Nonlinear structuring and southward shift of a strongly heated region in ionospheric modification

The theory of self-focusing on striations for the powerful radio wave beam propagating in the northern or midlatitude ionosphere is developed. It is d emonstrated that focusing lead to formation of a large scale nonlinear stru cture aligned magnetic field. It consists of a number of closely packed sol itons - bunches of striations. The anomalous absorption of a pump wave trap ped in solitons lead to the strong ohmic heating of electrons in the focuse d region. The theory is in a good agreement with the results of recent obse rvations of optic emission and temperature enhancement in northern ionosphe ric modification experiments. (C) 2001 Published by Elsevier Science B.V.