Earth Planets Space, Vol. 61 (No. 5), pp. 643-648, 2009LETTER
L. A. Leonovich and A. V. Taschilin
Institute of Solar-Terrestrial Physics, Russian Academy of Sciences SB RAS, 664033 p/o box 4026, Irkutsk, Russia
(Received October 23, 2007; Revised February 22, 2008; Accepted March 20, 2008; Online published May 29, 2009)
We obtained that according to the GPS data at altitudes of the topside ionosphere (h > 300 km) a flare is able to cause a decrease of the electron content. Using the theoretical model it is shown that the intense transport of O+ ions into the above-situated plasma caused by a sharp increase in the ion production rate and thermal expansion of the ionospheric plasma is a cause of the formation of the negative disturbance in the electron concentration in the topside ionosphere.
Key words: Solar flares, disturbances, ionosphere, GPS, modeling.