• DOI:10.1029/91GL02081
• Corpus ID: 44059827

The flywheel effect: Ionospheric currents after a geomagnetic storm

@article{Deng1991TheFE,
  title={The flywheel effect: Ionospheric currents after a geomagnetic storm},
  author={Wei Deng and Timothy L. Killeen and Alan G. Burns and Raymond G. Roble},
  journal={Geophysical Research Letters},
  year={1991},
  volume={18},
  pages={1845-1848}
}

• W. Deng, T. Killeen, +1 author R. Roble
• Published 1 October 1991
• Physics, Environmental Science
• Geophysical Research Letters

In the period following a geomagnetic storm the high-latitude, magnetospheric-driven convection pattern is normally weak. However, the neutral circulation, set up by ion-neutral momentum coupling during the main phase of the storm, may continue for several hours after the storm has ended. This persistent neutral circulation has the potential to drive Hall currents for some hours. In this paper we investi- gate these "flywheel" currents by simulating a storm which occurred on the 23 rd of November 1982 using the National Center for Atmospheric Research Thermosphere Ionosphere General Circulation Model (NCAR-TIGCM). The resulting high-latitude, height-integrated Hal/currents are dominated by the neutral-wind-driven component for several hours after the end of main phase of the storm. The direction of these currents is reversed from normal. Analysis of the neutral and ion components of this current system indicates that the neutral component may drive as much as 80% of the high-latitude current system immediately after the storm has ended, and may continue to dominate this system for 4 to 5 hours. stant in the E-region for the transfer of momentum from the plasma to the neutral gas implies that the neutral winds that were forced by the ions during the main phase of the geomag- netic storm can persist for a long time after the cessation of magnetospheric-driven forcing, and may drive significant ionospheric and magnetospheric field-aligned currents over the polar cap in a way that is similar to that of the dynamo in low and middle latitudes. Lyons et al. (1985) studied these winds and they showed that, in practice, the neutral circulation in the high-latitude E region can drive a significant Hall current system for up to six hours after the cessation of strong magne- tospheric convection - the so-called neutral "flywheel" effect. Some experimental support for this concept exists in the results published by several authors (e.g. Maezawa, 1976; Zanetti, 1984), who showed that ionospheric currents can reverse direction when B z is northward. In this paper we extend the Lyons et a1.(1985) study to investigate the link between the neutral circulation and these reversed currents during the period following a geomagnetic storm.