Magnetic activity in Canada during the solar- terrestrial disturbance of 24-25 March 1991

Abstract

The solar-terrestrial event of 22-25 March 1991, was one of the largest this solar cycle, producing a very strong particle flux, a second inner radiation belt, and a large geomagnetic disturbance. This caused solar panel degradation and other satellite malfunctions as well as communication and power system problems. This report examines the resulting magnetic disturbance observed across Canada on 24-25 March, presenting stack plots of the temporal variations and using equivalent current plots to map the spatial characteristics of the disturbance. A notable feature of the results is that the largest magnetic field variations occurred in the polar cap and not, as is more common, in the auroral zone. These polar cap magnetic variations are attributed to Hall currents in the ionosphere resulting from the enhanced convection of field lines across the polar cap. The extreme magnitude of the polar cap disturbance indicates the severity of the solar wind plasma cloud interaction with the earth's magnetosphere.

Nighttime Geomagnetic Response to Jumps of Solar Wind Dynamic Pressure: A Possible Cause of Québec Blackout in March 1989

“…However, to date, we do not know the solar wind condition and the polarity of IMF B z for the event. In the earlier times, Boteler and Jansen (1993) showed a clear structure of the equivalent current system that westward currents flow at low latitudes and eastward currents flow at high latitudes in Figure 4c of their paper, which is similar with the Hall current vortex shown in our simulations. According to our results, one point to be emphasized is that the MI‐associated ionospheric current alone can cause this structure, small positive magnetic disturbances at high latitudes and large negative ones at a bit lower latitudes, that resembles the one observed in Canada.…”