淮河流域(河南段)连续性暴雨天气分型及环流背景

Classification and Circulation Background of Sustained Rainstorms in Huaihe River Basin (Henan Section)

利用19812016年68月河南省淮河流域64个国家自动观测站逐日2020时日降水量资料、常规高空探测和地面观测资料等对淮河流域连续性暴雨时间分布特征、影响系统等进行分析和天气分型,结果表明:1)36年淮河流域共发生45次连续性暴雨,2000年的最多,19982008年是高发期,近10年较少,年出现次数无明显减少趋势,存在2~4年和4~6年两个周期;7月连续性暴雨次数最多,6月的最少,旬分布呈正态分布;最长连续时间5天,连续2天的最多。2)影响系统主要有切变线和高低空急流,高空急流在方向转换的过程中,降水有24h左右的减弱期,低空急流有明显的日变化特征,夜间加强,白天减弱。3)连续性暴雨按照500hPa影响系统,分为低槽型、副高边缘型、西北低涡型三类。4)以不同类型的3次典型连续性暴雨为例,从大尺度环流背景、高度距平场、水汽输送、高低空急流等方面探讨了连续性暴雨的维持成因,3次连续性暴雨的发生与异常的500hPa大气环流、高低空急流、切变线和持续偏强的水汽输送等有关。

By using the daily 20 20 h,that covering from June to August of 1981 2016 , precipitation and routine sounding data of 64 national automatic weather stations of Huaihe River Basin in Henan province, the temporal and spatial distribution characteristics,influence systems of sustained rainstorms, and so on are analyzed and further classified in synoptic patterns. Results are as follows. 1)There were a total of 45 sustained rainstorms in 36 years over Huaihe River Basin, most of which have occurred in 2000, with a high incidence period of 1998 2008 but rare occurrence during last 10 years,and the annual occurrence frequency has no obvious decreasing trend with two periodic cycles as the 2 4 and the 4 6 years;the sustained rainstorms mostly occur in July but least occur in June, the 10-day characteristic has a normal distribution;and the longest sustained time period is 5 days while the sustained time period of 2 days has the highest occurrence frequency. 2)The influence systems of sustained rainstorm mainly contain the shear lines and the upper/lower level jets, and during the direction transformation of the later, precipitation has a weakened period of around 24 hours;the lower jet has an obvious diurnal variation with intensified at night and weakened at daytime. 3)According to the 500 hPa influence systems, the sustained rainstorm can be distinguished into 3 patterns as the low-trough, the subtropical-high marginal and the northwest low eddy. 4)As referenced to 3 typical sustained rainstorms of the on going distinguished patterns, maintenance causes of the sustained rainstorms have been discussed from the view of large scale background, anomaly field, vapor transportation and upper/lower jets, while the occurrence of the 3 typical cases is found to be related to 500 hPa atmospheric circulation anomaly, upper/lower jet, shear line and sustaintiously intensified vapor transportation and so on.