IOCAS-IR  > 海洋环流与波动重点实验室
印度尼西亚海域中尺度涡的时空分布特征与机制研究
Alternative TitleSpatiotemporal Characteristics and Driving Mechanisms of Mesoscale Eddies in the Indonesian Seas
郝占久
Subtype博士
Thesis Advisor徐振华
2024-05-20
Degree Grantor中国科学院大学
Place of Conferral中国科学院海洋研究所
Degree Name理学博士
Degree Discipline物理海洋学
Keyword印尼海 中尺度涡 涡动能 西边界流 季风
Abstract

中尺度涡是海洋中普遍存在的一种单体运动现象,是海洋物质输运的重要载体和海洋多尺度能量串级的关键环节。卫星高度计的发展极大地促进了海洋学界对中尺度涡的认识,特别是卫星高度计逐日数据资料的出现将研究视野由中高纬度海域拓展至低纬度海域。然而,以往的诸多研究多关注赤道附近的开阔海域,对于赤道边缘海的中尺度涡仍缺乏系统性认识。印度尼西亚海域(简称印尼海)是赤道太平洋西边界最大的边缘海,亦是衔接太平洋与印度洋的重要洋际通道。独特的多连通群岛地形、复杂的环流结构以及强烈的海气相互作用使得该区域存在丰富的中尺度涡旋活动。因此,全面理解该区域的中尺度涡对印尼海区域海洋学意义重大,同时有利于填补全球中尺度涡拼图在赤道边缘海的空白。

本文基于卫星高度计逐日数据,利用涡旋自动识别与追踪算法,揭示了印尼海中尺度涡的空间分布与季节变化特征。印尼海中尺度涡旋的典型振幅和半径分别为2-6 cm50-160 km。该区域中尺度涡呈现出与低纬度开阔海域相似的特征:生命周期以10-30天为主、非线性程度较中高纬海区涡旋略低、以6-10 cm/s(小于Rossby波的相速度)向西迁移并伴有微弱的经向迁移。四个大而深的海盆是该区域中尺度涡的热点区域,即苏禄海、苏拉威西海、马鲁古海和班达海。其中,苏拉威西海的涡旋能量最强、非线性程度最高、生命周期最长。各海盆内涡旋特性基本呈现出海盆内部大、近岸区域小的分布特征。不同海盆的涡旋展现了迥异的季节变化特征,而各海盆内部气旋涡与反气旋涡的涡旋特性尤其是形心纬度位置亦呈现出相反的季节变化。结合BRAN再分析资料(Bluelink Reanalysis),本文进一步发现背景流正压不稳定与斜压不稳定过程对于不同海盆涡旋生成事件的主导作用存在显著差异。

基于一套准全球涡分辨的海洋通用环流模式(Ocean Forecasting Australian Model version 3, OFAM3)输出产品和涡动能收支分析方法,本文进一步研究了两个典型海盆(班达海和苏拉威西海)涡动能的时间变异规律及其驱动机制,探讨了海盆内部涡动能水平与不同尺度动力过程存在的联系。获得以下科学认识:

1)班达海涡动能呈现出与季风和印度尼西亚贯穿流(Indonesian Throughflow, ITF)高度相关的季节性空间分布特征,即在西北季风和东南季风盛行期间分别在ITF西分支与东分支路径上存在涡动能高值区。风应力做功输入和背景流正压不稳定过程共同控制了班达海涡动能强区的季节变化,其中风应力做功输入占据主导地位。涡动能收支分析表明,风应力做功输入、背景流正压不稳定与斜压不稳定过程分别贡献了班达海涡动能强区能量来源的66%23%11%,而涡动能主要通过水平压力做功过程再分布至其它区域以及被耗散过程所消耗。此外,班达海不同季节的涡动能高值区对应了不同的气旋涡与反气旋涡生成事件,MJOMadden-Julian Oscillation)诱导的西风爆发事件以及ITF导致的岛屿尾涡效应是这些典型涡旋事件的驱动因子。

2)苏拉威西海涡动能呈现出显著的年际变化特征,主要受到棉兰老流入侵苏拉威西海过程的调控。棉兰老流入侵流量在年际时间尺度上的波动通过改变苏拉威西海背景流的水平剪切程度进而影响背景流动能向涡动能的正压转化过程,最终导致苏拉威西海涡动能在年际时间尺度上存在响应。本文进一步发现,棉兰老流入侵过程受到赤道太平洋的中尺度涡以及两支西边界流——棉兰老流与新几内亚沿岸流和新几内亚沿岸潜流的调控。两支西边界流相对强度的变化影响着棉兰老流的入侵流量,同时位于苏拉威西海东侧的气旋涡/反气旋涡亦会促进/抑制棉兰老流入侵苏拉威西海。

