atmospheric
circulation and precipitation in China. A large number of studies have pointed out that the
variation of KVT in the east of Taiwan is mainly caused by the interaction of Kuroshio and
Rossby waves, which spread from the ocean to the east of Taiwan. So, the study of Rossby
waves propagtion charateristics, how they interact with Kuroshio, how they influence the
curvature and shape of the Kuroshio path, and whether the oceanic water mass carried by
the solitary Rossby waves can pass through the Kuroshio into the South China Sea and
the East China Sea have important theoretical and practical significance.
Based on the AVISO and SODA data, the propagation characteristics of Rossby
waves in the North Pacific are analyzed, and some observational phenomena which can
not be explained by the linear Rossby wave theory are proposed in combination with the
previous research results. By means of theoretical analysis and numerical simulation, the
influence of background flow shear and nonlinearity on the propagation of Rossby waves
are discussed in the framework of nonlinear theory, which explains the observations in the
ocean that can not be explained by linear Rossby wave theory. The main conclusions are
as follows:
1. In the nonlinear Rossby wave theory, background flow shear, buoyancy frequency
and β effect are important factors for the existence of solitary Rossby waves. Solitary
Rossby waves are non-dispersive waves, and the wave width is inversely related
to the flow shear strength; the phase speed of solitary Rossby waves is greater than
the linear Rossby waves; the phase speed is positively correlated with the amplitude
and flow shear strength, and the greater the flow shear is, the more significant the
effect of amplitude on the phase speed.
2. The phase speed of Rossby waves is faster in low latitude than in high latitude.
Dissipation reduces Rossby waves intensity, propagation velocity, total energy and
quasi-energy.
3. For flow shear δ < 0, cyclonic solitary Rossby waves exist and their meridional
structure tilts northward; for flow shear δ > 0, anticyclonic solitary Rossby waves
exist and their meridional structure tilts southward;
4. Solitary waves have the nature of transporting water mass, and the range of water
transport is not north–south symmetry. The anticyclonic solitary Rossby waves favor
the transport of the southern water mass, and the cyclonic solitary Rossby waves
favor the transport of the northern water mass.
Furthermore, by using the stratified fluid quasi-geostrophic theory, the high-resolution
numerical experiments of the interaction between the first mode baroclinic Rossby waves
and the Kuroshio are designed. The propagation characteristics of different types of eddies,
three–dimensional structural variation of the interaction between the eddy and the
Kuroshio in the East of Taiwan, and the flow distribution characteristics of water mass
carried by eddies in the East of Taiwan are discussed in detail. The main conclusions are
as follows:
1. The anticyclone eddy and the cyclonic eddy are propagated westward at the first
baroclinic mode Rossby wave velocity under the influence of β effect, in which the
anticyclonic eddy is shifted southward during the westward propagation process, the
cyclonic eddy is shifted northward during the westward propagation process. The
depth influenced by eddy is about 2000 meters.
2. After the eddy reaches the waters east of Taiwan, the spatial structure of Kuroshio
is changed by the interaction of eddy and Kuroshio, which makes a significant KVT
fluctuations. The eddy and Kuroshio interaction time lasts about 100 days.
3. During the interaction of anticyclonic eddy and Kuroshio, anticyclonic eddy can
not cross the Kuroshio to reach the west side of the Kuroshio, but along the east
side of the Kuroshio flow to the north. When anticyclonic eddy reaching K1、K2
section, the Kuroshio spindle in K1、K2 section first offshore then onshore, while
causing the KVT in K1 (K2) section decreases first (increases) and then increases
(decreases).
4. During the interaction of cyclonic eddy and Kuroshio, cyclone eddy can be involved
to the west side of the Kuroshio, then flow to the north along west side of the Kuroshio, while causing large offshore Kuroshio meandering and low (high) KVT
in K1 (K2) section.
5. When the oceanic water mass carried by anticyclone eddies reach the waters east
of Taiwan, the upper 600 meters water mass flow into East China Sea under the
influence of Kuroshio, and the water mass below 600 meters continue to spread
westward through the bottom of the Kuroshio and Luzon Strait into the South China
Sea due to the weak influence of Kuroshio.
6. When the oceanic water mass carried by cyclone eddies reach the waters east of
Taiwan, the water mass can go through the Kuroshio to the west side of the Kuroshio,
and then flow northward under the influence of the Kuroshio. The upper 300 meters
water mass can flow over the Ilan Ridge to reach the East China Sea shelf; the
water mass between 300–600 meters flow northwestward along the north coast of
Taiwan after passing the Ilan Ridge, which can not reach the East China Sea shelf;
the water mass below 600 meters can not flow over Ilan Ridge due to the topographic
influence, but flow to the east of Ryukyu Islands waters before reaching the Ilan
Ridge.
学科领域物理海洋学
语种中文
文献类型学位论文
条目标识符http://ir.qdio.ac.cn/handle/337002/136571
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
推荐引用方式
GB/T 7714
时云龙. 北太平洋 Rossby 波传播特征及其对台湾以东黑潮影响的研究[D]. 北京. 中国科学院大学,2017.
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