Buoy Observations of Ocean Swell Propagation Across the Pacific Ocean

Abstract A network of more than 300 drifting wave buoys is used to study the propagation of ocean swell across the Pacific Ocean. Swell events are identified at buoys in the Equatorial region and then tracked along Great Circle propagation paths both forward and backward in time. In this way, other buoys are identified at points along the propagation path and the generating storm can be determined by combining the assumed propagation path with spectral model hindcasts. Swell can be tracked over periods up to 12 days and propagation paths of 12,000 km. The analysis compares measured and predicted arrival times of swell between the buoys. The mean propagation times are well predicted by linear theory but with scatter up to hours. This range is consistent with the statistical uncertainty of the buoy spectral measurements. Decay rates of the swell are consistent with previous measurements and well modeled by the WAVEWATCH III spectral wave model. The analysis was conducted as a function of frequency, confirming that higher frequency swell decays more rapidly than lower frequencies.