Comparisons on One-dimensional Ocean Wave Spectrum Models Based on SWIM/CFOSAT Observations

The ocean wave spectrum models not only characterize the rough sea surface but also reveal the internal energy distribution of waves with wave numbers and directions, providing information for air-sea interaction research and ocean exploration applications. The Surface Waves Investigation and Monitoring instrument (SWIM) onboard the China France Oceanography Satellite (CFOSAT) can obtain spatial observations of global ocean wave directional spectra. In this research, the status of existing wave spectrum models and observations were summarized, then the statistical characteristics of wave parameters observed by SWIM are analyzed. To investigate the specific performance of the Apel spectrum, Elfouhaily spectrum, and Goda spectrum model in different sea states, the sea states are labelled in different categories according to the well-applied wave field characterization features. Then the measured ocean wave spectra within the range of wave numbers (0.01～0.25 rad·m^–1) under different sea states were compared with the height and curvature spectra in the spectrum models under different sea states. The differences between the existing wave observations and the above three spectra are quantified and combined in their statistical characteristics in terms of the ocean wave parameters. The results indicate that when the inverse wave age is less than 0.8, the Goda wave height spectrum and Elfouhaily curvature spectrum are the closest in terms of the wave height spectrum and curvature spectrum to SWIM observations respectively. When the inverse wave age is between 0.8 and 0.9, the Apel wave height spectrum and curvature spectrum are most closely aligned with the measured data from SWIM. When the inverse wave age is between 0.9 and 1.0, the Goda wave height spectrum and Apel curvature spectrum are most closely matched with the wave height spectrum and curvature spectrum from the SWIM product respectively. Conclusions are drawn that the reasons for the differences between SWIM observations and existing models mentioned above are due to their conditional assumptions and incomplete expression of the sea states, while in the natural sea environment, these assumptions hold but for quite a limited fraction. The result supports the follow-up research of wave spectrum model and observation applications.