Geomagnetic storms produce large changes in the Earth’s ionosphere and thermosphere that can impact communications, satellite orbits, and navigation systems, as well as electric power grids. The capability of numerical models to reproduce the ionospheric disturbance during a geomagnetic storm depends mainly on accurately specifying the spatial and temporal variation of the high latitude electric fields and of auroral charged particle precipitation. These forcing parameters are not known with complete owing to imperfect observational knowledge.
Pedatella et al.  explore, for the first time, the consequences of the uncertainty in the forcing parameters upon key ionospheric parameters at low and mid latitude using an ensemble of simulations from the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model.
Results demonstrate that, during geomagnetically quiet periods, the uncertainty of the high latitude electric field can lead to changes of electron concentration at low and mid-latitudes which is small (less than 20 percent). But the variability in electron concentration typically doubles during a geomagnetic storm. The uncertainty in the flux of auroral charged particle precipitation is much more modest at high latitudes and has little impact on the uncertainty of electron concentration at mid and low latitudes.
Mechanisms involving neutral winds, electric fields and composition changes are responsible for the changes and uncertainties observed at mid and low latitudes but their relative importance changes as the storm evolves.
Understanding the impact of forcing uncertainty is significant for space weather since it can provide an estimate of the reliability of the simulations.
Citation: Pedatella, N. M., Lu, G., & Richmond, A. D. . Effects of high-latitude forcing uncertainty on the low-latitude and midlatitude ionosphere. Journal of Geophysical Research: Space Physics, 123, http://doi.org/10.1002/2017JA024683
—Alan Rodger, Editor, JGR: Space Physics