达州极端短时强降水特征及物理量指标分析

Analysis of the Characteristics and Physical Quantity Indicators of Extreme Short-time Severe Precipitation in Dazhou

【目的】为提高达州极端短时强降水预报准确率。【方法】利用常规气象观测资料,对2013—2022年达州极端短时强降水特征、环流背景和物理量指标进行统计分析,针对物理量指标设定相应阈值并进行检验。【结果】达州极端短时强降水年极值8月出现最多,年极值天气学类型分为高空低槽型和副高控制型2种;极端短时强降水集中出现在盛夏(7—8月),峰值出现在8月,凌晨到早上为易发时段;极端短时强降水站次空间分布总体呈南多中北部少特征;K指数、SI指数、抬升指数LI、Δθse_(850~500)、ΔT_(850-500)、Q_(700)及Q_(850)等物理量参数对极端短时强降水均具较好的指示意义,当同时满足设定的相关阈值时,极端短时强降水预报准确率较高,但此时漏报率也有所增加。【结论】对极端短时强降水的特征和环流背景进行分析,结合设定的物理量指标阈值,有利于进一步开展当地极端短时强降水潜势预报。

To improve the accuracy of extreme short-time severe precipitation forecasting in Dazhou,Sichuan Province,this study utilized conventional meteorological observation data and conducted a statistical analysis of the characteristics,circulation background and physical quantity indicators of extreme short-time severe precipitation in Dazhou from 2013 to 2022.Meanwhile,the corresponding thresholds were set and tested for these physical indicators.The results indicate that the annual extreme values of extreme short-time severe precipitation in Dazhou occur most frequently in August,with two main synoptic patterns,that is,high-altitude trough and subtropical high control.Extreme short-time severe precipitation is concentrated in midsummer(July-August),peaking in August,with wee hours to early morning being the most susceptible period.The spatial distribution of stations experiencing extreme short-time severe precipitation generally exhibits a pattern of more in the south but fewer in the central and northern regions.Physical quantity indicators such as the K-index,SI-index,lifting index(LI),Δθse_(850-500),ΔT_(850-500),Q_(700),and Q_(850) all demonstrate good predictive significance for extreme short-time severe precipitation.When these parameters simultaneously meet the set thresholds,the accuracy of extreme short-time severe precipitation forecasting is relatively high,but with a concurrent increase in missing report.The analysis of the characteristics and circulation backgrounds of extreme short-time severe precipitation,combined with the set thresholds for physical parameters,is conducive to further enhancing the potential forecasting of local extreme short-time severe precipitation.