On Contributions of Multiscale Dynamic Processes to the Steric Height in the Northeastern South China Sea as Revealed by Moored Observations

Based on 2-year moored measurements in the northeastern South China Sea, contributions of multiscale dynamic processes to steric height (SH) at 60 m are quantified. It shows that on average, root-mean-squared (RMS) SHs of mesoscales, submesoscales, diurnal and semidiurnal internal tides (ITs), and supertidal internal gravity waves (IGWs) are 7.56, 1.01, 1.19, 2.84, and 1.46 cm, respectively, with their respective relative contributions of 53.8%, 7.2%, 8.5%, 20.2%, and 10.4%. The SHs of ITs and supertidal IGWs are dominated by stationary and nonstationary components, respectively. Seasonally, mesoscales and submesoscales show larger RMS SHs in winter than summer but the opposite occurs for ITs and supertidal IGWs. Although the RMS SH of submesoscales exceeds nonstationary ITs in winter, it is much smaller than the sum of nonstationary ITs and supertidal IGWs. Therefore, to detect submesoscales using SWOT data, approaches to remove the SHs of nonstationary ITs and supertidal IGWs are called for.