Observations of HF radio propagation at high latitudes and predictions using data-driven simulations

Researchers at the University of Leicester, Lancaster University and St Petersburg State University have developed various models that can be employed in HF radio propagation predictions. Signal coverage predictions make use of numerical ray tracing to estimate the ray paths through a model ionosphere that includes various ionospheric features prevalent at high latitudes (in particular patches, arcs, ionisation tongue, auroral zone irregularities and the mid-latitude trough). Modelling of D-region absorption is also included. GOES satellites provide information on X-ray flux (causing shortwave fadeout during solar flares) and precipitating energetic proton flux which correlates strongly with Polar Cap Absorption (PCA). Solar wind and interplanetary magnetic field measurements from the ACE or DSCOVR spacecraft provide geomagnetic index estimates used to model the location of both auroral absorption and the proton rigidity cutoff boundary that defines the latitudinal extent of PCA during solar proton events (SPE). This paper presents measurements and associated modelling for a 9 day period.