Observation characteristics of dual-polarization radar for typical local microburst cases in Shanghai under weak synoptic forcing
ZHANG Jing
TAO Lan
GUAN Li
DAI Jianhua
ZHAO Yuanming
WANG Pengfei
Abstract：In order to analyze the evolution of microbursts in Shanghai under weak synoptic forcing and reveal the common characteristics of dual-polarization radar,this paper analyzes the evolutionary characteristics of 6 microburst storm cells in two local severe convection events in Shanghai under weak synoptic-scale background on 6 and 12 August 2022,using S-band dual-polarization Doppler weather radar data,conventional observations and other relevant datasets.The results are as follows.(1)Thermodynamic environments and triggering conditions.Both events are under the control of the subtropical high and characterized by high instability and weak vertical wind shear,with boundary layer convergence lines(e.g.,sea breeze fronts,horizontal convective rolls,thunderstorm outflow and their interactions)as the primary triggering mechanisms for thunderstorms.Pulse storms merge and strengthen,or develop rapidly under the collision of early thunderstorm outflows,resulting in short-term heavy precipitation and microburst.(2)Dominant physical mechanisms of microbursts.During the two events,the average wind speed in the entrainment layer is relatively low,leading to a weak momentum downward transport mechanism;the primary physcial mechanism for microburst formation is the phase-change cooling(evaporation,melting,etc.)of hydrometeor particles and precipitation drag.(3)Dual-polarization radar precursors.The KDP core near the melting layer(wet bulb temperature zero)and 1 km below it can directly indicate the melting and descent of ice-phase particles within the melting layer,generating negative buoyancy.The increase in the peak KDP core can foreshadow an impending downdraft burst within the next 12-6 min.(4)Other dual-polarization radar precursors.The descending of ZH core and KDP core,which both indicate the fall of ice-phase precipitation particles,the weakening and descending of ZDR column near the melting layer,which reflects strong updrafts,and the ZDR trough observed during the process with large hailstones etc.,can all be used as precursors of microbursts.
Keywords：weak synoptic forcingmicroburstZH coreZDR columnKDP core
Publication Date：2025-12-30
Online Publishing Date：2026-05-22(First online date of this platform, not the publication date of the document)
Pages：15( 1-15 )