Convective Amplification of Irregularities in the Counter Equatorial Electrojet and Explanations of Some Observed Properties

The wave propagation and refraction of type "O" irregularities in the counter-electrojet conditions is investigated with a model electrojet in terms of the linear theory of the electrojet instability. Waves propagating with the electrons rotate their wave vectors downwards in the upper electrojet and upward in the lower electrojet. The ray-path integrated growth is much smaller than that in electrojet conditions for the same values of driven electric field |E_D| because the vertical component of group velocity is downward during the day and the electron density gradient is stabilizing. For the electron density characteristic length L_N = 6km and |E_D| = 0.8 mV/m, the integrated growth for wave length λ= 10m is less than 20 for altitudes h≥ 105 km. In these altitude range, waves may be not saturated. With increasing L_N, the value of |E_D| for waves still being linear at altitudes h ≥ 105 km decreases. The characteristics of the convective amplification mentioned above may be associated with some of the properties of the irregularities in the counter equatorial electrojet observed at Addis-Ababa in 1977 (reference
[6] ).