The TKE dissipation rate in the northern South China Sea

The microstructure measurements taken during the summer seasons of 2009 and 2010 in the northern South China Sea (between 18A degrees N and 22.5A degrees N, and from the Luzon Strait to the eastern shelf of China) were used to estimate the averaged dissipation rate in the upper pycnocline aOE (c)epsilon (p)> of the deep basin and on the shelf. Linear correlation between aOE (c)epsilon (p)> and the estimates of available potential energy of internal waves, which was found for this data set, indicates an impact of energetic internal waves on spatial structure and temporal variability of aOE (c)epsilon (p)>. On the shelf stations, the bottom boundary layer depth-integrated dissipation reaches 17-19 mW/m(2), dominating the dissipation in the water column below the surface layer. In the pycnocline, the integrated dissipation was mostly similar to 10-30 % of . A weak dependence of bin-averaged dissipation on the Richardson number was noted, according to , where epsilon (0) + epsilon (m) is the background value of for weak stratification and Ri (cr) = 0.25, pointing to the combined effects of shear instability of small-scale motions and the influence of larger-scale low frequency internal waves. The latter broadly agrees with the MacKinnon-Gregg scaling for internal-wave-induced turbulence dissipation.