Internal variability of the ocean generated by a stochastic forcing

In this study we investigate the internal variability of the ocean circulation under a stochastic perturbation of the freshwater flux. The ocean model we use in this study is a simple geostrophic model, which consists of a perfectly isolated rectangular basin with twelve layers in the vertical.
At the surface mixed boundary conditions are applied, i.e. a restoring condition for temperature and a prescribed freshwater flux.
If a stochastic perturbation is added to the freshwater flux the behaviour of the system displays an oscillating character with a characteristic period in the order of 100 years.