[目的]研究2010年8月3日晚至4日凌晨临沂一次局地大暴雨过程的成因.[方法]利用MICAPS天气图、NECP分析场实况资料、加密自动站资料和多普勒雷达产品等,从发生的天气背景、中小尺度特征以及中小尺度系统发生、发展物理机制等方面详细分析了2010年8月3日晚至4日凌晨临沂一次局地大暴雨、特大暴雨过程,探讨此次大暴雨过程的成因,并尝试从中找出一些短历时强降水发生的规律.[结果]此次局地大暴雨过程短时降水量大,局地性特点明显；主要影响系统为副热带高压、西风槽和地面中小尺度低压,是由不同尺度、不同高度的多个系统共同作用的结果.上冷下暖的不稳定层结蓄积了大量的不稳定能量,是强降水发生的基本条件；上空底层为辐合切变线,上空有一层深厚的西南一西北一偏东气流的垂直切变、湍流层；上下系统的共同作用触发了上升气流的产生,使不稳定能量得以释放；由于不稳定能量的释放,西北气流被切断消失后,上升气流使西南气流向上发展,与东风波相接形成新的垂直切变,是强降水持续时间较长的一个原因.副高边缘的西南气流是此次降水过程的水汽来源,为大暴雨的产生提供了充足的水汽供应.发展、增强中的系统会使系统的移动速度变慢,从而增大降水量,也是强降水维持时间较长的一个原因.[结论]该研究为今后的预报工作积累一定的经验.%[Objective]The research aimed to study formation reason of a local heavy rainstorm process in linyi from night on August 3 to early morning on 4th, 2010. [Method] Based on MICAPS weather chart, actual situation data of NECP analysis field, data of automatic encryption station and Doppler radar product, a local heavy rainstorm and extra torrential rain process in Linyi from night on August 3 to early morning on 4th, 2010 was detailedly analyzed from weather background, meso and small-scale characteristics, physical mechanisms of occurrence and development of meso and small-scale systems. The formation reason of heavy rainstorm process was discussed. Moreover, we tried to find some occurrence rules of short-time strong precipitation. [ Result] The local heavy rainstorm process had big short-time rainfall and obvious local characteristic. The main influence systems were subtropical high, westerly trough and meso and small-scale ground low pressures. It was affected by many systems which had different scales and heights. The upper-cold-down-warm unstable stratification accumulated a large number of unstable energy, which was basic condition of strong precipitation occurrence. It was convergence shear at the bottom layer of airspace. The vertical shear and turbosphere of deep and thick southwest-northwest-easterly airflow were at airspace. The common effect of up and down systems triggered generation of updraft, and made unstable energy release. For the release of unstable energy, after northwest airflow was cut off and disappeared, the updraft made southwest airflow develop upward. It linked with easterly wave to form new vertical shear, which was one reason of long duration of strong precipitation. The southwest airflow at the edge of subtropical high was water vapor source of precipitation process, which provided sufficient water vapor supply for generation of heavy rainstorm. The system which was developing and strengthening would make moving speed of system slow down. Then, the rainfall increased. It was one reason of long duration of strong precipitation. [ Conclusion] The research accumulated certain experience for forecast work in future.
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