Analysis of Mesoscale Characteristics and Causes of A Short-term Heavy Rainfall in Southern Jiangxi
On June 12,2022,a heavy precipitation process in the southern part of Jiangxi was not reported in the operational work due to the weak convective activity.This paper analyzes the circula-tion background during the precipitation,the mesoscale characteristics,radar echoes and the causes of precipitation around 20:00 pm on June 12.The results show that this heavy precipitation occurred in front of the low trough at 500 hPa,south of the low-level shear line,and the front end of the jet stream.During the heavy precipitation,the subtropical jet stream center exhibited a fluctuating pat-tern,with strong high-altitude divergence and coupling suction effects between high and low levels,resulting in stronger precipitation.Despite weak convective conditions indicated by environmental parameters in northern Jiangxi during the short-term heavy precipitation process,intense water vapor convergence and strong upward motion were brought about by the suction effect of high-altitude di-vergence and low-altitude convergence,combined with the influence of terrain,resulting in signifi-cant short-term heavy precipitation.The timing and location of short-term heavy precipitation matched well with the location of strong radar echoes.The evolution of radar echoes corresponded well with the evolution of precipitation.When the rainfall was heavy,the echo intensity above 45 dBZ extended to a height of over 5 km,and the differential reflectivity(ZDR)was≥1.5 dB.Moreover,the occurrence time of radar echoes preceded the changes in rainfall intensity during short-term heavy precipitation,with reflectivity leading by approximately 18～24 minutes and KDP lead-ing by a slightly shorter time but showing a more consistent relationship with precipitation changes.
short-time heavy rainfallmesoscale characteristicstopographic effectcause analysis
万方数据
维普
