Tuesday, 29 August 2023: 2:00 PM
Great Lakes BC (Hyatt Regency Minneapolis)
Previous studies have identified the importance of storm-generated baroclinic boundaries in the production of low-level vertical vorticity in supercell thunderstorms. Parcels inbound to the low-level mesocyclone have been shown to traverse through these baroclinic regions in the left and forward flanks and acquire solenoidally generated horizontal vorticity, which can be subsequently tilted and stretched by the updraft. Recent very high-resolution numerical simulations (with horizontal grid spacing of 125 m or less) have suggested that very intense realizations of this horizontal vorticity may exist near the surface, directly modulate low-level mesocyclone intensity, and possibly influence the genesis of tornado-like vortices.
The Targeted Observations by Radars and Unmanned Aircraft Systems of Supercells (TORUS) Project took place during the spring seasons of 2019 and 2022, focused on observations of the kinematic and thermodynamic structure of boundaries generated by supercell thunderstorms. As part of this effort, two Texas Tech Ka-band radars were brought to the field, tasked with PPI and RHI interrogation of lead boundaries in supercells that were targeted. Over the span of the two seasons, thousands of individual RHIs were obtained over the flanks of target storms, allowing a longitudinal investigation of the kinematic character of this collection of outflows.
This presentation will include a description of the Texas Tech Ka-band radar operations during TORUS and results from this longitudinal investigation of nearly 1000 outflow samples, including all 2019 and 2022 cases. This catalog reveals the spectrum of kinematic presentations possible, from very broad confluence to robust density currents, a few of which feature inferred horizontal vorticity that is continuous in the along-boundary direction, and intensifying along that extent, consistent with the SVC structure that has been demonstrated in numerical studies. The catalog of outflows will be subsetted different ways, according to absolute value of (and changes in) the lowest level radar-inferred vertical vorticity (as measured by both operational and research assets), thereby gaining understanding of the downstream effects of these boundaries on low-level mesocyclone intensity.
The Targeted Observations by Radars and Unmanned Aircraft Systems of Supercells (TORUS) Project took place during the spring seasons of 2019 and 2022, focused on observations of the kinematic and thermodynamic structure of boundaries generated by supercell thunderstorms. As part of this effort, two Texas Tech Ka-band radars were brought to the field, tasked with PPI and RHI interrogation of lead boundaries in supercells that were targeted. Over the span of the two seasons, thousands of individual RHIs were obtained over the flanks of target storms, allowing a longitudinal investigation of the kinematic character of this collection of outflows.
This presentation will include a description of the Texas Tech Ka-band radar operations during TORUS and results from this longitudinal investigation of nearly 1000 outflow samples, including all 2019 and 2022 cases. This catalog reveals the spectrum of kinematic presentations possible, from very broad confluence to robust density currents, a few of which feature inferred horizontal vorticity that is continuous in the along-boundary direction, and intensifying along that extent, consistent with the SVC structure that has been demonstrated in numerical studies. The catalog of outflows will be subsetted different ways, according to absolute value of (and changes in) the lowest level radar-inferred vertical vorticity (as measured by both operational and research assets), thereby gaining understanding of the downstream effects of these boundaries on low-level mesocyclone intensity.
- Indicates paper has been withdrawn from meeting
- Indicates an Award Winner