Refined Structural Evolution Analysis of a Tornado

GUAN Li; YIN Chunguang; ZHU Jiakai; ZHANG Lijuan

doi:10.16032/j.issn.1004-4965.2025.030

Abstract：The study conducts a comprehensive analysis of the tornado in Nantong on 10 June,2023,using data from Nanhui WSR-88D radar,Nantong CINRAD-SAD S-band dual-polarization radar,collaborative vertical observations from the CINRAD-XAD X-band dual-polarization radar,ERA5 reanalysis data,and conventional observational data.The results showed that:(1)The tornado took place under the background of a northeast cold vortex,with the overall configuration characterized by an upper-level forward-tilted trough,indicating a typical high-altitude cold advection-forced wind and hail weather system.Prior to the event,the energy accumulated and environmental indices were favorable for a tornado's formation.(2)During this event,Plan Position Indicator(PPI),which was at a 0.5 ° elevation angle from both the Nanhui and Nantong radars,revealed typical tornado characteristics such as hook echoes,mesocyclones,differential reflectivity(ZDR)arcs,and Tornadic Debris Signatures(TDS).Meanwhile,the gust fronts of forward flank downdrafts(FFD)and rear flank downdrafts(RFD)were recognized in combination with the regional automatic weather stations.(3)The CINRAD-XAD X-band dual-polarization radar's conducted continuous Range Height Indicator(RHI)scans for 20 minutes on the tornado parent storm,meticulously capturing features such as ZDR columns,storm top divergence,and hail zones.It also successfully documented multiple ground touches in this event.(4)By integrating the high-resolution observational data from both S-band radar PPI scan and the X-band RHI scan,the study develops vertical and horizontal conceptual models of tornado formation within the westerlies.It also illustrates the typical dual-polarization radar characteristics,making it clear to understand the formation mechanisms of such westerly belt tornadoes.