TESTS OF A 2-GRID WORLD OCEAN MODEL

A numerical method for a global ocean model which does not need artifi cial islands or Fourier filtering at high northern latitudes is descri bed. The method uses two grid schemes: one, for most of the ocean, is regular latitude-longitude; the other uses a rotated pseudo-latitude a nd pseudo-longitude scheme with the poles in the equatorial Pacific an d Indian Oceans. The two grids defined by these coordinates communicat e in the equatorial Atlantic. A method for communicating information b etween these is described briefly, and a test of the method is made us ing equatorial Kelvin and Rossby waves. The two-grid method is found t o perform excellently (when compared with a similar problem using a si mple latitude-longitude grid), so that the method may be considered va lidated for future use in a global model.