三江源地区一次典型暴雨过程研究

Study on a Typical Rainstorm Process in the Sanjiangyuan Region

利用常规气象观测资料对发生在三江源区的一次典型暴雨过程通过天气学诊断分析方法进行了研究。研究表明:(1)这次暴雨是一次短时强降水过程,暴雨中心位于玛沁县;(2)受台风“摩羯”和“珊珊”的影响,副热带高压西伸加强,三江源东部地区有高压外围的暖湿气流和从新疆南下的西北冷空气在此交汇;(3)500 hPa高原涡是暴雨发生的主要影响系统,200 hPa由于冷空气影响,青海东部是辐散下沉气流;(4)暴雨发生前,三江源暴雨区是假相当位温梯度的负值区,为对流不稳定层结;有水汽从黄海、日本海和日本附近太平洋输送到暴雨区,使得低层水汽充足,并处于高层辐散、低层辐合同时有上升运动配合的不稳定配置下,为这次降水提供了有利的动力、热力和水汽条件。

Based on the conventional meteorological observation data,a typical rainstorm process in the source area of three rivers is studied by the method of synoptic diagnosis and analysis.The results show that:(1)the rainstorm is a short-term heavy rainfall process,and the rainstorm center is located in Maqin County;(2)Under the influence of typhoons“Capricorn”and"Shanshan",the subtropical high extends to the West and strengthens.In the eastern part of the source of three rivers,there is a warm and humid air flow around the high pressure and the northwest cold air from Xinjiang to the south;(3)500 hPa plateau vortex is the main influence system of rainstorm.Due to the influence of cold air at 200 hPa,there is a divergent downdraft in the east of Qinghai;(4)Before the rainstorm,the rainstorm area of Sanjiangyuan is a negative area of pseudo equivalent potential temperature gradient,which is convective unstable stratification;Water vapor is transported from the Yellow Sea,the sea of Japan and the Pacific Ocean near Japan to the rainstorm area,making the low-level water vapor sufficient,and under the unstable configuration of highlevel divergence,low-level convergence and upward movement,which provides dynamic,thermal and water vapor conditions for this precipitation.