Microstructure measurements and finescale parameterization assessment of turbulent mixing in the northern South China Sea

Both microscale and finescale measurements were conducted along 20 degrees N and 21 degrees N in the northern South China Sea (SCS) during July 2007. Spatial variability of turbulent kinetic energy (TKE) dissipation rate was examined, and two finescale parameterizations were assessed and compared. TKE dissipation rates along the 21 degrees N section were found to be much higher than those along 20 degrees N; in particular, remarkably high TKE dissipation rates existed near the Luzon Strait and around the Dongsha Plateau, which were likely caused by internal tides and internal solitary waves, respectively. The Gregg-Henyey scaling does not work well in the northern SCS, while the MacKinnon-Gregg scaling with a modified parameter matches the observations in both magnitude and variability. One explanation is that the large-scale/low-mode shear mainly comes from low-frequency internal waves such as internal tides, which are not described well by the Garrett-Munk spectrum.