Structure and dynamics of sporadic layers of ionization in the ionospheric E region



[1] Layers of ionization that appear in the ionospheric E region sporadically in time have been named sporadic-E layers, or Es. These sporadic ionization layers play a crucial role in small-scale irregularity generation (as they guarantee a plasma density gradient necessary for gradient-drift processes to develop) and in providing reliability of radio communication and navigation. Despite the fact that Es layers have been studied since the late sixties, a method to visualize the Es horizontal structure was suggested for the first time only recently [Kagan et al., 2000]. In the present paper we propose a new type of experiment for the reconstruction of the patchy-type Es structure and dynamics using a combination of the above-mentioned method with the method of artificial periodic irregularities (API) [Belikovich et al., 1999]. This combined method allows us for the first time to carry out Es tomography, to trace the three-dimensional (3-D) dynamics of sporadic ionization clouds and their associated 3-D neutral motions, and to study the effects of high-frequency radio waves on the sporadic-E layers. The procedure includes recording of the Es horizontal structure and dynamics with an all-sky camera via radio-wave-induced optical emissions in combination with measurements of the Es vertical structure and dynamics by the API method. Both methods complement each other and can be used simultaneously. The experiment is to be equipped with a powerful HF radio wave transmitter, all-sky cameras, an ionosonde, and an HF digital receiver.