Shawnee/ Moore, Oklahoma May 20, 2013.

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Presentation transcript:

Shawnee/ Moore, Oklahoma May 20, 2013

MPEX Mobile Soundings 19 May 2013 CSU 19 UTC CSU 21 UTC CSU 23 UTC WRF OUN 19 UTC WRF OUN 23 UTC WRF OUN 00 UTC

Trier et al. MWR 2015 Ensemble-analyzed circulation along dry line: 19 May 2013

Supercells

MICRO- PHYSICS

Physical processes controlling cell types: Buoyancy processes: basic updraft/downdraft, (ordinary cells) Gust front processes: triggering of new cells, upscale growth, (multicells) Dynamic processes: rotating updraft, dynamic vertical pressure gradient forcing, (supercells)

Physical processes controlling cell types: Buoyancy processes: basic updraft/downdraft, (ordinary cells) Gust front processes: triggering of new cells, upscale growth, (multicells) Dynamic processes: rotating updraft, dynamic vertical pressure gradient forcing, (supercells)

Momentum Eq. Dynamic Pressure Eq. --

Linearise pressure eq. about U(z), V(z) (environmental vertical wind shear) So, since

2D Updraft in Sheared Environment:

Vorticity Equation: Vertical Vorticity: tilting stretching

Vortex Tube Circulation:

Theorems for inviscid fluids with conservative external forces (e. g Theorems for inviscid fluids with conservative external forces (e.g., no baroclinicity, buoyancy) (Helmholtz, 1858) ….Vortex lines (tubes) are material lines that are frozen into the fluid. ….The circulation (strength) of a vortex tube is invariant …The circulation on any curve around a vortex tube is constant along the tube.

Tilting: Linearized about a mean vertical wind shear:

Vertical Momentum Eq. (rewritten) (dynamic) + (buoyancy)

(H = horizontal shearing deformation) So, for a wind profile in pure rotation: So, again, since

Supercell Hodographs: Supercell processes are Galilean invariant!!!

Linearise pressure eq. about U(z), V(z) (environmental vertical wind shear) So, since

Bunkers et al. WAF 2000

Weisman and Rotunno, Jas 2000