Foreshock transient impact on the magnetosheath, magnetosphere and ionosphere

We present multi-scale observations of a foreshock transient and its impact on the magnetosheath, magnetosphere and ionosphere, utilizing the data from Cluster, THEMIS, ground-based radars, and magnetometers. During the storm recovery phase on March 25, 2015, the Cluster spacecraft observed the foreshock transient at GSE (8, -0.5, -13) Re. Subsequently, THEMIS A and E, residing in the equatorial plane, detected large-scale high-speed jets in the postnoon sector between 7 and 9 Re from Earth. At geosynchronous orbit, GOES-13 crossed the magnetopause, during which strong poleward plasma convection and tongue of ionization (TOI) were detected by incoherent scatter radars at Prince George, Saskatoon, Kapuskasing, and Rankin Inlet stations and GPS total electron content (TEC) measurements. The signature of field-aligned currents was observed by ground magnetometers. These simultaneous observations indicate that the foreshock transient plays an important role in energy transfer between the solar wind, the magnetosphere, and the ionosphere. This event provides the first observational evidence that a foreshock transient can lead to significant disturbances in the coupled magnetosphere-ionosphere system, being an important ingredient in space weather.