Generation of internal gravity vortices in the high-latitude ionosphere

It is shown that ionosphere heating by DC electric field leads to instability of acoustic-gravity waves and to the formation of solitary internal gravity vortex structures. These dipole type vortices with characteristic transverse size of the order of several kilometers are propagated in the lower ionosphere with subsonic velocity. The threshold values of the electric field needed to suppress the wave damping caused by the interaction of induced current with the geomagnetic field and to provide the vortex generation are found. The considered physical mechanism is applicable to the generation of internal gravity vortices and related ionospheric disturbances when the ionosphere is influenced by the electric field of seismic origin exceeding the threshold value. (C) 2010 Elsevier Ltd. All rights reserved.