AGS-PRF: A Unified Conceptual Model for the Development of Near-Surface Rotation in Squall Lines

Brown, Matthew C, Norman OK

Investigators

Abstract

Lines of thunderstorms, sometimes referred to as squall lines, are common occurrences in the United States and are accompanied by heavy rain, high winds, and occasionally tornadoes. Determining which squall lines are likely to contain tornadoes is a difficult forecast problem, even after a squall line has already formed. This Postdoctoral Research Fellowship award will investigate the role of low-level winds in the formation of the circulations in squall lines that lead to tornadoes. The main societal impact of the project is the potential of improved forecasting and nowcasting of tornadic events. The project also contributes to an early-career researcher’s career development. The development of rotation within squall lines, otherwise referred to as Quasi-Linear Convective Systems (QLCSs), is a complex physical problem. Many theories have been put forth to describe how the genesis of rotation in QLCSs begins, but the scientific community has not consolidated around any singular mechanism. The research under this award will use idealized numerical simulations, analysis of field campaign measurements, and a synthesis of recent advances on this topic to answer three critical research questions: 1) How do variations in the low level near-storm wind profile influence the ways in which squall lines produce intense, long-lived rotation close to the surface, 2) How do variations in Convective Available Potential Energy (CAPE) modulate the mesovortexgenesis process across the low-level shear spectrum, and 3) How does this near-storm environmental evolution impact the maintenance and rotation of QLCSs, and does the relative importance of vortexgenesis mechanisms evolve in time? This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.