Simultaneous Action of X- and O-Mode HF Pump Waves on the High-Latitude Upper (F-Region) Ionosphere at EISCAT

We report experimental results from multi-instrument diagnostic tools related to phenomena in the high latitude ionosphere F-region, induced by simultaneous action of powerful extraordinary (X-mode) and ordinary (O-mode) polarized HF radio waves at EISCAT (European Incoherent SCATter) during magnetically quiet background geophysical conditions. pump were injected towards magnetic zenith a frequency 5.423 MHz, which was just below critical F2 layer when excitation X- O-mode possible. In course experiment, effective radiated power (ERP) X-mode wave 130.5 MW, while portion ERP 29.9 MW (about 20% full ERP). It found that lead effects typical for both waves. Namely, small-scale field-aligned irregularities due thermal parametric (resonance) instability downshifted maximum (DM) component wideband stimulated electromagnetic emission (WSEE) spectra, pumping, observed, together with multiple ion gyro-harmonic structures narrowband (NSEE) spectra. These latter recorded large (more than 1000 km) distance EISCAT/heating facility, only an pumping. The obtained are compared “pure” heating discussed detail.