A storm time assimilative mapping of ionospheric electrodynamics analysis for the severe geomagnetic storm of November 8–9, 1991

Global parameters are obtained for the November 8–9, 1991 severe geomagnetic storm with the application of a slightly modified version of the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) data inversion model. Inputs to the model include ground magnetometer data, satellite electron precipitation data, satellite ion drift data, and ion drift velocities obtained from radar measurements. We compare two of the AMIE computed parameters, the total Joule heating and the polar cap potential, to both the AE (12) index and the AE AMIE index, an AMIE modeled AE index created specifically for severe storm times. The equation obtained from a linear fit to the total Joule heating versus the AE AMIE index closely resembles other equations found during much less disturbed times using the AE (12) index. Our results using the AE (12) index appear to saturate at a level around 1300 nT. However, this saturation is associated with the calculation of the AE (12) index and not a physical result. An apparent saturation can also be seen in our comparison of the polar cap potential with the AE (12) index, but this is not the case when using the AE AMIE index. The comparison between the polar cap potential and the AE AMIE index yields an approximate linear relationship with a correlation coefficient of 0.80. From our results, we find that the magnitude of the auroral electrojets and the polar cap potential drop do not show signs of saturation at the activity levels that were present during the November 8–9, 1991 severe storm.