2026/05/19 by Wei Dai, Jian Sun, Xiaoyu Sun +5
Earth and Planetary Sciences · #Ocean Waves and Remote Sensing #Oceanographic and Atmospheric Processes #Meteorological Phenomena and Simulations
paper · doi:10.1175/jpo-d-25-0148.1
Abstract The physical mechanisms governing ocean swell propagation are long-standing issues in physical oceanography. One key aspect is the dissipation of swell energy across the oceans, which is constrained due to limitations in observational coverage. In this study, the trans-Pacific propagation and dissipation of swells generated by Southern Ocean storms are investigated. Data are sourced from the Chinese–French Oceanography Satellite ( CFOSAT ) Surface Waves Investigation and Monitoring (SWIM) instrument, buoy observations, wave hindcast, and reanalysis. A total of 1755 swell trajectories are traced to quantify spectral evolution, wavelength variation, and energy dissipation along great-circle paths. As swells propagate across the ocean, the spectral width and its distribution range narrow monotonically. This demonstrates the progressive separation of frequency components in space and time as a result of frequency dispersion, leading to a more monochromatic wave field locally. The mean dissipation rate is estimated at 2.09 ± 0.024 × 10 −7 m −1 , with an attenuation rate of 5.05 ± 0.027 × 10 −7 m −1 . This dissipation level is approximately twice that of previous studies and exhibits a systematic bias relative to the trackwise estimate (1.35 × 10 −7 m −1 ), likely reflecting the sensitivity of pointwise calculations to observational noise. Beyond 4000 km from the storm source, both spectral width and its variability narrow significantly. Additionally, the spectrally weighted peak wavelength within the swell partition increases by approximately 11 m (1000 km) −1 of propagation. Significance Statement Southern Ocean swells, which are long ocean surface waves generated by storms, can travel thousands of kilometers across the ocean and impact distant coastal regions due to their relatively low dissipation of energy. Using data from the Chinese–French Oceanography Satellite ( CFOSAT ) Surface Waves Investigation and Monitoring (SWIM) instrument, we tracked how these waves evolve over time and distance. It is found that as swells propagate away from the storm source, their energy decreases, and the energy becomes more monochromatic locally due to the separation of dispersion, as indicated by the narrower widths of the wave spectra. The dissipation rate is statistically quantified across a large number of swell trajectories, revealing systematic variations with distance, wave steepness, and significant wave height.