On possible disturbances of large-scale electric fields in the middle and low latitude ionosphere during the 31 March 2001 magnetic superstorm that followed an intensive Sun flare

On the basis of ionospheric data involving the simplified model calculating the electric field of the magnetospheric sources we tried to estimate the basic behavior features of large-scale electric field in the inner plasmasphere during the 31 Mar 2001 magnetic superstorm caused by the powerful 29 Mar 2001 solar flare. We obtained that the most favorable conditions for penetration of the large-scale field of magnetospheric convection into the low and equatorial latitudes had emerged at the last stage of the storm's main phase development. In the night ionosphere of low and equatorial latitudes within approximately one hour the electric field zonal component was headed eastward and reached - 2 mV/m which led to a "trough" in the electron concentration in the ionosphere's F2-field upper part near the magnetic equator in which the electron concentration declined more than by two orders of magnitude compared with that of the background.