由于西北太平洋副热带高压、2023年第5号台风"杜苏芮"、第6号台风"卡努"等共同作用,2023年7月29日08时—8月2日08时(北京时)华北地区发生极端特大暴雨,造成了重大社会影响.利用中国气象局国家气象信息中心提供的国家级气象站逐小时降水资料,分析了此次特大暴雨过程中的小时强降水(Hourly Heavy Rainfall,HHR)时空分布特征,并对不同历时类型强降水事件(Heavy Rainfall Event,HRE)的统计特征进行了对比.结果表明:1)此次特大暴雨HHR强度高、局地性明显,其对总降水量的贡献超过20％,北京西部、河北中部和西南部等太行山东麓为HHR降水量大值区和降水频次活跃区,双台风将水汽源源不断地输送到华北平原,受到太行山等山脉阻挡抬升,利于HHR增幅和持续.2)HHR降水量、降水频次经历6次峰值后减弱,其中第3次峰值时段的HHR降水量最大、降水频次最多、持续时间最长;而在"杜苏芮"残涡螺旋影响、暖式切变线和偏东风影响以及偏南或西南急流影响的3个主要降水阶段中,"杜苏芮"残涡螺旋影响阶段HHR最为活跃,共发生257次HHR,HHR最大降水量达73.5 mm.3)在3种类型HRE中,长历时(＞12 h)最多,占比54.5％,短历时(1～6 h)次之,占比32.9％,中历时(7～12 h)最少,占比12.6％;长历时HRE降水量多＞180 mm,短历时、中历时HRE的降水量多为[20,60)mm;HRE的最大降水量表现为短历时＜中历时＜长历时,而最大降水强度表现正相反,3种历时HRE的最大小时降水量多为[20,30)mm.4)不同类型HRE降水量、频次和平均降水强度的空间分布显示,长历时HRE因频次高于短历时和中历时,加之历时长,其降水量也高于后两种类型,北京、河北等地是长历时HRE降水量和频次大值区.
Temporal and spatial distribution characteristics of hourly heavy rainfall of the"23.7"heavy rainstorm event in North China
Amidst the backdrop of global warming,rainstorms have become increasingly frequent in North China,posing significant threats to both the socio-economic fabric and health and safety of the population.The convergence of the subtropical high over the northwestern Pacific and Typhoons"Dussuri"(No.5)and"Kanu"(No.6)in 2023 precipitated an extreme rainstorm event in North China from 08:00 BST on July 29 to 08:00 BST on August 2,2023,resulting in considerable social disruption.Utilizing hourly precipitation data from national meteorological stations provided by the National Meteorological Information Center of the China Meteor-ological Administration,this study analyzes the temporal and spatial distributions of hourly heavy rainfall(HHR)and statistically compare three types of heavy rainfall events(HREs)with varying durations to elucidate their characteristics.The findings indicate that:(1)HHR during this event exhibited high intensity and localized pat-terns,contributing over 20％to the total precipitation.Areas such as the eastern foothills of the Taihang Mountains,including western Beijing and central and southwestern Hebei,recorded the highest precipitation a-mounts and the most active precipitation frequencies.The dual typhoons facilitated sustained water vapor transport to the North China Plain,which was enhanced by orographic lifting by the Taihang Mountains,promoting the per-sistence and intensification of HHR.(2)HHR experienced 6 periods,with the third peak showing the highest cu-mulative precipitation,frequency,and longest duration.During the stages influenced by the"Dussuri"residual vortex,warm shear lines,and easterly winds,as well as southerly or southwestern jets,HHR was most active dur-ing the stage associated with the"Dussuri"residual vortex,totaling 257 occurrences with a maximum precipitation of 73.5 mm.(3)Among the three HRE types,long-duration events(＞12 hours)were most fre-quent,accounting for 54.5％,followed by short-duration events(1-6 hours)at 32.9％,and medium-duration e-vents(7-12 hours)at 12.6％.Precipitation amounts for long-duration HREs typically exceeded 180 mm,while those for short and medium durations are mostly ranged from 20 to 60 mm.(4)Spatial analyses show that long-duration HREs had higher frequencies and precipitation amounts compared to shorter events.Beijing and Hebei were particularly prone to high precipitation amounts and frequencies during long-duration events.This study un-derscores critical role of the Taihang Mountain's terrain in influencing HHR during heavy rainstorm events in North China,suggesting that the mechanisms driven by refined terrain features warrant further detailed investiga-tion.Future studies could employ numerical simulation experiments to delve deeper into these dynamics.
North Chinaheavy rainstormhourly heavy rainfallheavy rainfall eventspatial and temporal distri-butiontyphoonterrain
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