Climatology of HF propagation characteristics at very high latitudes from SuperDARN observations

Conventional forecasting of high-frequency (HF, 3–30 MHz) radio wave propagation is based on a combination of ionospheric and propagation models. However, at very high latitudes this approach is seriously undermined by the intrinsically dynamic ionospheric conditions regularly perturbed by energetic particle precipitations and strong electric fields. From this perspective, the multi-year observations of HF propagation characteristics by Super Dual Auroral Radar Network (SuperDARN) radars across auroral and polar cap regions represent a unique opportunity for systematic validation of the conventional approach, as well as for creating an empirical propagation model directly from the radar observations. Qualitative identification and quantitative characterization of the propagation modes requires an accurate knowledge of the vertical angle of arrival (elevation angle) across the high-latitude part of the radar network. This information has become available only in recent years, facilitated by the development of reliable data-based calibration techniques for SuperDARN interferometry. We present the solar-cycle/seasonal/diurnal climatology of HF propagation characteristics at very high latitudes derived from two-frequency observations by the Rankin Inlet SuperDARN radar.