Open AccessA Possible Mechanism of Tornadogenesis Associated with the Interaction between a Supercell and an Outflow Boundary without Horizontal Shear
Author(s) -
Tomohiro Honda,
Tetsuya Kawano
Publication year - 2016
Publication title -
journal of the atmospheric sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.853
H-Index - 173
eISSN - 1520-0469
pISSN - 0022-4928
DOI - 10.1175/jas-d-14-0347.1
Subject(s) - outflow , tornado , supercell , mechanics , geology , boundary (topology) , buoyancy , vortex , drag , meteorology , physics , mathematics , mathematical analysis
Using the insert–restart method developed in this study, tornadogenesis processes associated with the interaction between a supercell and an outflow boundary were investigated. A highly idealized outflow boundary promoted surface vortex intensification in a preconditioned supercell having a strong surface vortex. In particular, a tornado-like vortex was observed in an experiment with a moderate outflow boundary. This intensification was associated with the enhancement of the near-surface horizontal convergence by the outflow boundary. The optimal coldness of the outflow boundary was explained by the balance between the enhancement of the near-surface horizontal convergence and the buoyancy reduction by the outflow boundary. Sensitivity experiments demonstrated that, despite a less favorable environment, a storm with a boundary interaction might reach a similar maximum near-surface vorticity as a storm without a boundary in a more favorable environment.