Dynamic processes in the ionosphere during magnetic storms from the Kharkov incoherent scatter radar observations

Ye. I. Grigorenko, V. N. Lysenko, and V. I. Taran
Institute of the Ionosphere, National Academy of Sciences of Ukraine, Ministry of Education and Science of Ukraine, Kharkov, Ukraine

Abstract

[1]  Results of studying the ionosphere behavior during several magnetic storms of various intensities are presented. The features of pronounced negative ionospheric disturbances accompanying the severe magnetic storms on 25 September 1998 and 29-30 May 2003 ( Kp 8) are considered. Among them there are a decrease in the electron density by a factor of 3-4, uplifting of the ionospheric F2 layer by 100-160 km, increase in the temperature of the charged and neutral atmospheric components, and infringement of plasma transfer processes and thermal balance in the ionosphere-plasmasphere system. In the morning of 25 September 1998, an unusual increase in the upward plasma drift velocity was registered. On 29-30 May 2003 during the storm main phase, a depletion of the relative density of hydrogen ions by more than an order of magnitude was observed that could manifest an emptying of the magnetic flux tube over Kharkov. These effects are explained in terms of thermospheric disturbances, Joule heating, particle precipitation, penetration of magnetospheric electric fields to midlatitudes, the shift of the main ionospheric trough and related structures toward the radar latitude, etc. The ionospheric storm on 20-21 March 2003 had two phases. Its strong negative phase proceeded against a background of a minor geomagnetic disturbance ( Kp 5). The destabilizing impact of the electric field pulse and traveling atmospheric disturbance generated by magnetospheric substorms could be the cause of the change in the storm phase that occurred in the sunset period.

Received 4 July 2005; revised 25 September 2006; accepted 6 July 2007; published 26 October 2007.

Keywords: ionosphere; magnetic storms; incoherent scatter radar observations.

Index Terms: 2431 Ionosphere: Ionosphere/magnetosphere interactions; 2788 Magnetospheric Physics: Magnetic storms and substorms; 6969 Radio Science: Remote sensing.