Internal Subseasonal Variability in the South China Sea Revealed by Eddy‐Resolving Numerical Simulations

Oceanic subseasonal variabilities in the South China Sea (SCS) derive from both external forcing and internal variability. There have been extensive studies on a range of external forcings, which are composed of local and remote components. In this study, the internal subseasonal variabilities in SCS are examined using an eddy‐resolving model. It is found that the internal subseasonal variabilities are pronounced in the northern SCS, which account for about half of total observed subseasonal variabilities. Particularly to the west of Luzon Strait, the internal subseasonal variabilities are enhanced on the periphery of a ring region. On the contrary, internal subseasonal variabilities are minimal in the center, which is mainly attributable to an upscale energy transfer. As a result, a mean jet is generated which transports heat and eddy kinetic energy along the edge of the ring region. We posit that the impact of internal subseasonal variabilities is significant for the background state in the region where the intense tropical cyclones occur over the northern SCS every year.