Other Abstract

Mesoscale eddies are a ubiquitous monomeric dynamical phenomenon in the ocean, also serving as the important carriers of marine material transport and the key bridges of oceanic multiscale energy cascade. The advancement of satellite altimeters has greatly promoted the understanding of mesoscale eddies within oceanographic community, especially with the availability of daily satellite altimetric products that have been extending research focus from middle and high latitudes to low latitudes. However, previous studies have predominantly focused on the open ocean near the equator, leaving a significant knowledge gap regarding the systematic understanding of mesoscale eddies within the equatorial marginal seas. The Indonesian seas, the largest marginal sea located at the western boundary of the Equatorial Pacific, play a pivotal role as a vital interoceanic passage, facilitating connectivity between the Pacific Ocean and the Indian Ocean. The distinctive multi-connected archipelagic topography, intricate circulation pattern, and robust air-sea interaction within this region foster prolific mesoscale eddy activities. Hence, a comprehensive understanding of mesoscale eddies within this region holds profound significance for the regional oceanography of the Indonesian seas, and is conducive to filling the gap in the equatorial marginal sea within the global picture of mesoscale eddies.

This study utilizes daily satellite altimetric data to unveil the spatial distribution and seasonal variations of mesoscale eddies within the Indonesian seas, employing the automatic eddy identification and tracking algorithm. Typical amplitudes and radii of mesoscale eddies within the Indonesian seas range from 2 to 6 centimeters and 50 to 160 kilometers, respectively. In this region, mesoscale eddies exhibit similar characteristics to those observed in the open ocean at low latitudes: with lifespans primarily ranging from 10 to 30 days, displaying a slightly weaker nonlinearity than that documented in middle and high latitudes. Additionally, these eddies demonstrate a westward migration at speeds ranging from 6 to 10 cm/s (lower than the phase speed of Rossby waves), often accompanied by subtle meridional movement. Four large and deep basins are the hotspots of mesoscale eddies in this region, namely the Sulu Sea, Sulawesi Sea, Maluku Sea, and Banda Sea. Notably, the most energetic, nonlinear, and longevous eddies are observed in the Sulawesi Sea. The characteristics of eddies within each basin fundamentally exhibit a discernible pattern, with larger and more energetic eddies predominating in the interior basin, contrasted by smaller and less energetic eddies found in nearshore regions. The eddies within distinct basins exhibit diverse seasonal cycles, with cyclonic and anticyclonic eddies in each basin displaying opposite seasonal variations in their properties, especially evident in the eddy centroid latitude. Combined with the Bluelink Reanalysis product, it is further found that the dominant role of barotropic instability and baroclinic instability of background currents for eddy generation events across various basins presents pronounced disparities.

Drawing upon the outputs derived from a near-global and eddy-resolving ocean general circulation model (Ocean Forecasting Australian Model version 3, OFAM3) and employing the eddy kinetic energy (EKE) budget analysis, this study delves deeper into the temporal EKE variability and its associated mechanisms within two typical basins: the Banda Sea and Sulawesi Sea. Moreover, this study also investigates the modulations of various dynamic processes at different scales to the EKE levels within these two basins, yielding the following scientific insights:

First, the EKE in the Banda Sea exhibits spatial pattern that are highly correlated with the monsoon and the Indonesian Throughflow (ITF), that is, during the prevailing northwest/southeast monsoon, there is a high-value area of EKE along the western/eastern pathway of ITF. The seasonal EKE variations in the strong EKE region within the Banda Sea is synergistically governed by the wind power input and barotropic instability of background currents, with the dominant role of wind power input. The EKE budget analysis shows that the wind power input, the barotropic instability and baroclinic instability of background currents respectively account for 66%, 23%, and 11% of the energy sources within the strong EKE region of the Banda Sea. Meanwhile, EKE is mainly redistributed to adjacent regions through the horizontal pressure work and consumed by the dissipation. Furthermore, the high-value areas of EKE in the Banda Sea during different prevailing monsoons correspond to different typical cyclonic and anticyclonic eddy generation events. Notably, the west wind bursts promoted by Madden-Julian Oscillation and the island wake effect induced by ITF are the drivers of these typical eddy events.

