Statistical study of Pc1-2 wave propagation characteristics in the high-latitude ionospheric waveguide

Propagation of ULF Pc1-2 geomagnetic pulsations in the ionospheric waveguide (duct), centered around the F₂ region altitude of maximum ionospheric electron density, is studied using the data obtained from a ground array of five search coil magnetometers in Antarctica distributed over a very extensive range of geomagnetic latitudes from subauroral to polar cap (-62° to -87°, spanning 2920 km geographically). A statistical study including a total of 138 Pc1-2 wave ducting events in 2007 presents wave power attenuation factors that vary between ∼10 and 14 dB/1000 km and the change of polarization during the wave propagation under different ionospheric sunlight conditions. It is also shown that the frequency cutoff of the wave events in the waveguide is dependent on the ionospheric conductivity, and the wave power attenuation increases with increasing frequency. In addition, it appears that initial propagation direction is related to attenuation, which supports the idea that meridional propagation is most efficient as predicted in previous studies. The results show the observations of ducted waves over such an unprecedented latitudinal extent along a magnetic meridian, which have rarely been measured before, and thus provide very important information in regard to wave ducting under various ionospheric conditions.