Observations of infragravity waves at the Monterey ocean bottom broadband station (MOBB)

Abstract

[1] Infragravity waves can be observed at the 1000 m deep ocean bottom broadband seismic station MOBB on stormy as well as quiet days. 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. Previously recorded data during the Oregon ULF/VLF experiment at 600 m water depth also indicate that infragravity waves are primarily locally generated.

Ambient Noise and Teleseismic Signals Recorded by Ocean-Bottom Seismometers Offshore Eastern Taiwan

“…2 are not representative of the long term condition of the seafloor. Nonetheless, as in other reports (e.g., Collins et al 2001;Dolenc et al 2005), the quiet-day snapshot is provided to show end-member scenarios that can be compared with the reference data on land. A sensor that rests on the surface of the sediment is not well coupled to the ground and is subject to tilt by bottom currents which increase the low-frequency noise levels on the horizontal components much more significantly than on the vertical component (e.g., Collins et al 2001).…”

Source characteristics of ocean infragravity waves in the Philippine Sea: analysis of 3-year continuous network records of seafloor motion and pressure

“…IG waves also are considered to excite the Earth's hum Romanowicz 2004, 2006;Tanimoto 2005;Nishida et al 2008;Fukao et al 2010;Nishida 2013). Dolenc et al (2005) compared the power spectra of ocean-bottom seismic records at a station located offshore of the Monterey Bay in California with the wave spectral densities measured by the nearby National Oceanic and Atmospheric Administration (NOAA) buoy. They observed two types of IG wave modulations with short (30-to 40-s) and long (10-day) periods, the latter being correlated with the ocean tides at the station.…”

Refraction and reflection of infragravity waves near submarine canyons

“…Subsequent investigations have shown that infragravity waves are important to sediment transport near the shoreline [Holman and Bowen, 1982;Bauer and Greenwood, 1990], currents in the surfzone [Sasaki et al, 1976;Kobayashi and Karjadi, 1996], oscillations in harbors [Okihiro et al, 1993], and fluctuations in seismic records observed on the continental shelf [Dolenc et al, 2005;Webb, 2007].…”