Modeling electron density at high latitudes: development of the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM)

Abstract

The ionosphere is an important medium for high frequency (HF) radio communications and remote sensing, as well as a hindrance to the use of the Global Positioning System (GPS); thereby, these systems require accurate ionospheric models in order to function. The highly complex nature of the high latitude ionospheric dynamics, combined with an extreme scarcity of data in the high-latitude region, has, in the past, made this area virtually impossible to model accurately. With the recent explosion of ionospheric remote sensing instruments in the polar region, it has now become possible to monitor these regions with high spatial resolution. Today there exist no accurate ionosphere models specific to the high latitude region and de facto standard ionospheric models, such as the International Reference Ionosphere (IRI), have been shown to be inaccurate at high-latitudes. Here we present the methodology and performance of the new Empirical Canadian High Arctic Ionospheric Model (E-CHAIM), a 3D high latitude electron density model intended to replace the use of the IRI in these regions. To this end, we make use of every available high latitude radio remote sensing ionospheric data set dating back to the very first observations of the ionosphere from 1931 at the Slough ionosonde in Ditton Park, UK. Specifically, we examine lessons learned from the short comings of other empirical ionospheric models, discuss the reasoning behind the parameterizations used, and provide comparisons between the model and real observations that weren’t included in model fitting. Overall, the E-CHAIM model is demonstrated to represent a significant improvement over current standards in the representation of the topside and F2-peak of the ionosphere, while providing comparable performance to current standards in the representation of the bottomside shape.