一次热带海洋对流云微物理过程的数值模拟

A NUMERICAL SIMULATION OF CLOUD MICROPHYSICAL PROCESSES OF A TROPICAL CONVECTIVE CLOUD

为了理解微物理过程以及次生对流云对热带对流云团发展演变过程的影响,利用二维云分辨模式对2006年1月20日靠近澳大利亚西北部的印度尼西亚暖池附近的一次对流云降水过程进行数值模拟,分析了对流云发展演变不同阶段各种微物理过程的特征,尤其对次生对流的形成以及并合过程进行了深入分析。结果表明:本个例所研究的热带对流云团具有发展速度快、云顶高度高等特点,冰相过程是降水形成的主要决定因素,主对流云消散阶段的下沉气流是次生对流生成的前提条件,加上温度场和湿度场的配合就能生成次生对流;次生对流不仅促进其他次生对流的形成,还能延长主对流云的生命史。

A tropical convective cloud in northwest Australia and in the vicinity of Indonesia warm pool on January 20th 2006 is simulated using a 2D cloud resolving model to investigate the influence of tropical convective clouds development by microphysical processes, and the occurrence of secondary convective clouds. The cloud microphysical processes, especially the formation of secondary convection and merging process, have been analyzed. The results show that the tropical convective clouds simulated here have a fast development and a high cloud top height; the ice-phase processes are the main process in the formation of precipitation; the prerequisite for secondary convection is the subsiding air around the main convective clouds and the suitable temperature and humidity field; and the secondary convection would promote the formation of other secondary convection and extend the vitality of the main convective clouds.