Medium case benchmark: Double-gyre NEMO configuration

The medium case benchmark is based on an idealized configuration of the NEMO ocean model: a square and 5000-meter deep flat bottom ocean at mid latitudes (the so called square-box or SQB configuration).

In this square basin (between 25°N and 45°N), a double gyre circulation is created by a constant zonal wind forcing blowing westward in the northern and southern parts of the basin and eastward in the middle part of the basin (with sinusoidal latitude dependence). The western intensification of these two gyres produces western boundary currents that feed an eastward jet in the middle of the square basin (see animation below, showing the model sea surface height). This jet is unstable so that the flow is dominated by chaotic mesoscale dynamics, with largest eddies that are about 100 km wide, and to which correspond velocities of about 1 m/s and dynamic height differences of about 1 meter. All this is very similar in shape and magnitude to what is observed in the Gulf Stream (North Atlantic) or in the Kuroshio (North Pacific).

The time evolution of this chaotic system is computed using the NEMO primitive equation model, with a minimum horizontal resolution of 1/4°×1/4° cos(latitude) and 11 levels in the vertical (see Cosme et al. 2010, for more detail about the model configuration). The model is started from rest with uniform stratification, and the main three physical parameters governing the dominant characteristics of the flow are the stratification, the bottom friction and the horizontal viscosity.

This NEMO configuration can be installed and used as follows:

Download the NEMO model

Prepare the SQB configuration

Compile the SQB configuration

Run the SQB configuration