THE MAJOR MAGNETIC STORM OF MARCH 13-14, 1989 AND ASSOCIATED IONOSPHERE EFFECTS

The geomagnetic storm of March 1989 was the largest geomagnetic storm of the decade and one of the largest of the century. We review many of the "high-latitude" ionospheric observations that were made during this storm. Most of the data presented here comes from the polar-orbiting satellites of the Defense Meteorological Satellite Program (DMSP) series. A review of the DMSP data shows.that most of the high-latitude, top-side ionospheric disturbance occurred on March 13 and 14. The magnitudes of the particle energy flux (ergs cm-2) (1 erg = 10(-7) J) and Joule heating were not unusually large for a storm, but the area of the energy deposition, and thus the total energy deposition, was extremely large. At the peak of the storm (minimum in D(st) (disturbance with storm time) and midnight boundary indices) the auroral particle precipitation extended down to magnetic latitudes of 40.1-degrees or L = 1.71 while the polar edge of the auroral zone expanded poleward only slightly. The storm was also a period of intense, hemispherically symmetric polar rain fluxes. The auroral electric field was clearly observed down to magnetic latitude of 35-degrees. This is consistent with the auroral electrojet (AE) current density and the AE index having a saturation level beyond which the index will increase slowly or not at all as more energy is transferred from the solar wind to the magnetosphere, but the cross polar-cap potential during this storm shows no evidence of saturation. There are only two visible light images from DMSP available near the peak of the storm. These images and one UV image from the Dynamics Explorer (DE) satellite at approximately the same time show the distribution of the aurora just after the peak of the storm. Comparison of the DMSP particle data with the DE-1 UV image indicates that the bifurcation of the auroral luminosity in the UV image is probably an effect of the DE-1 UV instrument's sensitivity limits; the DMSP data show no evidence for bifurcation of the auroral zone.