Dual-Polarization Radar Observations of the Evolution of a Supercell Tornado and Analysis of the Echo Mechanisms

To gain a deeper understanding of the structural and evolutionary characteristics supercell tornadoes that occurred in eastern China on 14 May 2021, observations from S-band dual-polarization radars, soundings other instruments are used to investigate process tornado formation by mergering strengthening storms. The results described as follows. updraft upper divergence vertical thermal instability induced cold source at tropopause provided environmental conditions suitable for formation. event involved three storm merger processes, each which was associated with an increase echo intensity, rising speed, vorticity supercell. Furthermore, during last merger, merging two vortices resulted reduction rotation radius new vortex, also favorable condition tornadogenesis. A schematic proposed describe mergers. velocity spectrum width were indicative occurrence evolution this case. During stage, distinct polarimetric variable signatures (e.g., debris signature differential reflectivity arc) radial (i.e., tornadic vortex signature) observed.