SAMI3 Ionosphere Model Validation Through Raytracing Analysis

The natural variability of the ionosphere affects HF radio technologies including communications and over-the-horizon radar (OTHR) surveillance. A robust, global ionospheric model is needed in order to characterize and predict ionospheric effects on HF signal propagation. This investigation tests the ability of the SAMI3 model to predict amateur radio communications links from the public Weak Signal Propagation Reporter (WSPR) database.
 
SAMI3 is a three-dimensional, global physics-based model of the ionosphere which predicts the ionospheric electron density and other parameters based on observed and climatological drivers. The WSPR database is populated through an amateur radio system in which operators probe radio frequency propagation conditions using very low power (QRP/QRPp) transmissions.
 
In order to investigate the fidelity of SAMI3, raytracing analysis of verified global HF links was performed using the SAMI3-defined ionosphere. Tx - Rx links that were known to be successful at a given time, as well as links that were known to be unsuccessful, were analyzed. The raytracing results were then compared to the verified data in order to determine how well the SAMI3 ionospheric model represented the actual ionosphere at the specific locations and times corresponding to each link pair. Initial results indicate approximately 50% agreement between the verified data and the SAMI3-driven raytracing results.