In order to validate the numerical results we have performed a Lagrangian comparison of ORCA with two other general circulation models of the global ocean: GIM (Global Isopycnal model - MICOM) and OCCAM in collaboration with B. Marsh (SOC, UK) and S. Drijfhout (KNMI, NL).

The upper-branch solution for all three models is very similar as can be seen from the figures below.

The model differences are due to different model configurations, choice of simulation parameters, and Lagrangian time sampling. For example, the big difference in amplitude for the return flow of GIM is probably mainly due to the NADW drift observed in GIM (results are here for year 50 of the run) that is absent in ORCA (robust diagnostic simulation).

Despite the various differences between models results, the TAS to EQATL contribution is practically equal for all the simulations (3 Sv).