Oceanic swells generated by storms can sometimes propagate over long distances across the oceans. In this study, we propose a new method to retrace the sources and routes of swells generated in the Southern Ocean using the Surface Waves Investigation and Monitoring (SWIM) instrument onboard the Chinese-French Oceanography Satellite (CFOSAT), ERA5 reanalysis data, and buoy data from the National Data Buoy Center (NDBC). We found 25 routes for swells that were generated by 4 ocean storms in the Southern Ocean from May to August 2019. The decay rate of the swell energy is found to increase with the spectral width of the initial swell field. The general rate of increase of the peak wavelength is ~0.01 m/km, and is apparently dependent on the spectral width. We used a point source model and the wave model data from a two-month run of WAVEWATCH III (WW3) to calculate the linear dissipation rates of swells propagating at different stages. The linear dissipation rate decreases with increasing distance from the swell source. The point source model yielded dissipation rates of -1.4 to 2.4×10^-7 m^-1. In addition, nonlinear dissipation rates were calculated based on the air–sea interaction theory and wave–turbulence interaction theory.