(???????)?????????????On the Variation of Dissipation Flux Coefficient in the Upper South China Sea

This study focuses on the statistical features of dissipation flux coefficient gamma in the upper South China Sea (SCS). Based on the microscale measurements collected at 158 stations in the upper SCS and derived dissipation rates of turbulent kinetic energy and temperature variance epsilon and x(T) , via a modified method, we estimate gamma and analyze its spatiotemporal variation in an energetic and a quiescent region. We show that gamma is highly variable, which scatters over three orders of magnitude from 10(-21) to 10(1) in both regions. In the energetic region, gamma is slightly greater than in the quiescent region; their median values are 0.23 and 0.17, respectively. Vertically, gamma presents a clear increasing tendency with depth in both regions, though the increasing rate is greater in the energetic region than in the quiescent region. In the upper SCS, gamma positively depends on the buoyancy Reynolds number Reb and negatively depends on the ratio of the Ozmidov scale to the Thorpe scale R-OT and is scaled as gamma alpha Re-b(1/2) R-OT(-4/3) , which holds for both regions. The vertical decreasing of R-OT is observed, which yields parameterization of R-OT = 10(-0.002z) this parameterization improves the performance of the Thorpe scale method by reducing at least 50% of the bias between the observed and parameterized epsilon. These results shed new light on the spatiotemporal variability and modulating mechanism of gamma in the upper ocean.