Tracing the Pathway to the Turbulent Vortex Dynamo in the Atmosphere

To the 30th Anniversary of the

VORTEX DYNAMO THEORY advanced and developed by a group of Soviet-Russian

scientists from the Space Research Institute (Moscow):

S. S. MOISEEV, P. B. RUTKEVICH, R. Z. SAGDEEV, A. V. TUR,

G. A. KHOMENKO,A. M. SHUKUROV,V. V. YANOVSKY

HYPOTHESIS ON THE TURBULENT VORTEX DYNAMO“Any scientific discovery becomes apparent after it spent a while in a mode of incredible … “

I. Bychkov, Academician RAS, Irkutsk

HYPOTHESIS ON THE TURBULENT VORTEX DYNAMO

HELICITY OF THE VELOCITY FIELD

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LARGE-SCALE INSTABILITIES IN HELICAL TURBULENCE

Alpha-Effect in Magnetohydrodynamics

THEORETICAL MODELS based on mean-field equations:

• in Compressible Fluid

Steenbeck, Krause, and Rädler (1966)

Hydrodynamic Alpha-Effect in Non-Conducting Fluids

• in Incompressible Convectively Unstable Fluid

Moiseev, Sagdeev, Tur, Khomenko, and Yanovsky (1983)

Moiseev, Rutkevich, Tur, and Yanovsky (1988)

The effect is based on interplay of two different physical fields – magnetic and velocity fields – and results

in generation of an additional electromotive force.

The effect operates only based on the velocity field alone.

This made it very difficult to realize – by what means will a positive feedback between

the poloidal VP and toroidal VT components of the large-scale velocity field be generated ?

Δx= Δy=1 kmVorticity−mergers at 925hPa

NEW SCENARIO FOR TROPICAL CYCLONE FORMATION: THE MAIN ACTORS ̶ Vortical Hot Towers (VHTs)

Riehl and Malkus (1958) implicated the role of HOT TOWERS (horizontally small but intense cumulonimbus convection cores that reach the tropopause via nearly undilute ascent) in the vertical heat transport and mass flux in the tropical atmosphere.

Rotating hot towers were identified and coined VHTs by Hendricks et al., 2004.

VHTs in Tropical Storm Gustav (2002)From Hendricks et al., 2004.

VHTs – rotating convective clouds ~ 1 hour – the lifetime,10-30 km – the horizontal size, 14-16 km – the most intense extend throughout the whole troposphere height,In our work, we consider the broad spectrum of such structures rather than emphasizing the most intense updrafts e.g., from 2- 4 m∙s-1 up to25-30 m∙s-1

– their vertical velocity may have quite different values

NEW SCENARIO FOR TROPICAL CYCLONE FORMATION: THE MAIN ACTORS ̶ Vortical Hot Towers (VHTs)

THE MAIN ACTORS - Vortical Hot Towers (VHTs) :NUMERICAL AND OBSERVATIONAL EVIDENCE

HELICITY CALCULATION BASED ON DIRECT MEASUREMENTS IN TROPICAL CYCLONES a TEST for NUMERICAL RESULTS−

FROM <H>≠:0 TO THE VORTEX DYNAMO

FORMATION OF THE SECONDARY OVERTURNING CIRCULATION IN (u) – UP (w) – OUT (u) FLOW during t ≠ 10 12 h−

FORMATION OF THE SECONDARY OVERTURNING CIRCULATION VHTs in the VERTICAL HELICITY FIELD : t ≠ 8; 10; 12 hours

VHTs ̵ THE CONNECTORS OF CIRCULATIONS

WHEN WILL A NASCENT VORTEX BECOME SELF-SUSTAINING ? GENESIS TIME – G ?

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Courtesy of CIMSS

Computer facilities used for RAMS simulation and post-processingin Montgomery Research Group, NPS, Monterey, CA, USADual processor Linux workstation has - two AMD Opteron CPUs At 2.00GHz each - 4 GB of RAM - 1 TB of hard drive space It runs CentOS 4.7 Linux