Characteristics of Warm-Sector Rainstorms in the Middle and Lower Reaches of Yangtze River
Chen Xiaoxiao
Huang Zhiyong
Yao Yao
Tang Xingzhi
Ju Yingqin
Gu Yonggang
Li Liuyi
Abstract：Based on the hourly observation data and high-altitude situation field of 359 national sta-tions from April to September of 2000-2019,the NCEP reanalysis data and the best typhoon track data of Joint Typhoon Warning Center(JTWC)over the years,this paper studies the characteristics of warm-sector rainstorms in the middle and lower reaches of the Yangtze River.The results show that:(1)The warm-sector rainstorms occur 10.4 times a year on average in the middle and lower reaches of the Yangtze River,mostly in the period from June to August.The daily maximum precipitation at a single station is 53-226 mm,and the rainfall duration is shorter than 9 h.The precipitation amount from large to small is from the warm shear type,south wind convergence type and subtropical high edge type of rainstorms.(2)The diurnal variation characteristics of warm-sector rainstorm are obvious.The warm-shear-type rain-storm mostly starts in the early morning,and the probability of short-time heavy precipitation and extreme hourly rainfall intensity is the largest.The rainstorms of southerly convergence type and the subtropical high edge type mostly start after noon,and the latter usually lasts for no more than 3 h.(3)In terms of spatial distribution,the warm-sector rainstorms mainly occur in the area south of the Yangtze River,and a single station experiences no more than 5 times of rainstorms in the study period,and the rainstorm peak time arrives in June.The four rainstorm centers are located in western Hunan,the junction of Hu-nan and Jiangxi,northeastern Jiangxi,and the southern parts of Jiangsu and Anhui.(4)The main main-tenance mechanism of the warm-shear warm-sector rainstorm is that the low-level jet transports water va-por and unstable energy to the convergence zone of shear lines.The coupling of the high-level and low-level jets strengthens the convective instability of the atmosphere.Triggered by the boundary layer or the ground convergence line,heavy precipitation occurs.The rainstorm of southerly wind convergence type occurs when the convergence of the low-level southerly wind causes water vapor to accumulate in the rain-storm area,and the intrusion of dry-cold air in the middle layer cooperates with the terrain effect and the ground meso-scale convergence line,triggering the occurrence of severe rainfalls.The rainstorm of sub-tropical high edge type is mainly caused by the release of unstable energy that comes from the afternoon thermal convection.This kind of rainstorms mostly occurs in southern Anhui and the Dabie Mountains.
Keywords：warm-sector rainstormthe middle and lower reaches of Yangtze Riverwarm-shear rainstormrainstorm of southerly wind convergence typerainstorm of subtropical high edge type
Publication Date：2025-09-30
Online Publishing Date：2026-09-12(First online date of this platform, not the publication date of the document)
Pages：11( 31-41 )