近30 a山东首场暴雨的气候特征及环流形势

选取济宁地区1970—2014年11个国家级观测站45 a逐日降水资料，利用统计、天气诊断等方法，对济宁地区春季暴雨的时空分布特征、雨强特征、天气环流形势及主要影响系统进行了分析。结果表明：济宁地区春季暴雨空间分布差异比较大，暴雨区位于济宁中西部和东南部，微山地区春季暴雨日数最多，近45 a来济宁地区的春季暴雨日数呈缓慢上升趋势，特别是2003年开始春季暴雨发生的频次明显增多，最强暴雨日发生在2013年5月26日。基于春季大范围暴雨的天气形势及主要影响系统，归纳出济宁地区春季暴雨天气概念模型，模型显示大范围暴雨发生时，500 hPa中高纬地区多为东高西低环流形势，低层850 hPa低涡或暖切变线是主要影响系统；西南风或东南风低空急流为暴雨区输送水汽，副热带高压控制南海东部，使南支槽东移缓慢，以及中高纬日本海高压阻挡低涡、暖切变线东移，有利于强降雨的长时间维持；另外，暴雨发生时山东北侧或南侧常有高空急流存在，济宁上空为槽前脊后的高层辐散形势，地面上无明显西北路冷空气活动。

Climatic characteristics and main weather conceptual model of spring rainstorm in Jining during the past 45 years

According to the daily precipitation data of 11 national observatory stations in Jining area during the period of 45 years from 1970 to 2014, the temporal and spatial distribution characteristics, rain intensity characteristics, weather circulation situation and main influencing systems of spring rainstorms in Jining area were analyzed. The results show that the spatial distribution of spring rainstorms in Jining area is quite different from each other, and the rainstorm area is located in the midwestern and the southeast part of Jining. The number of spring rainstorm days in the Weishan area is the most in Jining. The annual spring rainstorms in Jining show a slow increasing trend, especially since the year 2003, the occurrence frequency of rainstorms has increased significantly, and the strongest rainstorm occurred on May 26, 2013. Based on the weather situation and the main influencing system of massive spring rainstorms, a concept model of rainstorm weather in Jining was developed. The model shows that when massive rainstorm occurs, mid and high latitude region at 500 hPa mostly has a weather situation of high in east and low in west; the 850 hPa low vortex or low-level wet warm shear line is the main system of wide range spring rainstorms. The model also shows that low level jet with southwest or southeast wind transports water vapor to the rainstorm area and the subtropical high pressure zone dominates eastern region of the South China Sea, which blocks the webtisr' s moving eastward, and makes the southwest airflow transport vapor to the Shandong for a prolonged time. The block of high pressure in mid-high latitude in the Sea of Japan makes low vortex or shear line move eastward slow, which helps maintain strong precipitation for a long time. Moreover, There are often high level jets in north and south sides of Shangdong when rainstorms occur, and the atomosphere above Jining shows the situation of high level divergence, and there is no obvious northwest-toward cold air acitivity on the ground.