Investigation of fine-scale structure in the ionosphere

ine-scale, horizontal wave-like structures with a period of approximately 12 minutes, normalized amplitudes of 1-3%, and vertical wavelengths exceeding 30 km, have been found using high-resolution incoherent scatter radar techniques. These structures link sporadic E, an ion layer in the E-region of the ionosphere that is unpredictable in height, time, and concentration, and spread F, which is manifested by the spreading of traces on an ionogram. Recent observations show manifestations of small-scale electric fields including vertical streaks of ionization (termed ion rain), and oscillations in the tidal ion layer. The electric fields likely result from the Perkins instability, a process by which the force supporting the F-region, eastward current crossed with the Earth's magnetic field...