Speaker: Zbysek Mosna
Abstract:
Sporadic E layers (Es) are thin sheets of enhanced electron concentration located in the height of the ionospheric E region. The maximum plasma frequency of the Es layer (i.e. the critical frequency foEs) often exceeds the E-layer critical frequency (foE) and even the F-layer critical frequency (foF2), which underlines the significance of the Es layers in the propagation of electromagnetic signals. Sporadic layers are largely affected by the wave activity of the neutral atmosphere which can be observed most notably in tidal and planetary modes.
We will present some results from ground-based measurements at the mid-latitude ionospheric observatory in Pruhonice, Czech Republic. Ionospheric drift measurements, carried out with the ionosonde, reveal different plasma velocities in the Es layer and the E region. Planetary wave modes have been observed during several time intervals on a large range of heights - from the stratosphere up to the Es region. Also, a comparison between ground and satellite measurements is made for the Es critical frequency (foEs), blanketing frequency (fbEs), and height (hEs). The analysis of the Es parameters during the current 24-th solar cycle shows their clear dependence on the phase of the cycle.
Date: 8 August 2018