Second, the EKE in the Sulawesi Sea displays remarkable interannual variability, primarily controlled by the intrusion of the Mindanao Current (MC) into the Sulawesi Sea. The interannual fluctuation of the MC intrusion transport modulates the barotropic conversion from kinetic energy of background flow to EKE by strengthening or weakening the horizontal shear of the background flow in the Sulawesi Sea, and finally leads to the interannual response of the EKE in the Sulawesi Sea. This study also found the modulation of mesoscale eddies and two western boundary currents in the Equatorial Pacific, that is, MC and New Guinea Coastal Current and New Guinea Coastal Undercurrent, on the MC intrusion into the Sulawesi Sea. The changes of relative intensity between these two western boundary currents lead to the interannual variations of MC intrusion transport. In addition, the cyclonic/anticyclonic eddies east of the Sulawesi Sea can also facilitate/depress the MC intrusion into the Sulawesi Sea.

Subject Area物理海洋学
MOST Discipline Catalogue理学::海洋科学
Pages122
Language中文
Table of Contents

1 绪论............................................................................................................................ 1

1.1 研究背景及意义............................................................................................................ 1

1.2 研究现状........................................................................................................................ 4

1.2.1 全球海洋中尺度涡研究进展................................................................................... 5

1.2.2 低纬度海区中尺度涡研究进展............................................................................... 8

1.2.3 印度尼西亚海中尺度涡研究进展......................................................................... 11

1.3 科学问题与研究内容................................................................................................. 14

2 数据与方法............................................................................................................. 17

2.1 研究数据...................................................................................................................... 17

2.1.1 卫星高度计观测数据............................................................................................. 17

2.1.2 OFAM3模式输出产品........................................................................................... 17

2.1.3 BRAN再分析资料.................................................................................................. 20

2.1.4 其它数据.................................................................................................................. 22

2.2 研究方法...................................................................................................................... 23

2.2.1 涡旋自动识别与追踪算法..................................................................................... 23

2.2.2 涡动能收支分析...................................................................................................... 26

3 印尼海中尺度涡的空间分布与季节变化特征.................................................. 29

3.1 引言.............................................................................................................................. 29

3.2 空间分布特征............................................................................................................. 29

3.2.1 涡旋的生成与消亡................................................................................................. 30

3.2.2 涡旋迁移规律与非线性程度................................................................................. 32

3.2.3 涡旋动力特征.......................................................................................................... 34

3.3 季节变化特征............................................................................................................. 37

3.3.1 苏禄海...................................................................................................................... 37

3.3.2 苏拉威西海.............................................................................................................. 38

3.3.3 马鲁古海.................................................................................................................. 39

3.3.4 班达海...................................................................................................................... 40

3.4 涡旋事件的生成机制................................................................................................. 41

3.5 讨论.............................................................................................................................. 44

3.6 本章小结...................................................................................................................... 45

4 班达海涡动能季节变异规律及其动力机制....................................................... 47

4.1 引言.............................................................................................................................. 47

4.2 OFAM3模式输出数据评估...................................................................................... 48

4.3 涡动能的季节变异规律............................................................................................. 50

4.3.1 涡动能的季节变化特征......................................................................................... 50

4.3.2 涡动能的能量来源.................................................................................................. 51

4.3.3 涡动能的再分布和耗散......................................................................................... 55

4.4 典型涡旋生成事件..................................................................................................... 58

4.4.1 地形影响下局地风场变化诱发的涡旋生成事件................................................ 59

4.4.2 岛屿尾涡.................................................................................................................. 62

4.5 讨论.............................................................................................................................. 63

4.6 本章小结...................................................................................................................... 64

5 苏拉威西海涡动能年际变异规律及其驱动机制.............................................. 67

5.1 引言.............................................................................................................................. 67

5.2 OFAM3模式输出数据评估...................................................................................... 68

5.3 年际变化特征............................................................................................................. 70

5.4 驱动机制...................................................................................................................... 73

5.4.1 背景流正压不稳定与棉兰老流入侵过程的调控作用....................................... 73

5.4.2 赤道太平洋西边界流与中尺度涡的影响............................................................ 78

5.5 讨论.............................................................................................................................. 80

5.6 本章小结...................................................................................................................... 83

6 总结与展望............................................................................................................. 85

6.1 主要结论...................................................................................................................... 85

6.2 创新点.......................................................................................................................... 86

6.3 未来工作展望............................................................................................................. 86

参考文献............................................................................................................................. 89

附录  评估BRAN再分析资料对印尼海中尺度涡的刻画能力................................. 111

致谢................................................................................................................................... 119

作者简历及攻读学位期间发表的学术论文与其他相关学术成果........................... 121

Document Type学位论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/185205
Collection海洋环流与波动重点实验室
中国科学院海洋研究所
Recommended Citation
GB/T 7714
郝占久. 印度尼西亚海域中尺度涡的时空分布特征与机制研究[D]. 中国科学院海洋研究所. 中国科学院大学,2024.
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