ALTERNATIVE INTERPRETATION OF IONOSPHERIC ALFVEN RESONANCE

摘要

We discuss an alternative interpretation for ELF-ULF electromagnetic resonance structure known as ionospheric Alfven resonance, which is observed in horizontal magnetic field components at ultra low frequency (ULF). Ionospheric Alfven resonance (IAR) is observed as a succession of peaks in spectra of natural ULF radio noise. Such peaks are usually attributed to plasma waves (Alfven waves) trapped in the magnetized ionosphere between its lower and upper boundaries. We discuss other mechanism for the IAR, which implies the radio (electromagnetic) waves traveling through the plasma. Spectral maxima appear without premise of Alfven waves (or any other plasma waves) trapped in the ionosphere. The field enhancement originates from interaction between partial reflections from the upper and lower boundaries of the ionosphere. Such a mechanism explains all known results of experimental observations. A conclusion is made that additional investigations are necessary to prove that IAR signal originates indeed from the ionospheric plasma waves.