Investigating the Development of Localized Neutral Density Increases During the 24 August 2005 Geomagnetic Storm

We investigate localized thermospheric neutral density increases (or density spikes) developed during the 24 August 2005 geomagnetic storm and utilize a multi-instrument database for monitoring the underlying thermospheric, ionospheric, magnetospheric, and solar wind conditions. We study five scenarios occurring under eastward/westward B dominations and demonstrating the development of density spikes during various events. These scenarios show (1) a northern density spike associated with enhanced antisunward polar flows driven by dayside merging along old-open field lines during the initial phase, (2) some southern density spikes associated with enhanced sunward auroral flows caused by auroral brightening events during the storm initial phase and main phase, (3) two pairs of southern dayside-nightside density spike configuration associated with enhanced antisunward polar flows caused by dayside merging and nightside magnetotail reconnections along old-open field lines during the underlying substorm activity, and (4) a series of enhanced polar sunward flows developed in the polar cap driven by different processes during the recovery phase. We provide a detailed analysis of these events including the specification of underlying field aligned current systems, flow channel types, and auroral forms. Observational results demonstrate the various density spikes and their associated auroral forms and/or flow channels and thus provide a better understanding of their development during this intense geomagnetic storm