Empirical modeling of a CIR-driven magnetic storm

M. I. Sitnov, N. A. Tsyganenko, A. Y. Ukhorskiy, B. J. Anderson, H. Korth, A. T. Y. Lui, P. C. Brandt

Research output

33 Citations (Scopus)

Abstract

The empirical analysis of structure and evolution of the geomagnetic field and underlying electric currents during the 8-11 March 2008 magnetospheric storm, driven by a corotating interaction region, is presented. It is based on the high-resolution geomagnetic field model TS07D (http://geomag_field.jhuapl.edu/model/) and the low-altitude mapping of field-aligned currents obtained using Iridium satellites. Compared to storms, driven by coronal mass ejections, the equatorial currents are found to be overall more dawn-dusk symmetric. Only in the early main phase a moderate hook-like westward current flowing from the Region-2 inflow area on the dawn side to the dusk/afternoon magnetopause is detected, along with an eastward current near the pre-noon magnetopause. New tail-type currents are found to dominate the storm-time magnetosphere in early main and recovery phases at the moments of strong peaks of the solar wind dynamic pressure. Similar effects, found in CME-driven storms, coincide in time with the plasma sheet density bursts. A clear distinction between the periods dominated by the partial ring current and the tail-type currents seen in the model agrees with the Iridium data that indicate a significant reduction and contraction of the field-aligned current pattern in the latter case. Overall small magnitudes of the total field-aligned currents, with rather transient enhancements, appear to be the most distinctive feature of CIR-driven storms. Comparison between the model and observations made by five THEMIS probes shows good agreement on storm timescales. Moreover, every deviation arising during a substorm reveals characteristic signatures of the tail current sheet thinning and dipolarization.

Original languageEnglish
Article number07231
Pages (from-to)A07231_1-20
Number of pages20
JournalJOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
Volume115
Issue numberA7
DOIs
Publication statusPublished - 30 Jul 2010

Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)

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