A Numerical Scheme to Treat the Open Lateral Boundary of a Limited Area Model

Abstract

A numerical scheme to treat the open lateral boundary of a limited-area primitive equation model was formulated. Although overspecification of the boundary condition is inevitable in the pointwise boundary setting, the scheme was designed to keep the overspecification to a minimum degree. To impose the boundary conditions, a damping technique was used. Special care was taken to deal with the boundary layer winds at the lateral boundary. The above scheme is most suitable when gravity waves do not prevail in the vicinity of the open boundary. The scheme was tested in the numerical integrations of prognostic equations for a Haurwitz-type wave. Experimental results are presented which indicate the utility of the proposed method.