Estimate of Mixing Driven by Internal Waves Propagating Through a Geostrophic Front

Qiang Li, Xian-Zhong Mao and Peng Yin, Tsinghua University, Graduate School at Shenzhen, Beijing, China
Abstract:
In the deep ocean, internal waves can propagate in a long distance. It is assumed in the traditional internal wave theory that background stratification is horizontally uniformed. Apparently, this is not true in the real ocean due to existence of global circulation, eddies, etc. Here, we investigate the internal wave generation and propagation as the background stratification is dominated by a geostrophic front, such as the Kuroshio, through solving a Sawyer-Eliassen type equation. Tilted thermocline maintained by geostrophic balance changes fundamental properties of internal waves as well as their interaction with bottom topography. Solutions of the Sawyer-Eliassen equation are compared with the high-resolution numerical results. High mode internal waves will be generated, and the arrested ones are assumed to contribute to local mixing. The mixing rate is then estimated and compared with the model simulation using the appropriate parameterization scheme.