Slowdown of the topography trapped wave propagation by the Dongsha Islands in the northern South China Sea

Based on the satellite altimeter data, it is found that the topography trapped wave (TTW) propagates along the continental shelf in the northern South China Sea (NSCS). The TTW obviously slows down while passing by the Dongsha Islands. Using a quasi-geostrophic equation including the topography effect, we found that the topographic gradient induced by the Dongsha Islands determines the propagation speed, leading to the slowdown of the TTW.