Collaborative Research: Polarimetric Tornado Precursor Signatures

Purdue University, West Lafayette IN

Investigators

Abstract

Tornadoes are a significant hazard in the United States and while tornado warning times have lengthened over the past few decades, there is still room for improvement. One of the recent technological advancements in tornado science is the use of dual-polarimetric radar data. Dual-polarimetric radars transmit signals horizontally and vertically. Through the combination of those signals, we can infer properties of rain, snow and hail, such as their size and shape. It has been observed that there are specific polarimetric signals that show up prior to some tornado events. This research award will investigate those signals to determine why they form and whether they are good candidates to be used as indicators for developing tornadoes. The societal impact of the project is related to improving tornado warning times and increasing public safety. The research team is also working with an author to develop a non-fiction book about tornado scientists, targeted at 8 to 11-year-olds, to enhance scientific literacy. The goal of this project is to develop conceptual models of recurring differential reflectivity signatures in supercells with potential prognostic value for tornadogenesis. The research team will analyze existing rapid-scanning dual-polarized radar observations in supercells, collect new observations using a novel rapid-scanning dual-polarized mobile radar system, and utilize both sets of observations to develop and refine conceptual models of these differential reflectivity (Zdr) signatures in relation to tornadogenesis. The researchers will systematically focus on the Zdr column and Zdr arc behavior immediately prior to tornadogenesis, comprehensively documenting and analyzing a sample of 8-10 supercells. At least five additional tornadic supercells will be sampled using the UMass-Amherst phase-tilt weather radar (PTWR) during field studies during the award.