| 利用EEMD及超导重力数据探测超低频地球自由振荡模态分裂信号：探测实例 |
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| 引用本文： | 江颖,刘子维,张苗苗,郝洪涛,李辉.利用EEMD及超导重力数据探测超低频地球自由振荡模态分裂信号：探测实例[J].大地测量与地球动力学,2016,36(8):689-702. |
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| 作者姓名： | 江颖 刘子维 张苗苗 郝洪涛 李辉 |
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| 摘 要： | 利用2004年苏门答腊9.0级地震后GGP台网中15台超导重力仪的18组观测数据，采用EEMD分解技术及叠积技术，检测了频率小于1 mHz的低频地球自由振荡的简正模（3S1、0S4、0S5）及其频谱分裂现象。通过对原始分钟间隔的超导重力数据进行预处理得到重力残差，然后运用EEMD方法将其分解到处于不同频段上的IMF分量，提高了探测低频自由振荡信号的信噪比，使一些低频自由振荡信号的谱线分裂更清晰地显现出来。结果表明，经过EEMD分解过的重力残差能更有效地检测低频自由振荡信号，得到信噪比更高的低阶球型振荡分裂谱线。该研究进一步证实了EEMD数据处理方法的有效性以及超导重力仪在低阶地球自由振荡检测中的优越性。
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| 关 键 词： | 地球背景噪声 低频地球自由振荡 频率 振幅 品质因子 |
Research on Background Noise Level of Global Superconducting Gravimeter |
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| JIANG Ying,LIU Ziwei,ZHANG Miaomiao,HAO Hongtao,LI Hui.Research on Background Noise Level of Global Superconducting Gravimeter[J].Journal of Geodesy and Geodynamics,2016,36(8):689-702. |
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| Authors: | JIANG Ying LIU Ziwei ZHANG Miaomiao HAO Hongtao LI Hui |
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| Abstract: | The background noise level in seismic frequency band (200-600 s) based on four years continuous observation of superconducting gravimeter (SG) at Lhasa station is investigated, and the influence of power spectral density (PSD) caused by atmosphere and sampling rate is also studied. The noise level of SG observation provided by global geodynamic project (GGP) for 2013 in seismic frequency band and sub-seismic frequency band are calculated, and they are further analyzed and compared. It is found that the PSD of gravity can be improved by tides and atmosphere correction when the frequency is below 10-3 Hz. When the frequency is below 0.5×10-3 Hz, the noise level of SG is obviously better than that of a seismometer. This means that SG is more suitable for researching long-period seismic and sub-seismic modes.The range of the seismic noise magnitude of global SG is 0.180-1.964, and the range of sub-seismic noise magnitude is 1.860-3.853. |
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| Keywords: | superconducting gravimeter noise level NLNM power spectral density |
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