Dipolarizing flux bundles in the cis‐geosynchronous magnetosphere: Relationship between electric fields and energetic particle injections. Issue 2 (27th February 2016) - Liu, Jiang
Abstract: Dipolarizing flux bundles (DFBs) are small flux tubes (typically <3 RE in X GSM and Y GSM ) in the nightside magnetosphere that have magnetic field more dipolar than the background. Although DFBs are known to accelerate particles, creating energetic particle injections outside geosynchronous orbit (trans‐GEO), the nature of the acceleration mechanism and the importance of DFBs in generating injections inside geosynchronous orbit (cis‐GEO) are unclear. Our statistical study of cis‐GEO DFBs using data from the Van Allen Probes reveals that just like trans‐GEO DFBs, cis‐GEO DFBs occur most often in the premidnight sector, but their occurrence rate is ~1/3 that of trans‐GEO DFBs. Half the cis‐GEO DFBs are accompanied by an energetic particle injection and have an electric field 3 times stronger than that of the injectionless half. All DFB injections are dispersionless within the temporal resolution considered (11 s). Our findings suggest that these injections are ushered or produced locally by the DFB, and the DFB's strong electric field is an important aspect of the injection generation mechanism. Key Points: Dipolarizing flux bundles (DFBs) have significant occurrence rates inside the geosynchronous orbit The average electric field of DFBs with injections is 3 times that of those without All energetic particle injections accompanying DFBs are dispersionless