1. A Comparison of Mobile Radar-Inferred Rain-Drop Size Estimates between Tornadic and Non-Tornadic Supercell Hook Echoes
- Author
-
Foster, James A.
- Subjects
- Geography, Meteorology, Tornadogenesis, precipitation properties, meteorology, tornado, hook echo, differential reflectivity
- Abstract
Radar observations obtained from The University of Oklahoma’s mobile X-band Polarimetric radar (RaXPol) are used to investigate and compare qualitative precipitation sizes (e.g. small vs. large) and distribution within the hook echoes of two supercell storms to explore if various precipitation sizes preclude tornadogenesis or are related to tornadogenesis failure. The tornadic case occurred near El Reno, Oklahoma on 31 May 2013, and the non-tornadic one occurred in southwestern Oklahoma on 23 May 2011. This study extends previous work investigating this topic by improving the temporal resolution of data, incorporating rapid-scan observations available every 30-45 seconds. A distinctive polarimetric signature, small drops (low ZDR) to the south and east of the rotation in tornadic hook echoes, is investigated further. It is thought that small drops reduce ZDR and is seen in many tornadic hook echoes investigated by previous research. Qualitative differences in precipitation size within the tornadic and non-tornadic hook echoes are investigated by exploring the changes in reflectivity (Z) and differential reflectivity (ZDR) within the whole hook echo and within the quadrants to the northwest, northeast, southwest, and southeast of the center of rotation. Comparisons are made between the Z-ZDR relationships found in prior research and the results herein to examine differences between the observed hook echoes and what is considered “normal” Oklahoma precipitation. The tornadic hook echo displayed a distinct area of small drops to the south and east of the rotation at the time of tornadogenesis. The non-tornadic hook echo also displayed smaller drops around tornadogenesis failure, but the drops were larger overall than the tornadic case. For the most part, drop sizes in both hook echoes were larger than the Cao et al. previous research observed, but the southeast quadrants of both hook echoes exhibited smaller drops than other quadrants. The overall mean change in ZDR in the hook echoes was minimal. However, the changes in the quadrants changed quite drastically alluding to differing microphysics in each quadrant.
- Published
- 2020