摘要
In order to improve the practicality of spectral method and the efficiency of computation, the multi-spectrum method is proposed on the basis of multi-grid method. Coarse spectra are used to compute the slow nonlinear part (including physical process), while fine spectra are used to compute the fast linear part. This method not only can reduce computation time, but also can obtain computational efficiency similar to that from only fine spectra. Thus, it is an economical numerical method. Both explicit complete-square-conservation scheme and multispectrum scheme are used to improve IAP L 9 T 42 spectral climate models, with and without physical forcings respectively, and the advantage of reducing computation time is obtained satisfactorily. In order to overcome the difficulty that vapor equation is very sensitive to the change of time step, the square-conservation semi-Lagrangian scheme is used to solve vapor equation. Because the semi-Lagrangian scheme has the property of square-conservation, computational instability can be avoided. When time step becomes longer with the semi-Lagrangian Scheme, through numerical examples, the vapor transportation can be depicted objectively and the effect of precipitation simulation can be modified.
In order to improve the practicality of spectral method and the efficiency of computation, the multi-spectrum method is proposed on the basis of multi-grid method. Coarse spectra are used to compute the slow nonlinear part (including physical process), while fine spectra are used to compute the fast linear part. This method not only can reduce computation time, but also can obtain computational efficiency similar to that from only fine spectra. Thus, it is an economical numerical method. Both explicit complete-square-conservation scheme and multispectrum scheme are used to improve IAP L 9 T 42 spectral climate models, with and without physical forcings respectively, and the advantage of reducing computation time is obtained satisfactorily. In order to overcome the difficulty that vapor equation is very sensitive to the change of time step, the square-conservation semi-Lagrangian scheme is used to solve vapor equation. Because the semi-Lagrangian scheme has the property of square-conservation, computational instability can be avoided. When time step becomes longer with the semi-Lagrangian Scheme, through numerical examples, the vapor transportation can be depicted objectively and the effect of precipitation simulation can be modified.
