Numerical Studies of Mesoscale Convective Systems Using a Cloud-Resolving Model

东亚的白乌季节的特点是非常潮湿的气候。在该地区，持续时间长，强降水系统偶尔发展，并造成大暴雨。它们被称为中尺度对流系统。本研究利用CReSS（the Cloud Resolving Storm Simulator）对中尺度对流系统进行了数值模拟试验，并与台湾和韩国的研究人员合作，在2002年对CReSS进行了改进，包括地图投影功能、侧边界条件的改进、多普勒雷达资料的同化等。利用改进后的CReSS进行了逐日天气预报试验和暖季中尺度对流系统的模拟试验。2003年，我们邀请了台湾和韩国的研究人员进行了合作实验，并在地球模拟器上进行了CReSS的优化，并对其性能进行了评估。结果表明，矢量运行率为99.4%，并行运行率为99.985%， ...更多信息 持续效率33%。利用地球模拟器上的CReSS软件，在水平分辨率为500m的120个节点（960个CPU）上，对多尺度的白乌锋面低压、水俣市局地暴雨、台风和日本海雪带云进行了数值试验。结果显示了单个对流单体的详细结构和降水系统的总体结构。对与白乌锋面有关的降水系统的多尺度结构也进行了较好的模拟。雪云带实验揭示了海上云带或云街的形成和发展过程。对台风RUSA造成的暴雨进行了预报试验，结果表明，当台风到达半岛南部时，螺旋带增强。这些结果表明，云分辨模式的计算对准确模拟一次暴雨过程是重要的。少

The Baiu season in East Asia is characterized by a very humid climate. In the area, long-lasting and intense precipitation system occasionally develop and cause a heavy rainfall. They are referred to as a mesoscale convective system. In this study, we performed numerical simulation experiments of mesoscale convective systems using CReSS (the Cloud Resolving Storm Simulator) in collaboration with researchers of Taiwan and Korea.In 2002, we improved CReSS ; map projection capability, improvement of the lateral boundary conditions, assimilation of Doppler radar data. Using the improved CReSS, we performed daily weather prediction experiment and simulation experiments of mesoscale convective systems in warm season. We also invited researchers of Taiwan and Korea and made collaborative experiments.In 2003, we performed optimization of CReSS to the Earth Simulator and evaluated its performance. The result showed that vector operation ratio is 99.4 %, parallel operation ratio is 99.985 % and … More sustained efficiency 33 %. Using CReSS on the Earth Simulator, we performed numerical experiments of multitscale Baiu frontal lows, the localized heavy rainfall in Minamata City, a typhoon and snow band cloud over the Sea of Japan.The experiment of the Minamata localized heavy rainfall was performed with the horizontal resolution of 500m using 120 nodes (960CPUs) of the Earth Simulator. The result showed detailed structure of individual convective cells and overall structures of the rainfall system. The multi-scale structures of the precipitation system associated with the Baiu front were also well simulated. The experiment of snow cloud band showed the formation and development of cloud bands or cloud streets over the sea. We also performed the prediction experiment of heavy rainfall caused by Typhoon RUSA and showed that the spiral band intensifies when the typhoon comes to the southern Korean Peninsula. These results show that computation using the cloud resolving model is important for the accurate simulation of a heavy rainfall. Less