CASCADES-II sounding rocket study of auroral poleward boundary intensifications

The CASCADES-II sounding rocket was launched on 20 March 2009 at 11:04:00UT from the Poker Flat Research Range. The payload had five sub-payloads for multipoint measurements of auroral dynamics and structure. The ground-based cameras under the rocket trajectory show auroral signatures that can be described as a series of Poleward Boundary Intensifications, which are repeated brightenings along the poleward edge of the auroral oval that may move equatorward [Lyons et al. 1999]. In a case study by Zesta et al. [2002] PBIs are split into two categories: equatorward extending or nonequatorward extending, based on MSP observations. The rocket is seen to fly through both types of PBIs, which show fundamental differences in the in situ and allsky image data, ranging from inverted-V type aurora in the equatorward extended events to alfvenic aurora in the nonequatorward extending events. This would suggest that each type relates to different magnetotail dynamics. The CASCADES-II rocket study will serve as a detailed case study of the relation between Bursty Bulk Flows (BBFs) in the tail and equatorward extending PBIs. Three THEMIS satellites, conjugate with the rocket footprint, observe BBFs at the time of flight. This study will also compare in situ particle data from multiple payloads and ground optical data, providing a detailed analysis of the less-studied nonequatorward extending PBIs and their association to instabilities at the separatrix boundary.