WP 2

Process modelling of physical eddy dynamics

 

Work Package Leaders

Description

Lateral transports and mixing processes by ocean eddies and vertical mixing by internal gravity waves are horizontally and vertically very inhomogeneous such that in particular in coastal upwelling regions weakly ventilated regions are located close to strongly mixed regions and thus effect the wind driven upwelling process and biogeochemical processes of the system.

This project will investigate the effect of the interaction between high-frequency internal gravity waves, the low frequency geostrophically balanced eddies and the mean wind-driven circulation on the lateral and vertical transports in the coastal upwelling region, in particular the role of sub-meso-scale vs. meso-scale eddy variability (see figure 1). A combination of numerical ocean modelling, ray tracing of internal gravity waves and comparison with high-resolution observations made in this collaborative project will be used.

 

General Questions and Research topics

  • To numerically simulate the advective, diffusive, lateral and vertical tracer transports by meso- to submesoscale dynamical structures
  • To validate the simulated transports by the biogeochemical and large-scale physical observations made in this collaborative project
  • To investigate the energy exchange between internal gravity waves with the geostrophically balanced flow by comparison with high resolution Glider and microstucture measurements made in this collaborative project
  • To quantify the generation of small-scale turbulence density and tracer mixing by the dissipation of internal gravity waves and the geostrophically balanced flow.

By this work we will better understand the importance of lateral and vertical mixing and the induced transports on the biogeochemical system of the coastal upwelling system to better forecast changes in the system.

 

Figure 1. The difference between meso- and submesoscale regimes: Kinetic energy in an idealized model simulation of shear instability. Left panel for large Rossby number (or small Richardson number Ri) or so-called submesoscale regime, and right panel for small Rossby number (or large Richardson number Ri) or meso-scale regime."

Figure from Chouksey, M., Eden, C. and Brüggemann, N. (2018): Internal gravity wave emission in different dynamical regimes. J. Phys. Ocean., 48 (8), 1709–1730

 

 

Carsten Eden