Physics Dept Seminar

April 10, Monday

Modelling to Support High Latitude Radio Propagation Studies:

How Far Can Empirical Methods Take Us?

Dr. David Themens

University of Birmingham, U.K

(Terrestrial Physics, Host: Perry)

Time: 11:45 am - 12:45 pm with 11:30 am teatime

Room: ECE 202

The plasma in the upper atmosphere, called the ionosphere, has the unique property of being a highly refractive medium for electromagnetic signals in the High Frequency (HF) band (3–30 MHz). This property allows one to use the ionosphere as a reflector for signals in this band, enabling long range (1000s of km) communications, as well as enabling long-range remote sensing systems, like Over-the-horizon Radar (OTHR). Due to the dependence of these systems on the ionosphere, however, they are heavily reliant on our capacity to model the ionosphere that their signals propagate through. At mid latitudes, climatological models, like the International Reference Ionosphere, are generally reliable and can be used under most quiet conditions; however, at high latitudes, where the ionosphere is heavily driven by external forcing from the magnetosphere and solar wind above, as well as the atmosphere below, ionospheric models have traditionally performed quite poorly and cannot be used to support operational systems, like OTHR. To mitigate this issue, we have developed the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM) to prescribe the climatological state of the ionosphere. To further capture ionospheric weather, an advanced data assimilation system (A-CHAIM) was later integrated into E-CHAIM, and semi-physical modules have been developed to integrate additional phenomena, including auroral particle precipitation and solar energetic proton precipitation. In this talk, we will examine the effects of various high latitude ionospheric dynamics on HF radio propagation at high latitudes, spanning their impact on the absorption of these signals and on scientific and operational radar systems, such as the Super Dual Auroral Radar Network (SuperDARN).