Analysis of the Differences in Internal Solitary Wave Characteristics Retrieved from Synthetic Aperture Radar Images under Different Background Environments in the Northern South China Sea

Two internal solitary waves (ISWs) with very long fronts observed by synthetic aperture radar (SAR) images in the northern South China Sea (NSCS) are comparatively analyzed based on oceanic reanalysis data and the Korteweg-de Vries (KdV) theory. The differences in the environmental parameters, wave half-width, and amplitude of the two ISW fronts in the two distinct oceanic environments are studied. In the presence of a weak westward surface current of approximately 0.05 m/s, the values of the linear wave speed increase by up to 0.056 m/s, and the retrieved ISW amplitudes decrease by up to 14 m. On the contrary, for another background oceanic environment considering a relatively strong eastward surface current of approximately 0.2 m/s, there are decreases of up to 0.17 m/s in the linear wave speed and increases of up to 32 m in the retrieved amplitudes. However, the results retrieved from both the SAR observations commonly show that the ISW amplitudes along the fronts reach their maximums at roughly 21 & DEG;N and decrease toward the southern and northern sides, in spite of their distinct background environments.

Automated summary

Two internal solitary waves (ISWs) with long fronts in the northern South China Sea (NSCS) were analyzed comparatively based on oceanic reanalysis data and the Korteweg-de Vries (KdV) theory. The study examined the differences in environmental parameters, wave width, and wave amplitude between the two ISW fronts in distinct oceanic environments. The results showed that the presence of a weak westward surface current led to increased linear wave speed and decreased ISW amplitude, while a relatively strong eastward surface current resulted in decreased linear wave speed and increased ISW amplitude. However, it was found that the ISW amplitudes reached their maximums at around 21°N and decreased towards the southern and northern sides regardless of the background environments.