北京气候中心大气环流模式对季节内振荡的模拟

Simulations of the tropical intraseasonal oscillations by the AGCM of the Beijing Climate Center.

对北京气候中心大气模式(BCC AGCM2.0.1)模拟热带季节内振荡的能力进行了检验。北京气候中心新一代气候模式(BCC AGCM2.0.1)是在原中国国家气候中心模式的基础上参考NCAR CAM3改进形成的。新模式中引进了一个新的参考大气和参考面气压。因此原模式的预报量中的气温(T)和地面气压(p_s)则变为它们对参考大气气温的偏差和对参考面气压的偏差。模式还加入了新的Zhang-Mcfarlane对流参数化方案,并对其参数计算方法进行调整和改进。此外还对模式边界层处理、雪盖计算等进行了改进。上述模式在实测的月海温作为下边界条件的情况下运行52年(1949年9月—2001年10月)。然后对运行结果中的季节内振荡的状况进行分析,主要结果如下:NCAR CAM3模式模拟热带季节内振荡的能力很差,主要表现在模拟的热带季节内振荡强度很弱;东移波与西移波的强度很接近,而实际观测中是东移波的能量要远大于西移波;季节内振荡的季节变化及空间分布与观测相差很远。北京气候中心大气模式(BCC AGCM2.0.1)模拟热带季节内振荡的能力有显著的提高。模拟的热带季节内振荡很明显,强度接近于观测结果;模拟东移波的能量要大于西移波,这与观测较为一致;季节内振荡的季节变化和空间分布与观测相差不大。总的来看,BCC AGCM2.0.1模式在模拟热带季节内振荡方面比CAM3模式有明显的改进。

The performance of the BCC（Beijing Climate Center） AGCM（Atmospheric General Circulation Model version 2.0.1） in simulating the tropical intrascasonal oscillations（TIO） is examined in this paper.The simulations are validated against observation and also compared with the NCAR CAM3（Community Atmosphere Model,Version 3）.The BCC AGCM2.0.1 is developed based on the original BCC AGCM（version 1） and NCAR CAM3.A new reference atmosphere and reference pressure are introduced in to the model.Therefore,the original prognostic variables of temperature and surface pressure become their departures from the reference atmosphere.A new Zhang-Mcfarlane convective parameterization scheme is incorporated into the model with a few modifications. Other modifications include those in the boundary layer process and snow cover calculation. All simulations are run for 52 years from 1949 to 2001 under the lower boundary conditions of observed monthly SST.The tropical intrascasonal oscillations from the model are analyzed.The comparison shows that the NCAR CAM3 model has a poor performance in simulating the TIO.The simulated strength of the TIO is very weak.The energy of the eastward moving waves is similar to that of the westward moving waves in CAM3.While in observation the former is much larger than the latter.Seasonal variations and spatial distributions of the TIO produced by CAM3 are also much different from the observation.The ability of the BCC AGCM2.0.1 in simulating the TIO is largely improved.The simulated TIO is evident.The sthength of the TIO produced by the BCC AGCM2.0.1 is close to that of the observation.The energy of eastward moving waves is much stronger than that of the westward moving waves.This is close to the observation.There is no significant difference in the seasonal variations and spatial distributions of the TIO between the BCC model simulations and the observation.In general the BCC model is better than the CAM3 in simulating the TIO.