华南前汛期一次大暴雨过程的扰动位涡反演与数值研究

利用NCEP 1°×1° 6h再分析资料、位涡反演和数值试验方法，分离与不同物理过程有关的扰动位涡进行反演诊断．在此基础上移除模式初始场中包含的与不同物理过程有关的扰动位涡反演的平衡场进行敏感性试验．对2006年5月21—22日一次热带扰动系统北上在广东珠江三角洲地区引发的大暴雨天气过程进行了探讨。结果发现：对流层中低层与潜热释放有关的正扰动位涡是影响热带扰动形成、维持及发展的主要因子之一；与潜热释放无关的扰动位涡对副热带高压的形成和维持有重要作用，影响热带扰动系统的移动路径；边界层内的扰动位涡有利于南海热带洋面北上气旋性扰动的发生、发展与维持；中高层扰动位涡对气旋性扰动系统的直接影响很小；下边界扰动位温不利于气旋性扰动系统的形成、维持与发展。数值敏感性试验表明，初始场中包含的与不同物理过程有关的扰动位涡在暴雨数值模拟中有重要作用，它们不同程度地影响热带扰动的强度、活动路径的模拟．并影响暴雨强度和落区；与非绝热物理过程有关的扰动位涡很大程度上影响暴雨强度，而与非绝热物理过程无关的扰动位涡很大程度上决定暴雨落区。

A PV Inversion Diagnosis and Numerical Research on an Extreme Heavy Rain in Southern China Flooding Season

Based on NCEP 1°×1° every-6-hour reanalysis data, potential vorticity inversion methodology and numerical sensitivity experiment, a heavy rain in Zhujiang Delta of Guangdong Province on 21-22 May 2006 triggering by a tropical perturbation is investigated by the PV separation and inversion and removing its related balanced field from model initial data. The results are as follows. The positive PV perturbation related to the latent release heating in the mid-lower troposphere is a main factor influencing the formation, maintenance and development of the tropical disturbance. The PV disturbance unrelated to the latent release heating is important in the formation and maintenance of the subtropical high and influences the moving path of the tropical system. The PV perturbation in the boundary layer is somewhat conducive to the generation, development and maintenance of the cyclonic disturbance over the Southern China Sea, but the lower boundary potential temperature perturbation is not. Little is the direct effect of the PV perturbation in the mid-upper troposphere on the tropical system. The sensitivity experiment shows that the PV perturbation associated with different physics processes included in the model initial field is very important in the heavy rain simulation and influences the simulation of the tropical disturbance intensity and moving path and therefore the influences heavy rain intensity and location to a different degree. The PV perturbations related to diabatic heating effect the heavy rain intensity to a large extent, while those unrelated to diabatic heating determine the heavy rainfall location.