Journal metrics

Journal metrics

  • IF value: 1.621 IF 1.621
  • IF 5-year value: 1.614 IF 5-year 1.614
  • CiteScore value: 1.61 CiteScore 1.61
  • SNIP value: 0.900 SNIP 0.900
  • SJR value: 0.910 SJR 0.910
  • IPP value: 1.58 IPP 1.58
  • h5-index value: 24 h5-index 24
  • Scimago H index value: 80 Scimago H index 80
Ann. Geophys., 30, 177-202, 2012
https://doi.org/10.5194/angeo-30-177-2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.
Regular paper
17 Jan 2012
Storm-time ring current: model-dependent results
N. Yu. Ganushkina1,2, M. W. Liemohn1, and T. I. Pulkkinen3 1Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI, USA
2Finnish Meteorological Institute, Helsinki, Finland
3Aalto University, School of Electrical Engineering, Espoo, Finland
Abstract. The main point of the paper is to investigate how much the modeled ring current depends on the representations of magnetic and electric fields and boundary conditions used in simulations. Two storm events, one moderate (SymH minimum of −120 nT) on 6–7 November 1997 and one intense (SymH minimum of −230 nT) on 21–22 October 1999, are modeled. A rather simple ring current model is employed, namely, the Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM), in order to make the results most evident. Four different magnetic field and two electric field representations and four boundary conditions are used. We find that different combinations of the magnetic and electric field configurations and boundary conditions result in very different modeled ring current, and, therefore, the physical conclusions based on simulation results can differ significantly. A time-dependent boundary outside of 6.6 RE gives a possibility to take into account the particles in the transition region (between dipole and stretched field lines) forming partial ring current and near-Earth tail current in that region. Calculating the model SymH* by Biot-Savart's law instead of the widely used Dessler-Parker-Sckopke (DPS) relation gives larger and more realistic values, since the currents are calculated in the regions with nondipolar magnetic field. Therefore, the boundary location and the method of SymH* calculation are of key importance for ring current data-model comparisons to be correctly interpreted.

Citation: Ganushkina, N. Yu., Liemohn, M. W., and Pulkkinen, T. I.: Storm-time ring current: model-dependent results, Ann. Geophys., 30, 177-202, https://doi.org/10.5194/angeo-30-177-2012, 2012.
Publications Copernicus
Download
Share