Global atmospheric models are usually formulated upon latitude-longitude grids. Near the poles, these grids have disproportionately high resolution, which may severely constrain the time step of integration or require special filtering. Advection problems may also occur near the poles of such grids. Quite recently, a global conformal-cubic grid was devised by (1996). This grid avoids the disadvantages of latitude-longitude grids, but does require careful selection of numerical techniques to account for the eight vertices of the grid (McGregor, 1996).