庐江暴雨气候特征及一次持续性暴雨过程分析

Climatic Characteristics of Heavy Rain and Analysis of a Sustained Heavy Rain Process in Lujiang River

利用2008—2021年庐江气象观测站观测资料,分析其暴雨气候特征,选取2020年7月18—19日大暴雨过程,对其环流形势、低层切变、地面系统、暴雨条件等进行天气形势综合分析。结果表明:(1)2008—2021年庐江暴雨日数累计61 d,其中暴雨日数大于100 mm的有17 d,年均暴雨日数为4.4 d,其年际变化呈上升趋势。暴雨日数的月变化呈现单峰型,主峰在6月,大暴雨日数主峰在6—7月,平均暴雨强度为81.8 mm/d;(2)庐江气象观测站气温、水汽压不断上升预示着中低层暖湿气流不断加强,气压不断下降预示着高空有低槽移入,需要高度警惕强降水天气过程出现的可能性;(3)西太平洋副热带高压脊线稳定维持、500 hPa短波槽东移、槽区上的短波同位相叠加、槽前与副高边缘的西南暖湿气流共同作用、中低层急流、水汽辐合和抬升等是形成庐江2020年7月18—19日持续性大暴雨过程的主要原因。

Based on the observation data of Lujiang Meteorological Observation Station from 2008 to 2021,the characteristics of the rainstorm climate were analyzed.The circulation,low-level shear,surface system and rainstorm conditions of the rainstorm during July 18-19,2020 were comprehensively analyzed.The results showed as follows:(1)The total number of rainstorm days in Lujiang from 2008 to 2021 was 61 days,of which 17 days were greater than 100 mm,and the average annual rainstorm days were 4.4 days.The interannual variation of rainstorm days showed an increasing trend.The monthly variation of rainstorm days presents a single-peak pattern,with the main peak in June.The main peak of rainstorm days was in June and July,and the average rainstorm intensity was 81.8 mm/d.(2)The rising temperature and water pressure in this station indicates the strengthening of warm and humid air in the middle and low levels,and the falling pressure in this station indicates that there was a low trough in the upper air,which requires high vigilance against the possibility of heavy precipitation weather process.(3)The stable maintenance of the Western Pacific subtropical ridge,the eastward shift of the 500 hPa short-wave trough,the superposition of the short-wave isophase over the trough,the interaction of the southwest warm and humid air in front of the trough and the edge of the subtropical high,the mid-low level jet stream,water vapor convergence and uplift were the main reasons for the sustained heavy rain in Lujiang River from 18 to 19 July 2020.