Read Haller & Beron Vera (2013)

[rabernat]

Haller, G., & Beron-Vera, F. (2013). Coherent Lagrangian vortices: The black holes of turbulence. Journal of Fluid Mechanics, 731, R4. doi:10.1017/jfm.2013.391

https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/abs/coherent-lagrangian-vortices-the-black-holes-of-turbulence/3B50A4590B35E5637280F01A58502258

This is a very mathematical paper focusing on Agulhas eddies. It's a difficult read but will give you some idea of the theoretical complexity involved in this topic.