大气科学2025，Vol.49Issue(6)：1727-1745,19.DOI:10.3878/j.issn.1006-9895.2407.24015
一次甘肃省东部强降水过程中多个中尺度对流系统的对比
Comparison of Multiple Mesoscale Convective Systems during a Heavy Rainfall in Eastern Gansu Province
摘要
Abstract
Based on multisource observational data and ERA5 reanalysis data,the differences of mesoscale convective systems(MCSs)were analyzed during heavy rainfall in eastern Gansu Province from 15 to 16 July 2022.The results show that:(1)This process was successively caused by the quasi-stationary MCS-A affecting from southern Ningxia to northern Shaanxi,MCS-B affecting most of southeast Gansu,MCS-C developing locally in eastern Longdong,Gansu,and broken line MCS-D forming in western Shaanxi,resulting in four rainbands.(2)MCS-A occurred during the precipitation stage[0000-1200 BJT(Beijing time)15 July]in the warm region;its rainband 1 had a small range,considerable cumulative rainfall,strong convection,and stable changes,with extreme heavy rain occurring locally,making it the strongest process.The other three MCSs occurred in the baroclinic frontal precipitation stage(1300 BJT 15 July to 0200 BJT 16 July).Rainbands 2,3,and 4 occurred in the stages of MCS-B triggering,MCS-B merging with MCS-C to form a squall line,and the squall line fracture merging with MCS-D and strengthening again,respectively.Rainbands 3 and 4 exhibited higher precipitation intensity,whereas rainband 2 was weaker.(3)The cloud top structure of MCS-A is characterized by a quasi-oval cloud developed in isolation,with a back-building convection structure at the middle and lower levels,indicating a significant train effect.The cloud top structure reflects a banded mesoscale sustained stretching-type convective system formed from MCS-B,MCS-C,and MCS-D,with their mesoscale and lower convective structures showing a trailing stratiform pattern.(4)During the development of MCS-A,two persistent ground-based cold pools interacted.The initiation of MCS-A is linked to the outflow boundary from the downstream cold pool 2,as well as the convergence,mesoscale frontogenesis,and subtle temperature and humidity perturbations induced by the blocking effect of upstream cold pool 1.Subsequently,this system is sustained over an extended period through a phase equilibrium between the cold pool and lower-level vertical wind shear,fluctuations in low-level jet stream wind velocity,and the mutual cancellation of advection and propagation.(5)MCS-B was initiated by a 700-hPa shear line.Subsequently,as various types of surface convergence lines merged into a"three point"amidst intensified temperature and moisture disturbances,MCS-C and MCS-D were successively triggered.Their sustenance can be attributed to recurrent mergers,strong water vapor transport at mid-to-low levels,and the generation of cold air at mid-to-upper levels.关键词
中尺度对流系统/极端特大暴雨/冷池/垂直风切变/低空急流Key words
Meso-scale convective system/Extremely heavy rainstorm/Cold pool/Vertical wind shear/Low level jet分类
天文与地球科学引用本文复制引用
杨丽杰,刘维成,刘新雨,嵇康,谭丹..一次甘肃省东部强降水过程中多个中尺度对流系统的对比[J].大气科学,2025,49(6):1727-1745,19.基金项目
甘肃省青年科技基金项目23JRRM0750,国家自然科学基金项目42575011,中国气象局气象能力提升专项23NLTSZ001,甘肃省气象局气象科研项目Ms2023-08,甘肃省气象局人才计划项目2425rczx-B-QNYXRC-05 Youth Science and Technology Fund Project of Gansu Province(Grant 23JRRM0750),National Natural Science Foundation of China(Grant 42575011),Special Project for Improving Meteorological Capability of China Meteorological Administration(Grant 23NLTSZ001),Meteorological Research Project of Gansu Meteorological Bureau(Grant Ms2023-08),Meteorological Bureau Talent Plan Project of Gansu Province(Grant 2425rczx-B-QNYXRC-05) （Grant 23JRRM0750）
