An analysis of magnetic reconnection events and their associated auroral enhancements

Abstract

An analysis of simultaneous reconnection events in the near‐Earth magnetotail and enhancements in the aurora is undertaken. Exploiting magnetospheric data from the Geotail, Cluster, and Double Star missions, along with auroral images from the IMAGE and Polar missions, the relationship between a reconnection signature and its auroral counterpart is explored. In this study of 59 suitable reconnection events, we find that 43 demonstrate a clear coincidence of reconnection and auroral enhancement. The magnetic local time (MLT) locations of these 43 reconnection events are generally located within ±1 h MLT of the associated auroral enhancement. A positive correlation coefficient of 0.8 between the two MLT locations is found. The enhancements are localized and short‐lived (τ≤10 min) and are as likely to occur during the substorm process as in isolation of a substorm. No significant dependence of the reconnection or auroral enhancement location on the dusk‐dawn components of the solar wind velocity (Vy), IMF (By) or local By or Vy, as measured by the reconnection‐detecting spacecraft, is found.

Physical Processes of Meso-Scale, Dynamic Auroral Forms

“…However, the spatial ordering of both streamers and localized brightenings with respect to the flow channel is the same, suggesting that auroral brightenings are also associated with the upward FAC region on the duskward flank of the BBF. Other studies have shown similar correspondence and MLT offsets between auroral enhancements and fast flows or reconnection signatures in the magnetotail (Ieda et al 2001(Ieda et al , 2008Case et al 2017), but did not explicitly examine auroral streamers. These results may reflect an observation bias, with global auroral imagers unable to resolve the detail of narrow auroral streamers, particularly when the auroral oval is relatively narrow.…”