Modelling Absorption Loss in the High-Latitude Ionosphere for Over-the-Horizon Radar (OTHR)

Over-the-Horizon Radar (OTHR) uses high frequency (HF) radio wave propagation to detect targets up to thousands of kilometers away through ionospheric refraction and reflection. However, OTHR operation at high latitudes is impeded by irregular and variable enhancements to the electron density from precipitation in the auroral region, increasing the ionospheric absorption of HF radio waves and reducing the usable frequency range. A precipitation enhanced E-layer model was developed for the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM) to improve upon the electron density profile at lower altitudes. In this paper, the monthly median absorption is modeled for feasible operating frequency and elevation angle radar parameters to assess the effect of ionospheric absorption on OTHR in Canada.