Mid-Latitude Dayside Ionospheric Response to Storm-Time Electric Fields

One way in which a geomagnetic storm may impact the ionosphere is through an expansion of the magnetospheric electric field to mid-latitudes. This mechanism was explored in detail by Heelis et al [2009], where it was shown that an electric field with a magnitude of just 1 mV/m at mid-latitudes is sufficient to produce a large increase in TEC on the dayside. This effect is brought about by the lifting of the ionosphere as dayside plasma is transported poleward under the influence of the eastward component of the expanded electric field; the lifting occurs because of the inclination of the magnetic field lines. At the time the above-mentioned article was written, the authors lacked a physics-based modeling capability for the behavior of the storm-time electric field at mid-latitudes, so a simple modified form of the Volland 2-cell model was used. In the present work we use the University of Michigan’s Hot Electron and Ion Drift Integrator (HEIDI) electric field model, along with the Utah State University Time Dependent Ionospheric Model (TDIM). The HEIDI model provides electric potential distributions spanning the northern mid-latitudes with a cadence of 30 minutes; these are used to drive the TDIM in carrying out mid-latitude simulations. The results are compared with model runs for the quiet-time ionosphere, as well as observations from ionosondes and ground-based GPS TEC receivers. ----------------- Heelis, R. A., J. J. Sojka, M. David, and R. W. Schunk (2009), Storm time density enhancements in the middle-latitude dayside ionosphere, J. Geophys. Res., 114, A03315, doi:10.1029/2008JA013690.