1.2 Numerical simulation of three-dimensional vortical interactions within an idealized tornado

Monday, 5 November 2012: 12:00 AM
Symphony I and II (Loews Vanderbilt Hotel)
Gregory J. Tripoli, University of Wisconsin, Madison, WI; and M. L. Büker

A fine scale simulation of the interaction between turbulent eddies and a supercell mesocyclone vortex leading to the formation of a top-down tornado are presented. Several distinct types of vortical interactions are described including: (1) middle level miso-vortex formation within the mesocyclone resulting from the thermodynamical and dynamical interaction with a penetrating RFD vortex loop, (2) the downward extension of the outer miso-cyclone and attached vortex loop, forming a deep arched structure, spanning the depth of the troposphere (3) dynamic entrainment of surface based frictionally induced horizontal vorticity into the miso-cyclone, (4) interaction between cyclonic and anticyclonic miso-vortices across the vortex arch , (5) Wrapping of filaments from the anticyclonic miso-cyclone around the primary vortex, creating regions of “superhelicity” that incrementally add to the strength of the primary vortex, (6) transformation of the binary arched vortex structure to a toroidal vortex structure via the mergers. Diagnostic calculations are performed to unveil the dynamic mechanisms driving these interactions.
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