Entropic Balance Theory and Radar Observation for Prospective Tornado Data Assimilation - Data Assimilation for Atmospheric, Oceanic and Hydrologic Applications - page 435

Fig. 18.9 Wrap-around
mechanism. Schematic
illustration of nonlinear
process transforming the
baroclinic state ( top )to
barotropic state with
baroclinic core ( bottom )

18.7 Wrap-Around Mechanism

It was suggested in the earlier publications ( Sasaki 2009 , 2010 ) that the mature stage
of tornado appears almost discontinuously from the parent supercell, like the axially
symmetric, nonlinear attractor, and a singular stationary-state vortex, by the pro-
posed process named the “wrap-around mechanism.” The wrap-around mechanism
is analogous to the baker's transformation in nonlinear dynamics although it is two
dimensional while the baker's transformation is one dimensional. The wrap-around
mechanism becomes activated by the mesocyclone existing between the entropic
source and sink, which is a baroclinic state, and is expected from the entropic right-
hand rule (Fig. 18.1 ). The mesocyclone produces a circular belt of entropic source
around the sink. The circular system is an ensemble of specific combinations of the
original vorticity and its conjugate (Figs. 18.5 and 18.6 ). The conjugate vorticity has
a conjugate entropy gradient and conjugate flow velocity (rotational component),
but with an integrated magnitude of vorticity and direction. Thus, the original vortex
and conjugate vortex produce the integrated magnitude of vorticity in the original
direction.