大气季节内振荡的数值模拟比较研究

NUMERICAL SIMULATION AND COMPARISON STUDY OF THE ATMOSPHERIC INTRASEASONAL OSCILLATION

用国内外两个较好的大气环流模式、在观测海表温度的强迫下进行了长时间(1978—1989年)的数值积分,然后对数值模拟结果与NCAR/NCEP再分析资料进行比较分析,其结果清楚表明,模式模拟结果的均方根误差中有30%—40%是来自于模拟的大气季节内振荡的均方根误差。尤其是,大气季节内振荡模拟的均方根误差的分布形势与总的均方根误差的分布形势几乎完全一致。对热带地区大气季节内振荡动能的模拟结果与NCAR/NCEP再分析资料的比较分析表明,其差异也十分明显,说明模式对热带大气季节内振荡的模拟能力也还比较差。因此可以认为,大气季节内振荡在天气气候模拟中极为重要,而如何在数值模式中模拟好大气季节内振荡还需要进行很好地研究。

Daily mean outputs for 12 years （ 1978- 1989） from two general circulation models （the SAMIL-R42L9 developed in the LASG/Institute of Atmospheric Physics, Chinese Academy of Siences; and the CAM2.02 developed in the NCAR, USA） forced by the observed sea surface temperatures are analyzed and then compared with the corresponding NCEP/NCAR reanalysis data. The results clearly show that the root-mean square errors （RMSE） of the simulated intraseasonal oscillations （ISO） accounted for the 30 - 40 percent of the total RMSE, and particularly, the pattern of the RMSE of the simulated ISO was almost identical with that of the total RMSE. This means that the ISO and its description played an important role in the numerical simulation and prediction of weather and climate. The maximum RMSE of simulated ISO height at 500 hPa was shown in the middle latitude region, but there were also the larger RMSE of ISO wind at 850 hPa over the tropical western Pacific and tropical Indian Ocean. The maximum RMSEs of simulated ISO both in the 500 hPa height and the 850 hPa wind all occurred in the winter hemisphere. Differences between the simulated and observed （the NCEP/NCAR reanalysis data） ISO kinetic energy were very large in the tropics, meaning that the simulation of tropical atmospheric ISO was still poorer. Therefore, the ISO is of significance for the numerical simulation of weather and climate, and so, how to improve the ability of the GCM to simulate the ISO needs to be further studied.