Comparison Between the Integrated Ion Outflow Fluxes from the North and South Hemispheres Under Sustained Geomagnetically Active Conditions

Abstract:

The Generalized Polar Wind (GPW) model is used to simulate the polar ionosphere during the September/October 2002 storm. The simulation period is near equinox when the north and south hemispheres are similarly exposed to solar radiation. We present a model simulation of the eight day period 2002 September 27 (DOY 270) through October 4 (DOY 277). The first three days have relatively quiet magnetic activity as indicated by low Kp values. The fourth day (270) is moderately active, and over the last four days (1-4 October) a strong magnetic storm takes place where Kp reaches values greater than 7 and Dst reaches values below -170. The GPW model was utilized to simulate the behavior of the plasma outflow from both hemispheres over the eight-day period. This storm differs from idealized storm that was the subject of a number of previous studies by Schunk and coauthors in the following ways. First, the interplanetary magnetic field changed in a complex manner in contrast to the previous studies where the IMF remained in the negative z direction. Second, Kp variation is more complex than the previous investigations. Third, the simulation period of eight days is much longer than the previous simulations (less than 18 hours). Finally, both hemispheres are considered, in contrast to previous simulations that investigated the northern hemisphere only. This investigation focuses on the variation of the integrated flux (from the poles to 45 degrees of latitude). We discuss how the integrated flux depends on the ion species (O⁺ vs. H⁺) and on the hemisphere (north vs. south). We also investigated the integrated flux dependence on the physical conditions, e.g., Kp, Dst universal time, etc. This statistical approach helped extract important simple conclusions from the complex behavior of the ion outflow during real a storm.