The Treatment of Lateral Boundary Conditions in Limited-Area Models: A Pragmatic Approach.

摘要

Mathematical models used to simulate or predict atmospheric behavior are limited in scope because of insufficient knowledge of the initial conditions and forcing functions. But these limitations are generally dwarfed by the limited capacity and power of even the largest and most powerful computers. Thus, where a solution is required with high resolution for some limited area of interest, it is often impractical to solve the model throughout the entire domain with the same uniformly high resolution. A pragmatic approach is proposed here which overspecifies the artificial lateral boundaries of a fine-mesh, limited-area, nested region and depends upon a high-order phase and amplitude restoring interpolation along with a high-order, but weak, smoothing operator to control noise and ensure versimilitude. The dynamic tests are carried out in the framework of a multilevel primitive equation model and show unequivocally the importance of correct phase information for the lateral boundaries of the fine-mesh region. The results obtained indicate that the simple procedure proposed here should yield satisfactory results in operational fine-mesh, limited-area models.