Dayside magnetospheric and ionospheric responses to solar wind pressure increase: Multispacecraft and ground observations. Issue 11 (8th November 2016)

• Record Type: Journal Article
• Authors: Tian, A. M.; Shen, X. C.; Shi, Q. Q.; Tang, B. B.; Nowada, M.; Zong, Q. G.; Fu, S. Y.
• Is Part Of: Journal of geophysical research. Volume 121:Issue 11(2016:Nov.)
• Page Start: 10, 813
• Page End: 10, 830
• Publication Date: 2016-11-08
• Subjects: solar wind dynamic pressure pulse -- flow vortex -- ionospheric traveling convection flow; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2016JA022459
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: We provide in situ observations of the transient phenomena in the dayside magnetosphere during the preliminary impulse (PI) and main impulse (MI) event on 30 September 2008. The PI and MI geomagnetic signals are induced by twin traveling convection vortices with opposite polarities in the equivalent ionospheric currents due to a sudden increase of the solar wind dynamic pressure. The two PI‐associated ionospheric current vortices centered at ~07 magnetic local time (MLT), 67° magnetic latitude (MLAT) in the dawnside and ~14 MLT, 73°MLAT in the duskside, respectively. The dawnside MI current vortex centered at ~68° MLAT and 6 MLT, while the duskside vortex center was traveling poleward from ~67° MLAT to ~75° MLAT at a speed of ~5.6–7.4 km/s around 14 MLT. It is found that both dawnside PI‐ and MI‐related current vortices were azimuthally seen up to 4 MLT. Following the magnetosphere sudden impulse, a clockwise flow vortex with a radial scale larger than 3 RE, associated with positive field‐aligned current (FAC), was observed by Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft in the outer dayside magnetosphere. The flow vortex expanded and traveled tailward in the magnetosphere, also being reproduced with global MHD simulations. Based on both observation and simulation technique, we show that the MI‐related FACs are correlated with the large‐scale flow vortex. The PI FACs are partially provided by the mode conversion of fast mode waves into the Alfvén waves near the equatorial plane, while most of it may be generated at a higher‐latitude region in the magnetosphere. Key Points: Simultaneous observation on dayside magnetosphere vortex and ionosphere main pulse associated TCVs Global MHD simulation reproduced the observation Magnetospheric source of preliminary pulse is also discussed by observation and simulation