A Statistical Analysis of the Auroral Streamer Current System

Magnetosphere-ionosphere coupling is an important process that involves the transport of vast quantities of mass, energy, and momentum in the Earth's near-space environment. This transport involves extended, global sheets of electrical current that flows along the magnetic field lines. Many studies have discussed the magnetosphere-ionosphere coupling between the fast-moving earthward flows and the north-south oriented streamers in the ionosphere. However, only recently, the temporal evolution of the ionospheric current pattern, from the start to the end of the streamer, has been investigated through case studies, by combining the ionospheric current pattern with the magnetotail fast-moving earthward flows. In this study, we show the statistical spatial and temporal evolution of the ionospheric current pattern associated with north-south oriented streamers using simultaneous THEMIS (Time History of Events and Macroscale Interaction during Substorms) observations of fast-moving earthward flows within the magnetotail, Geostationary Operational Environmental Satellite observations, auroral all-sky images, and ionospheric equivalent current maps derived from ground magnetometer measurements. We show that the streamer related ionospheric field-aligned currents (FACs) are statistically almost equivalent in magnitude for the 38 events that were analyzed. Results show that the streamer related ionospheric FACs are statistically approximately similar in magnitude for 38 events. The duration of these events ranges from 2 to 21 min with a median value of 9 min.