Impact of Model Resolution on Mixing and Dispersion in the Gulf of Mexico

We investigate the importance of model resolution in identifying the nature of mixing and dispersion in the Gulf of Mexico, by comparing two data-assimilative, high-resolution simulations, one of which is submesoscale-resolving. By employing both Eulerian and Lagrangian metrics, upper-ocean differences between the mesoscale- and submesoscale-resolving simulations are examined. Focusing on regions characterized by high submesoscale activity, we approach the notion of mixing by tracking the generation of Lagrangian Coherent Structures (LCSs) and transport barriers. Finite-time Lyapunov exponents (FTLE) fields reveal higher separation rates of fluid particles in the submesoscale-resolving case which indicates more vigorous mixing. Using probability density functions (PDFs), the extent of mixing homogeneity is also explored, with preliminary results suggesting that mixing is more homogeneous in the submesosclae-resolving case. Finally, we aim to identify regions of convergence in the areas of interest by advecting passive tracers that tend to organize themselves along attracting LCSs. Applications of passive tracer advection are then translated to extreme event situations, such as the Deepwater Horizon.