Theoretical properties of two-dimensional electrojet turbulence

Turbulence in the equatorial electrojet is attributed to the nonlinear evolution of the gradient drift instability. Solutions are given for a set of nonlinear coupled differential equations for the amplitudes of a two-dimensional Fourier series representing the density fluctuations. The differential equations are derived from the electrons by retaining the divergence of electron flux as the only nonlinearity. The results pertain to daytime conditions when dissociative recombination is the dominant linear wave damping mechanism. The irregularities reach amplitudes of approximately 10 percent and are found to break up into smaller dominant scale sizes in the horizontal westward direction than in the vertical direction. A steepening of the density waveform appears in the vertical direction. Perturbed electron velocities form vortex patterns and reach magnitudes comparable to the mean electrojet drift speed. (auth)