Deep-Water Sea-Floor Array Observations of Seismo-Acoustic Noise in the EasternPacific and Comparisons with Wind and Swell

摘要

We report results from the analysis of data from an array of Ocean-BottomSeismographs (OBSs) employed in an array of 150 meter aperture at a depth of 3800 meters off the California coast. The array recorded noise samples four times per day for a month using pressure and three-component inertial sensors. Comparison of the month-long noise spectrograms with swell spectrograms and wind hindcasts shows marked similarities. In the 0.05-1.0 Hz range the frequency-doubling of swell energy into sea-floor noise predicted by the wave interaction theory is evident. In the 1-10 Hz range the wind-related effects dominate. Lulls in the wind produce deep notches in the noise level. During times of high wind, saturation of the wind wave spectrum causes limiting and reduces the size of the noise maxima. The wind estimates are from the meteorological model of the U.S. Navy Fleet Numerical Oceanography Center and the swell estimates are from their Global Spectral Ocean Wave Model.... Seismo-acoustic noise, Spatial coherence, Ocean-bottom seismometers.