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Wave Driven Non-Linear Flow Oscillator for the 22-Year Solar CycleWe propose that waves generate an oscillation in the Sun to account for the 22-year magnetic cycle. The mechanism we envision is analogous to that driving the Quasi Biennial Oscillation (QBO) observed in the terrestrial atmosphere, which is well understood in principal. Planetary waves and gravity waves deposit momentum in the background atmosphere and accelerate the flow under viscous dissipation. Analysis shows that such a momentum source represents a non-linearity of third or generally odd order, which generates also the fundamental frequency/period so that an oscillation is maintained without external time dependent forcing. For the Sun, we propose that the wave driven oscillation would occur just below the convection region, where the buoyancy frequency or convective stability becomes small to favor wave breaking and wave mean flow interaction. Using scale analysis to extrapolate from terrestrial to solar conditions, we present results from a simplified analytical model, applied to the equator, that incorporates Hines'Doppler Spread Parameterization for gravity waves (GW). Based on a parametric study, we conclude: (1) Depending on the adopted horizontal wavelengths of GW's, wave amplitudes < 10 m/s can be made to produce oscillating zonal winds of about 25 m/s that should be large enough to generate a corresponding oscillation in the main poloidal magnetic field; (2) The oscillation period can be made to be 22 years provided the buoyancy frequency (stability) is sufficiently small, which would place the oscillating wind field near the base of the convection region; (3) In this region, the turbulence associated with wave processes would be enhanced by low stability, and this also helps to produce the desired oscillation period and generate the dynamo currents that would produce the reversing magnetic field. We suggest that the above mechanism may also drive other long-period metronomes in planetary and stellar interiors.
Document ID
20010059956
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Mayr, H. G.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Wolff, C. L.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Hartle, R. E.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Einaudi, Franco
Date Acquired
August 20, 2013
Publication Date
January 1, 2000
Subject Category
Solar Physics
Meeting Information
Meeting: American Geophysical Union Fall Meeting
Location: San Francisco, CA
Country: United States
Start Date: December 15, 2000
End Date: December 19, 2000
Sponsors: American Geophysical Union
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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