| 台风激发的第二类地脉动特征及激发模式分析 |
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| 引用本文： | 郑露露,林建民,倪四道,祝捍皓,郑红.台风激发的第二类地脉动特征及激发模式分析[J].地球物理学报,2017,60(1):187-197. |
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| 作者姓名： | 郑露露 林建民 倪四道 祝捍皓 郑红 |
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| 作者单位： | 1. 浙江海洋大学海洋科学与技术学院, 浙江舟山 316022;2. 中国科学院测量与地球物理研究所大地测量与地球动力学国家重点实验室, 武汉 430077 |
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| 基金项目： | 国家自然科学基金（41104027），浙江省自然科学基金重点项目（LZ14D060001），大地测量与地球动力学国家重点实验室开放基金（SKLGED2013-1-7-E），海洋科学浙江省重中之重学科开放课题（20130113），浙江海洋大学科研启动项目（21105011813）和中国科学院重要方向性项目（KZCX2-EW-121）共同资助. |
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| 摘 要： | 0.003~1 Hz频段的地脉动主要来源于海浪运动与固体地球的耦合作用,台风引起的强烈海浪运动往往可使地脉动能量显著增强.由于涉及大气-海洋-固体地球三个圈层之间的复杂动量传递与耦合过程,迄今为止,关于台风激发地脉动的具体源区位置及激发机制尚存在争议.本文选取日本、中国东南沿海及台湾地区的地震台站波形连续记录,研究了2008年台风"森拉克"和"黑格比"激发地脉动的时频特征,开展相应数值模拟,并与观测数据进行了对比分析研究.结果表明台风激发第二类地脉动存在两种主要模式:(1)近岸源区激发,即台风引起波浪入射至海岸反射并与后续来波相互作用形成驻波作用于海底而激发;(2)台风中心附近源区激发,即台风中心移动过程中不同时期激发的同频率波浪相向传播、相互作用产生驻波作用于海底而激发,源区位置主要集中于台风中心左后方.此外,结合波浪再分析数据、台风风场特征,我们进一步对第二类地脉动激发过程中的影响因素进行了分析,发现:第一种模式激发的地脉动与近岸源区波浪场强度、观测点至源区距离及台风中心至海岸线距离等因素相关;而第二种模式激发的地脉动则主要受台风中心附近波浪场的频率成分与传播方向影响.
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| 关 键 词： | 台风 海浪 地脉动 时频特性 数值模拟 激发模式 |
| 收稿时间： | 2016-02-15 |
Characteristics and generation mechanisms of double frequency microseisms generated by typhoons |
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| ZHENG Lu-Lu,LIN Jian-Min,NI Si-Dao,ZHU Han-Hao,ZHENG Hong.Characteristics and generation mechanisms of double frequency microseisms generated by typhoons[J].Chinese Journal of Geophysics,2017,60(1):187-197. |
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| Authors: | ZHENG Lu-Lu LIN Jian-Min NI Si-Dao ZHU Han-Hao ZHENG Hong |
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| Institution: | 1. School of Marine Science and Technology, Zhejiang Ocean University, Zhoushan Zhejiang 316022, China;2. State Key Laboratory of Geodesy and Earth's Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China |
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| Abstract: | Microseisms in the band of 0.003~1 Hz are mainly generated by the coupling between ocean waves and the solid Earth. Typhoons generate large ocean waves on the sea surface and the energy can be effectively transferred into seismic waves and recorded as microseisms. As the complexity of the energy transmission and coupling process among Atmosphere-Ocean-Solid Earth, the generation mechanisms and source locations of microseisms generated by typhoons and ocean waves are still under debate. We analyze the microseisms generated by Typhoon Sinlaku and Typhoon Hagupit in 2008 with continuous seismic wave record in Japan, southeastern China and Taiwan as well as via numerical modeling. We identify two types of source regions of double frequency (DF) microseisms:(1) Coastal excitation region, where ocean waves generated by typhoons propagate towards coastlines and interfere with following incident ocean waves after reflection to form standing waves, and induce pressure fluctuations on the seafloor to generate DF microseisms. (2) Excitation region near typhoon center. Standing waves can be formed in the left-rear quadrant of the typhoon center during its moving, by interaction of two wave trains with same frequency but opposite propagation directions, which were generated at different times. In addition, we investigate the potential influence factors for the generation of DF microseisms by utilizing re-analysis ocean wave data and analyzing the characteristics of wind fields of extreme typhoons. We find that the microseisms generated by coastal source regions match well with the intensity of ocean wave at source regions, the distance from seismic station to coastal source regions and the distance from typhoon center to coastlines, while the microseisms generated at the source region near typhoon center are mainly controlled by the directional spectrum of the ocean wave field around typhoon center. |
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| Keywords: | Typhoon Ocean wave Microseisms Temporal-frequency characteristics Numerical modeling Generation mechanisms |
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