Application of an inverse method to coastal modeling

Free surface coastal models currently suffer from the difficulty of having to specify the global circulation during the initialization process and alo ng the open boundaries. As an alternative to the long spinup periods. an or iginal explicit approach based on inverse techniques has been developed. Da ta originating from in situ observations and/or ocean general circulation m odels are optimally interpolated over the small-scale grid in such a way th at the tendency terms are reduced to physically consistent values. The erro rs on the "true" tendencies and the truncated nonlinear term are evaluated to compute the model covariance. The observation covariance matrix is divid ed into two parts: the homogeneous, isotropic matrix calculated with a glob al energy spectrum; and a parameterized nonhomogeneous, nonisotropic matrix . The inverse method is applied to the study of the interaction of a barotr opic alongshore current over a narrow canyon. The transient processes follo wing the initialization are drastically reduced and the analysis field can efficiently be used in a Row relaxation scheme along the open boundaries.