Lightning electromagnetic pulse penetration into the night-time lower ionosphere and plasma modification are simulated using the large particle method. The collisions of the electrons with the neutral species, both elastic and related to the excitation, ionization of and attachment to the neutrals are modeled using a Monte--Carlo technique. The dynamics of the impulse electron heating and breakdown in the lower ionosphere above the strong lightning discharge are analyzed. The level of the induced ionization strongly depends on the amplitude, form and duration of the incident pulses. The selfconsistent fields on the time scale of 102 &mgr;s are subjected to strongly nonlinear damping during the passage through the D-region of the ionosphere. ¿ American Geophysical Union 1996