Observational Evidence of Transient Lobe Reconnection Triggered by Sudden Northern Enhancement of IMF Bz

Abstract

AbstractIn general, lobe reconnection occurs under northward interplanetary magnetic field (IMF) Bz. However, what process can trigger lobe reconnection has not been fully understood. Using observations from SuperDARN radar and Defense Meteorological Satellite Program (DMSP) spacecraft, we found that (a) short‐term sunward ionospheric flow bursts observed by SuperDARN poleward of the cusp showed one‐to‐one correspondent with the sudden increase of the IMF Bz, (b) the sunward flow bursts observed by SurperDARN were associated with sunward ion drifts identified from the DMSP satellite, and (c) a cusp auroral spot, together with an inverse ion energy dispersion, was observed in association with one of the flow bursts. We suggest that these observations provide evidence that the lobe reconnections can be triggered by a sudden increase of the IMF Bz component. What’s more, we found that the reconnection signatures disappeared quickly after the IMF Bz enhancement being over, which indicates that the lobe reconnection triggered by the sudden increase of the IMF Bz is a transient process.