The Effects of Storm-Enhanced Zonal Ion Drifts and Plasmaspheric Heat Flux on Middle-Latitude Ionospheric Trough

This study examines how enhanced zonal ion drifts and plasmaspheric heat flux influence mid-latitude ionospheric trough dynamics during geomagnetic storms using the Thermosphere Ionosphere Electrodynamic General Circulation Model coupled with a Subauroral Polarization Streams (SAPS) empirical model. Increasing SAPS-driven zonal ion drifts from ∼1 to 2 km/s deepened and expanded the trough longitudinally/latitudinally, reducing nighttime TEC by ∼20% within the trough. Ion temperatures doubled to ∼1,600 K under stronger SAPS due to increased frictional heating, while electron density depletion and temperature enhancements showed weaker responses owing to low electron density limiting electron-ion collisional heating. Doubling plasmaspheric heat flux amplified electron temperature by ∼120% (∼1,200 K) and reduced electron density by ∼80% (∼2 × 10⁵ cm⁻³), with minimal ion/neutral temperature changes from limited electron-neutral thermal coupling. Neutral temperature-driven atmospheric upwelling decreased O/N₂ ratios, further depleting electron density. These results highlight the critical role of SAPS-driven ion dynamics and plasmaspheric energy inputs in shaping storm-time trough morphology through distinct thermal and compositional pathways.