  We report on numerical and theoretical investigation of subauroral arcs
within strong subauroral ion drifts (SAID)--STEVE and Picket Fence. Their
explanation requires the specific suprathermal electron distribution and
excitation of vibrational and electronic states of neutral species. We show
that the ionospheric feedback in the strong SAID with low-density troughs with
or without a so-called ionospheric valley generates intense, small-scale
field-aligned currents and electric fields below the F2 peak. With these
fields, we solved the Boltzmann kinetic equation for the distribution of
electrons and power for excitation and ionization of neutral gas (the energy
balance). The obtained suprathermal electron population and energy balance are
just what is necessary for Picket Fence. Concerning STEVE, the kinetic theory
predictions are in a good qualitative agreement with its basic features.
Besides, the theory predicts that subauroral arcs might have the transient
phase with typical aurora-like emissions that fade out afterwards.
