基于OBS数据的阿拉伯海盆背景噪声分析

Analysis of Ambient Noise in the Arabian Basin Based on OBS Data

  • 摘要: 除天然地震信号外,在海底连续观测的海底地震仪(Ocean-Bottom Seismograph, OBS)还记录了丰富的海底环境背景噪声数据。这些数据对于揭示区域性的海底环境噪声以及海洋活动特征等有着重要意义。本研究基于布设在阿拉伯海盆中部的被动源OBS观测台阵数据,采用功率谱密度概率密度函数方法,在全频段上对阿拉伯海区域的背景噪声特征进行了定量分析,以评估数据质量。结果表明,阿拉伯海的背景噪声特征与南海、楚科奇海等边缘海相近,仅在1~5 s的双频微地动(Double Frequency Microseisms, DFM)频段有一个单峰值,这表明其DFM能量主要来自阿拉伯海本地。为了对DFM的产生进行溯源,进一步分析DFM频段的季节性变化特征发现,夏、冬两季爆发的印度季风会对噪声水平产生重大影响,两季噪声水平均高于季风强度较弱的春季。此外,利用皮尔逊相关方法探究海洋波高与功率谱密度的关系发现,印度洋热带气旋爆发除引起海洋波高增大外,其皮尔逊相关系数曲线也会出现峰值,证实了极端海况对噪声水平的控制作用。本研究结果对于理解阿拉伯海区的季节性海洋活动特征、处理该台阵数据及开展后续地震学研究具有重要意义。

     

    Abstract: In addition to seismic signals, ocean bottom seismometers (OBS) continuously deployed on the seafloor also record abundant ambient noise data of the marine environment. These data are of great significance for revealing regional marine ambient noise and marine activity characteristics. This study is based on the data from a passive source ocean bottom seismometer (OBS) array deployed in the central Arabian Sea Basin to investigate the characteristics of ambient noise in this area, in order to assess the data quality of the OBS and facilitate the exploration of relevant noise reduction methods for subsequent applications. We utilized the probability density function method of power spectral density to quantitatively analyze the ambient noise characteristics of the Arabian Sea region across the full frequency band. It was found that the ambient noise characteristics of the Arabian Sea are similar to those of marginal seas such as the South China Sea and the Chukchi Sea, with only a single peak in the 1s-5s double-frequency microseism (DFM) frequency band, indicating that the main energy of the DFM in the Arabian Sea comes from the local area. To trace the source of the DFM signal, we analyzed the seasonal variation characteristics of the DFM frequency band and found that the Indian monsoon, which occurs in summer and winter, has a significant impact on the noise level. The overall noise levels in both seasons are higher than those in spring when the monsoon intensity is lower. Additionally, we used the Pearson correlation method to explore the relationship between ocean wave height and power spectral density and found that during the outbreak of tropical cyclones in the Indian Ocean, not only does the ocean wave height increase, but the Pearson correlation coefficient curves also show a peak, verifying the control effect of extreme sea conditions on the background noise level of the Arabian Sea. These findings are of great benefit for understanding the seasonal marine activity characteristics of this Arabian Sea area and for data processing and subsequent seismological applications of this array.

     

/

返回文章
返回