Observations of infragravity waves at the ocean-bottom broadband station

Speaker : Tzu-Chuan Lee

Abstract
We report observations of infragravity waves in the period band 30–400 s at two broadband ocean-bottom seismic stations, KEBB and MOBB. When compared to the energy of the short-period ocean waves recorded at the local buoys, infragravity waves in the longer than 20 s period band are found to be mainly locally generated from shorter-period waves. Two types of modulation of the infragravity signal are observed. First, the entire infragravity band signal is modulated in-phase with tides, possibly as a result of the nonlinear exchange of energy between the short-period waves and tidal currents. Second, a longer-period modulation of the infragravity signal is observed and is best correlated with the energy of the 14 s period ocean waves. This correlation indicates that the mechanism of generation of double frequency microseisms and infragravity waves are likely strongly related.

References

• Dolenc, D., B. Romanowicz, P. McGill and W. Wilcock (2008), Observations of infragravity waves at the ocean-bottom broadband seismic stations Endeavour (KEBB) and Explorer (KXBB), Geochem. Geophys. Geosyst., 9, Q05007, doi:10.1029/2008GC001942.
• Dolenc, D., B. Romanowicz, D. Stakes, P. McGill, and D. Neuhauser (2005), Observations of infragravity waves at the Monterey ocean bottom broadband station (MOBB), Geochem. Geophys. Geosyst., 6, Q09002, doi:10.1029/2005GC000988.