Simultaneous observations of E-region irregularities by ground-based and rocketborne techniques

Night E region irregularities were observed in winter in Scandinavia using radar and rocket-borne probes. The power spectra of ionization variability differ, having spectral indicies of -5/3 on one night and 0 on another. The measurements were made after the decay of magnetic activity from + 300 to below + 100 gamma and in a trough of low ionospheric electric field. This means that the electrojet current and hence the generation of ion acoustic waves was locally weak and dying out. It is suggested that under these conditions the smaller scale inhomogeneities decay faster until an equilibrium is reached with energy derived from the decay of large scale waves in a manner analogous to the turbulent breakdown of neutral air flows.