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南极海冰变化及其地脉动响应
林建民
同济大学
摘要:
南极海冰的时空分布及变化对地脉动的激发与信号特征具有显著影响,为通过地震学方法研究海冰提供了可能。本文在简要回顾近五十年以来对南极海冰的遥感观测研究基础上,针对近年来新兴的极地地震学重要分支?—基于地震背景噪声的海冰研究,系统阐述了地脉动激发机理和源区分布,并对南极地脉动信号的时空特征及其与南极海冰变化之间的关系进行了综合分析。另外,本文通过BEAR地震台2011-2018年间连续记录数据及相应海冰遥感数据的联合分析,发现:(1)西南极沿岸地区地脉动信号具有明显的季节性变化特征,即SFM能量每年4-5月左右最强,10-11月附近最弱;而DFM最强能量则对应每年2-3月左右,10月左右最弱。其中DFM能量变化与海冰具有更好的一致性。(2)因为地脉动的能量还受源位置、强度(风暴潮、波浪场等因素)的影响,所以,地脉动能量变化与海冰变化的时间并未严格对应。最后,本文还讨论了南半球环状模对南极海冰及地脉动的影响,并对通过地震学方法研究海冰变化与气候变化当前存在的问题以及未来发展前景进行了分析与展望。
关键词:  南极海冰  地脉动  气候变化  南环状模
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Microseism variations in response to Antarctic sea ice change
Lin Jianmin
Tongji University
Abstract:
The temporal and spatial distributions of Antarctic sea ice play an important role in both the generation mechanisms and signal characteristics of microseisms. This link has paved the way for seismological investigations of Antarctic sea ice. Here we present an overview of the current state of seismological research about microseisms on Antarctic sea ice. We first briefly review satellite remote–sensing observations of Antarctic sea ice over the past 50 years. We then systematically expound upon the generation mechanisms and source distribution of microseisms in relation to seismic noise investigations of sea ice, and the characteristics of Antarctic microseisms and their relationship with sea ice variations are further analyzed. We also analyze the continuous waveform data that were recorded at seismic station BEAR in West Antarctica from 2011 to 2018 and compare the microseism observations to the corresponding satellite remote–sensing observations of Antarctic sea ice. Our results show that: (1) microseisms from the coastal regions of West Antarctica exhibit obvious seasonal variations, SFM with maximum intensities every April–May and minimum intensities around every October–November; while DFM intensities peak every February–March, and reach the minimum around every October. Comparatively, the strong seasonal periodicity of Antarctic sea ice in better agreement with the observed DFM; and (2) microseism decay is not synchronous with sea ice expansion since the microseism intensity is also linked to the source location and source intensity (e.g., ocean storms, ocean wave field), and other factors. Finally, we discuss the effect of Southern Annular Mode on Antarctic sea ice and microseisms, as well as the current limitations and potential of employing seismological investigations to elucidate Antarctic sea ice variations and climate change.
Key words:  Antarctic sea ice  Microseisms  Climate change  the Southern Annular Mode