Self-organization of large-scale ULF electromagnetic wave structures in their interaction with nonuniform zonal winds in the ionospheric E region

Journal Article · Tue Feb 15 04:00:00 EST 2011 · Plasma Physics Reports

DOI:https://doi.org/10.1134/S1063780X10111017· OSTI ID:22047552

Aburjania, G D ^[1]; Chargazia, Kh Z ^[2]

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1. Tbilisi State University, I. Vekua Institute of Applied Mathematics (Georgia)
2. Nodia Institute of Geophysics (Georgia)

A study is made of the generation and subsequent linear and nonlinear evolution of ultralow-frequency planetary electromagnetic waves in the E region of a dissipative ionosphere in the presence of a nonuniform zonal wind (a sheared flow). Hall currents flowing in the E region and such permanent global factors as the spatial nonuniformity of the geomagnetic field and of the normal component of the Earth's angular velocity give rise to fast and slow planetary-scale electromagnetic waves. The efficiency of the linear amplification of planetary electromagnetic waves in their interaction with a nonuniform zonal wind is analyzed. When there are sheared flows, the operators of linear problems are non-self-conjugate and the corresponding eigenfunctions are nonorthogonal, so the canonical modal approach is poorly suited for studying such motions and it is necessary to utilize the so-called nonmodal mathematical analysis. It is shown that, in the linear evolutionary stage, planetary electromagnetic waves efficiently extract energy from the sheared flow, thereby substantially increasing their amplitude and, accordingly, energy. The criterion for instability of a sheared flow in an ionospheric medium is derived. As the shear instability develops and the perturbation amplitude grows, a nonlinear self-localization mechanism comes into play and the process ends with the self-organization of nonlinear, highly localized, solitary vortex structures. The system thus acquires a new degree of freedom, thereby providing a new way for the perturbation to evolve in a medium with a sheared flow. Depending on the shape of the sheared flow velocity profile, nonlinear structures can be either purely monopole vortices or vortex streets against the background of the zonal wind. The accumulation of such vortices can lead to a strongly turbulent state in an ionospheric medium.

• OSTI ID: 22047552
• Journal Information: Plasma Physics Reports, Journal Name: Plasma Physics Reports Journal Issue: 2 Vol. 37; ISSN PPHREM; ISSN 1063-780X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANGULAR VELOCITY
DEGREES OF FREEDOM
DISTURBANCES
E REGION
EARTH PLANET
EIGENFUNCTIONS
ELECTRIC CURRENTS
ELECTROMAGNETIC RADIATION
GEOMAGNETIC FIELD
NONLINEAR PROBLEMS
PLASMA INSTABILITY
SHEAR
VORTICES