Polar tongue of ionisation during geomagnetic superstorm

Abstract. During the main phase of geomagnetic storms, large positive ionospheric plasma density anomalies arise at middle and polar latitudes. A prominent example is tongue ionisation (TOI), which extends poleward from dayside storm-enhanced (SED) anomaly, often crossing cap streaming with convection flow into nightside ionosphere. fragmentation TOI anomaly contributes to formation patches partially responsible for scintillations satellite positioning signals high To investigate this intense numerical simulations neutral dynamics during superstorm 20 November 2003 are performed using Thermosphere Ionosphere Electrodynamics Global Circulation Model (TIE-GCM) coupled statistical parameterisation high-latitude convection. The simulation results reproduce features consistently observations total electron content tomography, published previously by authors. It demonstrated that fast uplift, due electric expanded subauroral mid-latitudes, serves as a primary feeding mechanism while complex interplay between electrodynamic wind transports shown contribute mid-latitude SED anomaly. This contrasts relatively smaller where impact on appears more pronounced. suggested better representation superstorms needed. discussed in context space weather modelling.