THEORY OF NIGHT-TIME F-LAYER

The behaviour of the night-time F-layer, as it appears from the quantities hm, Ym and Nm (height of the F-layer maximum, layer thickness and maximum electron concentration), can be interpreted by electron losses, ambipolar diffusion and plasma drifts caused by electric fields in W-E and in N-S direction. The electric fields must be of the order of 5-10 V/km, if the loss coefficient and the ambipolar diffusion constant are chosen in accordance with laboratory measurements of the reaction rate for O+ + N2 → NO+ + N and of the diffusion cross section for O+ in O. The theoretical method which gives these results proceeds from the time-dependent continuity equation and the appropriate equations of motion for the electrons, ions and neutral particles which form a system of coupled partial differential equations. This system is solved numerically by means of an electronic computer. © 1968.