ИСТИНА

The spectral resonant structure in the frequency range 0.5-5 Hz, caused by the occurrence of the ionospheric Alfven resonator (IAR), is a ubliquitous, but not very regular phenomenon. We analyze clear IAR signatures at low-latitude stations Moshiri and Paratunka equiped with sensitive search-coil magnetometers. To reveal the fine structure of Pc1 emission we have applied the dynamic FFT and wavelet spectra, static power spectra, and polarization spectrum. For several selected days we monitored the time evolution of spectral structure of the IAR pattern. These results are compared with the predictions of the realistic model of IAR based on the numerical solution of coupled MHD/electrodynamic equations in the system ionosphere-atmosphere-ground, modeled with IRI-derived profile. This joint analysis raises some important questions about possible mechanisms of the IAR excitation, and nature of spectral resonant strucuture of Pc1 emission.