Different boundary layers at the high latitude magnetosphere behind the cusp

During southward interplanetary magnetic field (IMF), the electron and ion boundary are separated near the dayside boundary layer. Here we show observations at the high latitude magnetosphere tailward of the cusp during northward IMF. We find that the ion edge is observed firstly and then the electron edge is found by Cluster. Detailed analysis indicates that this is caused by the reconnection at the high latitude. The relationship between the observations and the aurora data is also discussed. A global simulation shows that these observations in different regions might be closely related to each other.