Preprints
https://doi.org/10.5194/angeo-2021-19
https://doi.org/10.5194/angeo-2021-19

  07 Apr 2021

07 Apr 2021

Review status: a revised version of this preprint is currently under review for the journal ANGEO.

Polar tongue of ionisation during geomagnetic superstorm

Dimitry Pokhotelov, Isabel Fernandez-Gomez, and Claudia Borries Dimitry Pokhotelov et al.
  • German Aerospace Center (DLR), Institute for Solar-Terrestrial Physics, Neustrelitz, Germany

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

Dimitry Pokhotelov et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Reviewer comments', Anonymous Referee #1, 22 Apr 2021
    • AC1: 'Reply on RC1', Dimitry Pokhotelov, 11 Jun 2021
  • RC2: 'Comment on angeo-2021-19', Anonymous Referee #2, 16 May 2021
    • AC2: 'Reply on RC2', Dimitry Pokhotelov, 11 Jun 2021

Dimitry Pokhotelov et al.

Dimitry Pokhotelov et al.

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Short summary
During geomagnetic storms, enhanced solar wind and changes in interplanetary magnetic field lead to ionisation anomalies spreading across the polar regions. The superstorm of 20 November 2003 was one of the largest events in recent history. Numerical simulations of ionospheric dynamics during the storm are compared with plasma observations to understand the mechanisms forming the polar plasma anomalies. The results are important for understanding and forecasting space weather in polar regions.