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Deciphering Climate Information From Array Ambient Noise in Groningen

Description: 

Ocean waves, storing the information of climate change and celestial body movement, contribute significantly to seismic ambient noise. We collected seven-year continuous array seismic data in the Groningen area from 2016 to 2022 to investigate the spatiotemporal variations of offshore ambient noise. The spatial features of ocean waves were tracked through beamforming of seismic ambient noise. The lower-frequency sources, below 1.0 Hz, were tracked from the direction of the North Sea, and the higher-frequency sources were tracked from the direction of bocht van watum, which is a marine channel in Groningen. The frequency dispersion curves were extracted by the frequency-wavenumber analysis. To study the temporal features of seismic ambient noise, we conducted long-term time dependent frequency analysis, that revealed seasonal and annual variations of noise generated by the ocean over the last seven years. The time dependent spectra amplitude showed an obvious period of 29-30 days which related to the moon phase cycle. More interestingly, the relationship between seismic noise and North Atlantic Oscillation (NAO) was revealed. The seismic noise generated by the single frequency wave (SFW) in the band 0.16-0.20Hz and double frequency wave (DFW) in the band 0.30-0.36Hz have a positive correlation with NAO, whose trend is consistent with NAO. However, the seismic noise around 0.07Hz has a negative correlation and the oscillation phase reverse to that of NAO. These analyses show the potential of using existing off-shore seismic monitoring systems for studying global climate change and physical oceanography.

Session: Monitoring Climate Change With Seismology

Type: Oral

Date: 4/18/2023

Presentation Time: 10:30 AM (local time)

Presenting Author: Yichen Zhong

Student Presenter: Yes

Invited Presentation: 

Authors