Application of an Inverse Method to Coastal Modeling

Abstract

Free surface coastal models currently suffer from the difficulty of having to specify the global circulation during the initialization process and along the open boundaries. As an alternative to the long spinup periods, an original explicit approach based on inverse techniques has been developed. Data originating from in situ observations and/or ocean general circulation models are optimally interpolated over the small-scale grid in such a way that the tendency terms are reduced to physically consistent values. The errors on the ?true? tendencies and the truncated nonlinear term are evaluated to compute the model covariance. The observation covariance matrix is divided into two parts: the homogeneous, isotropic matrix calculated with a global energy spectrum; and a parameterized nonhomogeneous, nonisotropic matrix. The inverse method is applied to the study of the interaction of a barotropic alongshore current over a narrow canyon. The transient processes following the initialization are drastically reduced and the analysis field can efficiently be used in a flow relaxation scheme along the open boundaries.