Received: 29 Mar 2018 – Discussion started: 07 May 2018
Abstract. Tilting mesoscale eddies in the South China Sea have been reported recently from observed field data. The mechanism of the dynamic process of the tilt, however, is not well understood. In this study, the influence of planetary β on the vertical structure of mesoscale eddies and its mechanism is investigated using theoretical analysis and numerical model experiments based on the MIT General Circulation Model (MITgcm). The results of the both approaches show that vertical motion due to the planetary β effect and nonlinear dynamics causes a pressure anomaly in the horizontal domain which triggers the tilt of the eddy axis. The tilting distance extends to be the radius of the eddy maximum velocity. In addition, the vertical stratification is another key factor in controlling the tilt of a mesoscale eddy. External forcings such as wind and inflow current are not considered in this study, and topography is included only in a realistic South China Sea model. Therefore, mesoscale eddies with large vertical depth should have the similar axis tilt character in open oceans under the β-effect.
How to cite. Yang, S., Xing, J., Chen, S., Tian, J., and Chen, D.: The impact of the planetary β-effect on the tilting vertical structure of
a mesoscale eddy, Ocean Sci. Discuss. [preprint], https://doi.org/10.5194/os-2018-39, 2018.
Motivated by the recent field observations of the eddy tilting structure in the South China Sea, a simple theoretical analysis and a numerical model (MITgcm) are used to investigate the mechanism of the vertical structure tilt of a mesoscale eddy on the β-plane. The model results correspond well with the theoretical analysis and the results indicate that the β-effect, nonlinear advection, and ocean stratification are important factors in controlling the vertical structure of a mesoscale eddy.
Motivated by the recent field observations of the eddy tilting structure in the South China Sea,...