FURTHER STUDIES OF NUMERICAL ERRORS ON THE INTEGRATION OF BAROTROPIC FLOW ON A SPHERICAL GRID
CALIFORNIA UNIV LOS ANGELES
Pagination or Media Count:
Using a spherical finite-difference grid system covering the hemisphere, numerical solutions of the non-divergent barotropic vorticity equation have be n obtained for periods up to 10 days by rela ation methods. In the case of analytic initial conditions, the solutions are sensitive to abrupt changes of the longitudinal mesh size in the regions of appreciable amplitude of the streamfunction tendency. A doubling of the longitudinal mesh size from 5 to 10 deg at 45 deg N produces a progressive tearing or shearing in the stream function which is quite noticeable at 10 days. When the grid variation is removed to 70 degrees N, however, the solutions at 10 day are free of this defect, although exhibiting the expected phase lag relative to the analytic solution. When applied to hemispherical barotropic prediction with actual 500 mb data, this spherical grid scheme appears to perform as satisfactorily as do conventional rectangular grid formulations.