Parametric analysis of nightside conductance effects on inner magnetospheric dynamics for the 17 April 2002 storm

[1] Numerous simulations were conducted in order to quantify the influence of nightside conductance morphology and intensity on the storm-time ring current and plasmasphere. The study focused on the moderate magnetic storm of 17 April 2002. The simulation results were compared against measurements of the ring current and plasmasphere in order to assess the accuracy as a function of conductance parameter setting. In particular, three data sets were used: Dst*, plasmapause location as extracted from IMAGE EUV snapshots, and IMAGE HENA flux observations for the 39 - 60 keV energy range. While no single simulation conducted for this study proved itself to be the best overall match to the selected data sets, many things were learned from the simulations. The most important scientific finding is that there is an optimal conductance level for maximal ring current intensity. Too little conductance leads to large shielding potentials that effectively inhibit ring current growth, while too much conductance leads to continual flow-through of the hot ions with no significant hot ion accumulation in the inner magnetosphere. It was found that the poleward shift of the high conductance region of the auroral oval was the most important factor affecting the data-model comparisons. The peak intensity of the auroral oval conductance was also determined to be a significant factor affecting model accuracy. Tilting the dawnside location of the oval equatorward with respect to its duskside latitude had little effect on the results, as did the setting for the uniformly applied baseline conductance. The high-latitude boundary condition for the potential solution was also found to have little influence on the results.