Stochastic parametrization of EOS (STO)

The stochastic parametrization module aims to explicitly simulate uncertainties in the model. More particularly, Brankart [2013] has shown that, because of the nonlinearity of the seawater equation of state, unresolved scales represent a major source of uncertainties in the computation of the large scale horizontal density gradient (from T/S large scale fields), and that the impact of these uncertainties can be simulated by random processes representing unresolved T/S fluctuations.

The stochastic formulation of the equation of state can be written as:

where is the reference pressure depending on the depth and and are a set of T/S perturbations defined as the scalar product of the respective local T/S gradients with random walks :

are produced by a first-order autoregressive processes (AR-1) with a parametrized decorrelation time scale, and horizontal and vertical standard deviations . are uncorrelated over the horizontal and fully correlated along the vertical.

Gurvan Madec and the NEMO Team

NEMO European Consortium2017-02-17