A NEW REGION-SPLIT METHOD
一种新的区域分离法

A new region-split method is established on the basis of the characteristicdirection method, which is easy to be implemented on the barotropic shallow water modelwhose region is the Sphere or Hemisphere. This method has three advantages. First,theboundary conditions on the common boundary of the split regions need no special treatment.because the boundaries of the split regions can tally naturally on the common boundaryNext,using the natural periodic boundary condition along the meridional direction in thenew method,CPU time can be greatly reduced due to the increase of the time step nearthe Poles.Last,though there exist two split regions in this method,the key computationsare implemented in the original integration region. Only the treatments of the results in thetwo split regions are different. Thereforel the calculations are convenient.