The mechanisms responsible for large near-surface vertical vorticity within simulated supercells and quasi-linear storms

Christian H. Boyer, Johannes M.L. Dahl

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Despite their structural differences, supercells and quasi-linear convective systems (QLCS) are both capable of producing severe weather, including tornadoes. Previous research has highlighted multiple potential mechanisms by which horizontal vorticity may be reoriented into the vertical at low levels, but it is not clear in which situation what mechanism dominates. In this study, we use the CM1 model to simulate three different storm modes, each of which developed relatively large near-surface vertical vorticity. Using forward-integrated parcel trajectories, we analyze vorticity budgets and demonstrate that there seems to be a common mechanism for maintaining the near-surface vortices across storm structures. The parcels do not acquire vertical vorticity until they reach the base of the vortices. The vertical vorticity results from vigorous upward tilting of horizontal vorticity and simultaneous vertical stretching. While the parcels analyzed in our simulations do have a history of descent, they do not acquire appreciable vertical vorticity during their descent. Rather, during the analysis period relatively large horizontal vorticity develops as a result of horizontal stretching, and therefore this vorticity can be effectively tilted into the vertical.

Original languageEnglish
Pages (from-to)4281-4297
Number of pages17
JournalMonthly Weather Review
Volume148
Issue number10
DOIs
StatePublished - Oct 2020

Keywords

  • Cloud resolving models
  • Numerical analysis/modeling
  • Squall lines
  • Supercells
  • Tornadogenesis
  • Trajectories

Fingerprint

Dive into the research topics of 'The mechanisms responsible for large near-surface vertical vorticity within simulated supercells and quasi-linear storms'. Together they form a unique fingerprint.

Cite this