Speaker
Description
The University of Calgary operates a suite of ground-based instruments that together provide a uniquely integrated view of the high-latitude ionosphere during space weather events. Multi-spectral auroral imagers and meridian spectrographs spanning 59°–71° geomagnetic latitude deliver high-cadence optical diagnostics of particle precipitation across multiple emission lines [Gillies et al., 2019; Liang et al., 2024]. Hyperspectral imaging riometers provide spectrally resolved cosmic noise absorption, offering independent, quantitative constraints on energetic particle deposition into the D-region. GNSS scintillation receivers distributed across the network characterize ionospheric plasma structuring and total electron content variability on timescales directly relevant to space weather impacts. Operating in concert, these instruments span precipitation, absorption, and plasma irregularities — delivering the multi-diagnostic observational context needed to constrain and validate physics-based space weather models.
The TREx Auroral Transport Model (TREx-ATM) [Liang et al., 2016, 2021, 2022; 2026] was purpose-built to exploit this multi-wavelength architecture. Compared to other existing electron transport codes ( (e.g., B3C and GLOW) that do not fully self-consistently evolve the ionospheric plasma state and/or have limitations in precipitation electron energies (typically no more than a few tens keV), TREx-ATM is a time-dependent model that self-consistently computes electron density, plasma temperature, and ionospheric conductivity profiles from first principles [Liang et al., 2022], and is extended to the relativistic energy range up to 10 MeV (Liang et al., 2026). The use of multiple emission lines simultaneously enables not only the derivation of precipitation mean energy and energy flux, but also independent constraint of the neutral O/N₂ ratio — a key source of error in competing inversion schemes [Liang et al., 2021 AGU]. Additionally, TREx-ATM incorporates coupled proton-hydrogen-electron transport, extending its inversion capacity to mixed precipitation regimes and enabling self-consistent conductance calculation for proton aurora [Liang et al., 2024, JGR]. A kinetic treatment of interhemispheric secondary electron transport provides further physical fidelity beyond two-stream approximation models.
Applied to the University of Calgary observations, this framework produces time-evolving, 2D maps of precipitation parameters and ionospheric conductances — quantities central to space weather specification and forecasting. These model-derived products are complemented by D-region absorption maps from the hyperspectral riometer network and TEC-based ionospheric products including tomographic reconstructions (e.g., UCTOMO), together providing a multi-layer characterization of ionospheric state from the D-region through the F-region. We discuss how this integrated observational and modeling capability can contribute to operational space weather efforts, including event-driven ionospheric specification and the potential for systematic precipitation characterization during geomagnetic activity.
| Numerical model | TREx-ATM + Sensors |
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