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

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.