A research on the interaction between baiu front and tropical cyclone and mesoscale organization of convection

建立了一个能较好地模拟百雨锋、热带气旋和中尺度有组织对流的数值模式。为了改进中尺度对流分解模式(Yamasaki，1986)中积云尺度的参数化，将积云尺度云水作为预报变量。另一个改进是，由于处理了积云对流的中尺度组织，因此没有使用Arakawa和Schubert(1974)在云参数化中使用的很小云量的假设。将该模式应用于与百雨锋和热带气旋相关的云团，并与过去提出的不同参数化方案的几个模式的结果进行了比较。结果表明，新的模式能更真实地模拟出与白云锋面和热带气旋中尺度结构相关的云尘。对于白云锋面与热带气旋的相互作用，对白云锋面以南有热带气旋和无热带气旋两种情况进行了数值试验。研究发现，热带气旋的存在增加了与百度锋面有关的雨量。阐明了它的增强过程和机理，并利用非静力积云尺度分辨模式进行了数值实验。通过改进冰相参数化，特别是改进了云冰和冰粒的生成速率和过程，更好地模拟了热带气旋的眼壁。发展了另一种可有效用于并行计算机的云模型。该模式可以成功地模拟出一个与热带气旋和龙卷风相关的超级单体。

A numerical model was developed that can well simulate Baiu fronts and tropical cyclones and mesoscale organized convection in these, phenomena. In order to improve cumulus-scale parameteriztion in the mesoscale-convection- resolving- model (Yamasaki, 1986), cumulus-scale cloud water was treated as a prognostic variable. Another improvement is that an assumption of a very small cloud fraction, which has been used in cloud parameterization of Arakawa and Schubert (1974), was not used because mesoscale organization of cumulus convection is treated. The model was applied to cloud clusters associated with baiu fronts and tropical cyclones and compared with results from several models with different parameterization schemes proposed in the past. It was found that a more realistic simulation could be made with a new model for cloud dusters associated with the baiu front and mesoscale structure of tropical cyclones.As for interaction of a baiu front with a tropical cyclone, numerical experiments were performed for two cases with and without a tropical cyclone to the south of the baiu front. The rainfall associated with the baiu front was found to be enhanced by the presence of a tropical cyclone. The process and mechanism for its enhancement were clarified.Numerical experiments were also made with the use of a non-hydrostatic cumulus-scale resolving model. By improving the ice phase parameterization, particularly generation rates and processes of the cloud ice and graupel, an eyewall of a tropical cyclone was better simulated. Another cloud model that can be efficiently used for a pararell computer, was developed. The model could simulate successfully a supercell associated with a tropical cyclone and a tornado in it.