用简单海气耦合模式研究西太平洋暖池的形成机制及其对大气扰动的影响——Ⅱ.西太平洋暖池的形成过程及其对大气扰动的影响的数值模拟(英文)

On Study of Formation of the West Pacific Warm Pool and Its Effect Upon the Atmospheric Disturbance in a Simple Coupled Ocean Atmosphere Model Part Ⅱ. The simulation of the West Pacific Warm Pool formation and its effect upon the atmospheric intr

用第一部分建立的简单海气耦合模式，研究了西太平洋暖池的形成过程及其对大气扰动的影响。模式可以较好地模拟出热带太平洋海温“西高东低”的分布，以及“暖池”附近ＳＳＴ的水平梯度较小等特征。在垂直方向上海洋混合层深度关于赤道呈准对称的“马鞍”型分布特征也可以从理论上和数值模拟的结果中得到证实。模式中“暖池”形成的时间尺度大约为半年多，大气中凝结潜热的释放有利于“暖池”的快速形成，提高凝结潜热的释放的效率，“暖池”形成的时间就缩短。“暖池”形成的动力学机制是海气耦合系统中海洋Ｒｏｓｓｂｙ波振幅的不稳定增长所致。“暖池”区海气之间的耦合作用确实对热带大气的季节内振荡产生影响。当海气之间进行耦合作用时，可以模拟得到扰动传播的周期大约为５０多天（ｄ），与实际观测相吻合。提高海气之间的耦合强度会降低扰动的传播速度，使传播周期明显加大。当不考虑海气之间的耦合作用时，模拟得到的扰动传播周期明显地比用耦合模式得到的要小。

The formation of the West Pacific Warm Pool (WPWP) and its effect upon the tropical atmospheric intraseasonal oscillation are investigated by using the established coupled ocean atmosphere model in Part I of this paper. Some simulated features of the tropical Pacific Ocean in which the SST horizontal distribution is “west high, east low”, and the horizontal SST gradient near the WPWP region is smaller than that of other regions are in agreement with observations. The feature that the depth of the oceanic mixed layer has the characteristics of a quasi symmetric saddle type about the equator vertically can be identified both from the theoretical analysis and simulated restults. The forming time of the warm pool in the model is about half a year. The release of atmospheric condensational latent heating favors to the fast forming of the warm pool. When the efficiency of condensational latent heating is enhanced, the forming time of the warm pool is shortened. The mechanism of warm pool formation is the unstable amplification of the oceanic Rossby wave. The coupling of the ocean and the atmosphere has a significant effect upon the tropical atmospheric intraseasonal oscillation. When the ocean and the atmosphere couple, the simulated period of the tropical atmospheric oscillation is about 50d. The enhancing of the coupling intensity of the ocean and the atmosphere slows down the phase speed and enlarges the period obviously. When the coupling of the ocean and the atmosphere is not considered in the model, the simulated period is obviously smaller than that of the coupled model.