Kinematics and Microphysical Characteristics of the First Intense Rainfall Convective Storm Observed by Jiangsu Polarimetric Radar Network

摘要

The polarimetric radar network in Jiangsu Province has just been operationalized since 2020.The first intense precipitation event observed by this polarimetric radar network and disdrometer occurred during August 28-29,2020 and caused severe flooding and serious damage in eastern Jiangsu Province.The microphysics and kinetics for this heavy precipitation convective storm is diagnosed in this study,in order to promote the application of this polarimetric radar network.Drop size distribution(DSD)of this event is estimated from measurements of a ground disdrometer,and the corresponding three-dimensional atmospheric microphysical features are obtained from the multiple polarimetric radars.According to features of updraft and lighting,the evolution of the convective storm is divided into four stages:developing,mature with lightning,mature without lightning and dissipating.The DSD of this event is featured by a large number of raindrops and a considerable number of large raindrops.The microphysical characteristics are similar to those of warm-rain process,and ice-phase microphysical processes are active in the mature stages.The composite vertical structure of the convective storm indicates that deep ZDR and KDP columns coincide with strong updrafts during both mature stages.The hierarchical microphysical structure retrieved by the Hydrometeor Identification Algorithm(HID)shows that depositional growth has occurred above the melting level,and aggregation is the most widespread ice-phase process at the-10℃level or higher.During negative lightning activity,the presence of strongest updrafts and a large amount of ice-phase graupel by riming between the 0℃and-35℃layers generate strong negative electric fields within the cloud.These convective storms are typical warm clouds with very high precipitation efficiency,which cause high concentration of raindrops,especially the presence of large raindrops within a short period of time.The ice-phase microphysical processes above the melting layer also play an important role in the triggering and enhancing of precipitation.