March 12, 2021 - 3:00 pm
March 12, 2021 - 4:00 pm
CategoriesConvective Meteorology (Mesoscale Dynamics)
Convective Meteorology (Mesoscale Dynamics) Seminar
Exploring Observational Tornado Debris Signature Hypotheses Using Radar Simulations and Large-Eddy Simulations
Friday, March 12th
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Tornadoes can loft various types and sizes of debris, sometimes resulting in a polarimetric radar signature called the TDS (Tornado Debris Signature). The presence of a TDS in the radar data can help confirm the occurrence of a tornado, and provide information about the amount of damage occurring, making it a useful feature for operational forecasters. Past observational studies have suggested how the TDS evolves during a tornado’s lifecycle, but few studies have related the polarimetric characteristics of a TDS to the tornado’s wind field owing to the difficulty in obtaining three-dimensional wind data in tornadoes. This study aims to not only investigate the relationships between polarimetric weather radar variables in TDSs and the three-dimensional winds of tornadoes, but to also breakdown the relationship of the TDS debris size, type, and concentration.
A simulation-based framework is adopted since the tornado debris and wind characteristics are known, and thus these relationships proposed from observations can be explored in a more controlled manner. To accomplish this, simulations were performed using Large-Eddy Simulations of tornadoes and a dual-polarization radar simulator called SimRadar. Using SimRadar and a single-volume emulator, relationships between polarimetric variables and debris size, type, and concentrations are analyzed. Specifically, our study evaluates if reflectivity and correlation coefficient can provide information about debris size and concentration. Additionally, a dynamic, tornadogenesis simulation is used to allow for the analysis of the evolution of polarimetric variables in an intensifying tornado. Results from these simulations show how wind characteristics of the simulated tornadoes, such as updraft intensity and area, magnitude of horizontal wind speeds, and vertical vorticity, are related to polarimetric variables. These findings can aid operational forecasters in tornado detection and potentially the categorization of damage severity using radar data.