Characterization of error dynamics in a 3D coastal model of the Catalan sea using stochastic modelling

The structure and dynamics of errors in a 3D coastal model of the Catalan sea is characterized through stochastic modelling. Wind forcing and large scale circulation are identified as the main sources of model errors. Ensemble simulations perturbing the wind field and the model initial and open boundary conditions are performed. The dispersion of model trajectories in the ensemble allows us to characterize the errors structure and dynamics. Model errors induced by errors in the wind forcing are linear but non-stationary, while those induced by errors in the description of the large scale circulation are non-linear but stationary. The ensemble results are also used to characterize the error covariance spatial patterns through the use of multivariate EOFs. The capability of this EOF decomposition to control the model evolution is investigated using a reduced order optimal interpolation (ROOI) data assimilation scheme.