Bursty bulk flow ionospheric impacts from triple-conjunctive observations

Abstract. Substorms are the regular reconfiguration of the Earth's geomagnetic space environment, and magnetosphere-ionosphere coupling is integral to the substorm chain. Bursty bulk flows (BBFs) are mesoscale fast plasma flows that are released from magnetic reconnection sites in the magnetotail during substorms, and they couple to the ionosphere through field aligned current (FAC) systems. BBFs may drive localised changes to the ionospheric plasma, such as velocity flows or changes to the local temperature, density and conductivity, but determining the specific ionospheric effects of a given BBF and their associated FAC is a complex undertaking. In this study we identify triple-conjugate observations of BBF detections within the magnetotail, FAC observations in low Earth orbit and ground-based radar stations that observe the local ionospheric plasma in order to evaluate the different components of the coupled BBF-FAC-ionosphere system. We evaluate over 11000 BBFs and identify only 13 events that satisfy our conjunctive criteria. We perform detailed analysis of one of these BBFs, which occurred in the recovery phase of a relatively weak substorm, to evaluate the FAC associated with this BBF and its ionospheric impacts. Multiple FAC signatures were observed that are associated with the BBF, in addition to variations in the ionospheric velocity and temperature. There is an ongoing need for coordinated observations of the coupled BBF-FAC-ionosphere system to further distinguish the ionospheric impacts of BBFs from broader substorm dynamics.