5:15 PM - 6:45 PM
[SSS03-P06] Infragravity wave generation and propagation in the Pacific Ocean revealed by ambient noise correlation
Keywords:infragravity waves, Pacific Ocean, ocean bottom pressure data, cross-correlation function, Earth's Hum
In this study we analyzed ocean bottom pressure data to constrain infragravity wave generation and propagation. Infragravity waves, generated when an ocean storm hits the continental shelf and the coast landward, are low-frequency ocean waves with an apparent velocity of only a few hundred meters per second. These waves alter wave height as they propagate through the ocean and have been considered the source of Earth’s Hum. However, the detailed mechanism has not yet been fully resolved due to the lack of direct, continuous observations of infragravity waves. Our goal is to better understand infragravity wave behaviors, including constraining their source and spatiotemporal variation.
We collected continuous data of differential pressure gauges from multiple OBS arrays deployed at the Pacific seafloor over the past 20 years. Compared to seismic data, the choice of pressure data avoids waveform contaminations caused by the arrival of seismic waves and subsequent long-duration coda waves. The collected continuous pressure data were used to calculate cross-correlation functions (CCFs) for each of the available station-pairs. The derived CCFs exhibit clear dispersion of infragravity waves that propagate between two stations. The arrival and amplitude of infragravity waves on CCFs in causal and acausal parts imply discrepancies in distribution and intensity of the source on both sides. The continuous daily CCFs provide an opportunity to constrain the temporal variation of infragravity wave behaviors on a seasonal or even annual basis. By integrating results from multiple OBS arrays, we are able to precisely locate the source of infragravity waves and may have a better understanding of the origin and generation mechanism of infragravity waves to advance our insights into the physical phenomena of hum generation, which may have potential applications in exploring the Earth's deep structure.
We collected continuous data of differential pressure gauges from multiple OBS arrays deployed at the Pacific seafloor over the past 20 years. Compared to seismic data, the choice of pressure data avoids waveform contaminations caused by the arrival of seismic waves and subsequent long-duration coda waves. The collected continuous pressure data were used to calculate cross-correlation functions (CCFs) for each of the available station-pairs. The derived CCFs exhibit clear dispersion of infragravity waves that propagate between two stations. The arrival and amplitude of infragravity waves on CCFs in causal and acausal parts imply discrepancies in distribution and intensity of the source on both sides. The continuous daily CCFs provide an opportunity to constrain the temporal variation of infragravity wave behaviors on a seasonal or even annual basis. By integrating results from multiple OBS arrays, we are able to precisely locate the source of infragravity waves and may have a better understanding of the origin and generation mechanism of infragravity waves to advance our insights into the physical phenomena of hum generation, which may have potential applications in exploring the Earth's deep structure.