MAGNETOSPHERIC DISTURBANCES IMPACT ON THE IONOSPHERIC DAILY FOF2 FREQUENCIES

The polar cusp being a region of the free access of the solar wind into the inner magneto-sphere is also the site of turbulent plasma flow. The cusp area at low altitudes acts like a focus of a variety type of instability and disturbances from different regions of the Earth. Daily foF2 frequencies are discussed regarding the cusp position. The high time resolution wave measurements together with electron and ions energetic spectra measurements registered on the board of Freja satellite and Magion-3 and the electron density at the peak of foF2 layers collected from ground base ionosonde measurements were used to study the response of ionospheric plasma within cusp-cleft region to the strong geomagnetic storm. In this paper we present the response of the ionospheric plasma to the disturbed conditions seen in the topside wave measurements and in the ionospheric characteristics maps obtained from the ground based VI network. The need of the cusp feature model for radio communication purposes is advocated.