2006年6月6—7日福建特大暴雨数值模拟和诊断分析

采用PSU／NCAR等共同研制的新一代细网格WRF（WeatherResearchandForecasting）中尺度数值模式，对2006年6月6-7日福建地区出现的一次特大暴雨过程进行了数值模拟，并利用模式输出的高分辨率动力协调资料进行了初步诊断分析。结果表明，中尺度低涡是本次暴雨过程的主要影响系统之一，低涡的时空演变特征与暴雨中心的移动和雨强的变化相一致。暴雨中心的强上升运动及低层辐合、高层辐散的配置有利于中尺度对流系统的发生发展，高低空急流耦合是此次强降雨爆发的重要机制。暴雨区域850hPaθse场呈现典型的“Ω”型，高湿能条件的维持，保证了强降雨过程的能量供给，是强降雨持续的重要条件。暴雨中心位于最大垂直速度中心附近，暴雨区两侧存在垂直的次级环流，对流层中低层负湿位涡区、高层正湿位涡区的配置有利于造成较强烈的中尺度上升运动。

Numerical Simulation and Diagnostic Analysis of a Heavy Rainfall in Fujian during 6-7 June 2006

A heavy rainfall process during 6--7 June 2006 in the Fujian area is simulated by the finemeshed WRF mesoscale numerical model developed by multi-agency of USA, and a concept model is also constructed. The analysis of the output data indicates that the mesoscale low-vortex was one of the dominant systems in the process and its spatial and temporal evolution characteristics were in accord with the movement and rainfall rate of precipitation center. The disposition of the intensive ascending motion at the center of the rainstorm, and the upper-level divergence over the lower-level convergence were very conducive to the generation and development of mesoscale convective systems. The 850 hPa θac appears a typical ＂Ω＂ pattern, where high moisture and energy kept the rainfall maintaining and strengthening. The non-homogeneous convergence field located along the low-level shear line, and the center of the rainfall was adjacent to the maximum vertical velocity. There existed vertical secondary circulations in the two sides of the rainstorm area, suggesting that the interaction of the LLJ and ULJ was the important mechanism of the outbreak of the heavy rain. Besides, the positive moist potential vorticity（MPV） in the upper troposphere aloft the negative MPV in the lower troposphere was also conducive to the generation of strong mesoscale ascending motion.