Lastly, the setting of the superposition of IGWs and the
vertical electric field affects the variations of neutral atmosphere composition just as the IGWs itself, and the variations of the meridional electric field just as the vertical
electric field itself. Note that the effects in meridional thermospheric wind and in zonal electric field are larger than
the total effect of each of these mechanisms taken separately. The positive disturbance in TEC in this case is
formed by the zonal electric field and by the growth of the
ratio n(O)/n(N2), and—in pre-sunrise hours—is supported
by an additional equatorward wind. An additional poleward
wind in the afternoon prevents the growth of TEC, and—in
the vicinity of the evening terminator—the meridional electric field prevents any significant growth of TEC