FTE Generation for Predominantly East-West IMF

Numerous models have been proposed to explain the reconnection mechanisms that lead to the formation of Flux Transfer Events (FTEs) at the magnetopause. Most of these models can be classified into Multiple x-line Reconnection (MXR) or Single x-line Reconnection (SXR) models. In the MXR models multiple x-lines are present at the same time leading to the formation of flux ropes between these x-lines. SXR models assume a single x-line with bursty or time-varying reconnection rate. These phenomenological models are difficult to distinguish with data because there are generally not enough spacecraft available to cover the magnetopause. In this study we use the OpenGGCM global magnetosphere model to study the reconnection topology. We first verify the model by reproducing a series of FTEs that were observed by Cluster and Double Star 1 on May 8, 2004. We then show that the reconnection process that leads to the FTEs is best described by a Sequential Multiple x-line Reconnection (SMXR) process by which new a new x-line forms in the wake of a departing FTE, leading up to the next FTE. This model naturally explains the quasi-periodic nature of FTEs, the typical inter-FTE times, and the hemisphere preferences of FTEs dependent on dipole tilt and IMF orientation.