Global Empirical Picture of Magnetospheric Substorms Inferred From Multimission Magnetometer Data

TitleGlobal Empirical Picture of Magnetospheric Substorms Inferred From Multimission Magnetometer Data
Publication TypeJournal Article
Year of Publication2019
AuthorsStephens, GK, Sitnov, MI, Korth, H, Tsyganenko, NA, Ohtani, S, Gkioulidou, M, Ukhorskiy, AY
JournalJournal of Geophysical Research: Space Physics
Date Published01/2019
KeywordsCurrent sheet thinning; Data‐mining; Magnetotail dipolarization; Storm‐substorm relationship; substorm current wedge; substorms; Van Allen Probes
AbstractMagnetospheric substorms represent key explosive processes in the interaction of the Earth's magnetosphere with the solar wind, and their understanding and modeling are critical for space weather forecasting. During substorms, the magnetic field on the nightside is first stretched in the antisunward direction and then it rapidly contracts earthward bringing hot plasmas from the distant space regions into the inner magnetosphere, where they contribute to geomagnetic storms and Joule dissipation in the polar ionosphere, causing impressive splashes of aurora. Here we show for the first time that mining millions of spaceborne magnetometer data records from multiple missions allows one to reconstruct the global 3‐D picture of these stretching and dipolarization processes. Stretching results in the formation of a thin (less than the Earth's radius) and strong current sheet, which is diverted into the ionosphere during dipolarization. In the meantime, the dipolarization signal propagates further into the inner magnetosphere resulting in the accumulation of a longer lived current there, giving rise to a protogeomagnetic storm. The global 3‐D structure of the corresponding substorm currents including the substorm current wedge is reconstructed from data.
Short TitleJ. Geophys. Res. Space Physics

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