摘要: A quasi-geostrophic model has been formulated using the potential vorticity as the only time dependent model variable. The model consists of a two-dimensional prognostic equation of the hyperbolic-type and a three-dimensional diag... 展开 A quasi-geostrophic model has been formulated using the potential vorticity as the only time dependent model variable. The model consists of a two-dimensional prognostic equation of the hyperbolic-type and a three-dimensional diagnostic equation of the elliptic-type. This formulation permits the model equations to be solved more efficiently and perhaps also more accurately than any other formulation that has been in operational use. Preliminary numerical tests using observed data, in connection with comparison case studies of the effect of discretization error and the influence of the lower boundary conditions, indicate that the model is realistic enough to warrant further tests for possible operational use. 收起