Analysis and Numerical Simulation of the Cross Equatorial Flow of 1991
对1991年全球越赤道气流的分析和数值模拟

The global cross equatorial flow (hereafter referred to as CEF) of 1991 was analyzed It has been found that both for the low- or high-level of the atmosphere, CEF has close relations with the antisymmetric diabatic heating In the monsoon regions the heating varies with seasons and has opposite signs in winter and summer; in the trade wind regions the sign of heating varies little with seasons, but the variations in intensity and extent are evident With the data in the spring of 1991 as initial conditions, three numerical simulations have been carried out by using the T21L5 spectral model The results show that inclusion of heating without orography (S1), or of orography without heating in the model (S2), there are obvious disagreements with observations in the simulations In the former case, the locations of the main flows are simulated well, but their intensities are quite weak compared with those of the observed ones In the latter case, irrespective of their locations or intensities, the results are not satisfactory However, if heating and orography are both incorporated in the model (S3), the simulation is fairly in agreement with the observation except in certain districts or details Finally, theoretical analyses and interpretations of the above results have been presented The results show that when diabatic heating and orography are both included in the model, not only linear actions, but also nonlinear interactions between them exist Therefore, the impact of S3 is much greater than that of S1 or S2 on the simulation