Relative contributions of large-scale and wedgelet currents in the substorm current wedge

Earth, Planets and Space

卷:72

L. R. Lyons¹  J. M. Weygand²  V. Angelopoulos²  Y. Nishimura³  E. F. Donovan⁴  C. Gabrielse⁵ 

[1] Department of Atmospheric and Oceanic Sciences, University of California;

[2] Department of Earth, Planetary and Space Sciences, University of California;

[3] Department of Electrical and Computer Engineering and Center for Space Physics, Boston University;

[4] Department of Physics and Astronomy, University of Calgary;

[5] The Aerospace Corporation;

关键词: Substorm current wedge (SCW);    Field-aligned current (FAC);    Westward traveling surge (WTS);    Plasma sheet;    Bursty bulk flow (BBF);   

DOI  :  10.1186/s40623-020-01234-x

来源: DOAJ

【 摘 要 】

Abstract We examined how much large-scale and localized upward and downward currents contribute to the substorm current wedge (SCW), and how they evolve over time, using the THEMIS all-sky imagers (ASIs) and ground magnetometers. One type of events is dominated by a single large-scale wedge, with upward currents over the surge and broad downward currents poleward-eastward of the surge. The other type of events is a composite of large-scale wedge and wedgelets associated with streamers, with each wedgelet having comparable intensity to the large-scale wedge currents. Among 17 auroral substorms with wide ASI coverage, the composite current type is more frequent than the single large-scale wedge type. The dawn–dusk size of each wedgelet is ~ 600 km in the ionosphere (~ 3.2 R E in the magnetotail, comparable to the flow channel size). We suggest that substorms have more than one type of SCW, and the composite current type is more frequent.

【 授权许可】

Unknown