Imprints of Electric Field Models on Wedge‐Like Ion Structures: Comparing SWMF, Weimer05, and Volland‐Stern in the Inner Magnetosphere

Abstract

Recent spacecraft observations and simulations have identified wedge‐like ion spectral structures in the inner magnetosphere and their sources in the magnetotail. However, simulations employing the Volland‐Stern (VS) convection electric field model systematically misplace these structures, exhibiting offsets in radial penetration depth compared to observations. Here we reanalyze the 3 February 2013 event observed by Van Allen Probes using backward tracing simulations driven by three convection electric field models: the Space Weather Modeling Framework (SWMF), Weimer05, and VS. Our results demonstrate that substorm‐injected ions driven by SWMF electric fields penetrate as deeply as observed and reproduce a comparable energy upper limit, showing a better performance than the Weimer05 and VS models. While previous studies attributed wedge‐like structures to discontinuous, long‐duration (over 10 hr) injections and the energy‐dependent accessibility of injected ions, we find that such structures can also arise from short‐duration (several hours) injections that become detained within the expanded plasmasphere and undergo prolonged eastward drift around the Earth from the nightside magnetotail. Differences in drift time modulate the morphology of the injected ion populations, suggesting an intrinsic evolutionary relationship between wedge‐like and finger‐like features.