Identifying STEVE's Magnetospheric Driver Using Conjugate Observations in the Magnetosphere and on the Ground

Xiangning Chu, David Malaspina, Bea Gallardo-Lacourt, Jun Liang, Laila Andersson, Qianli Ma, Anton Artemyev, Jiang Liu, Robert E. Ergun, Scott Thaller, Hassanali Akbari, Hong Zhao, Brian Larsen, Geoffrey Reeves, John Wygant, Aaron Breneman, Sheng Tian, Martin Connors, Eric Donovan, William ArcherElizabeth A. MacDonald

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The magnetospheric driver of strong thermal emission velocity enhancement (STEVE) is investigated using conjugate observations when Van Allen Probes' footprint directly crossed both STEVE and stable red aurora (SAR) arc. In the ionosphere, STEVE is associated with subauroral ion drift features, including electron temperature peak, density gradient, and westward ion flow. The SAR arc at lower latitudes corresponds to regions inside the plasmapause with isotropic plasma heating, which causes redline-only SAR emission via heat conduction. STEVE corresponds to the sharp plasmapause boundary containing quasi-static subauroral ion drift electric field and parallel-accelerated electrons by kinetic Alfvén waves. These parallel electrons could precipitate and be accelerated via auroral acceleration processes powered by Alfvén waves propagating along the magnetic field with the plasmapause as a waveguide. The electron precipitation, superimposed on the heat conduction, could explain multiwavelength continuous STEVE emission. The green picket-fence emissions are likely optical manifestations of electron precipitation associated with wave structures traveling along the plasmapause.

Original languageEnglish (US)
Pages (from-to)12665-12674
Number of pages10
JournalGeophysical Research Letters
Volume46
Issue number22
DOIs
StatePublished - Nov 28 2019

Bibliographical note

Funding Information:
This work was supported by NASA Awards NNX17AB81G and NAS5-01072. The authors thank Robert McPherron, Jacob Bortnik, and Jinxing Li for helpful discussions. The authors thank Colin Chatfield and Neil Zeller for their STEVE photographs, Johnathan Burchill for assistance in calibrating the Swarm ion drift measurement, and Ian Schofield for AUGSO data. We acknowledge NSSDC Omniweb for geomagnetic activity indices (spdf.gsfc.nasa.gov). The authors thank the Van Allen Probes team, especially the EFW, EMFISIS, and ECT teams for their support (rbspgway.jhuapl.edu/data_instrumentationSOC). Swarm data are available online (swarm-diss.eo.esa.int). THEMIS and REGO ASIs, FESO, and AUGSO data are available online (themis.ssl.berkeley.edu website, data.phys.ucalgary.ca website, and http://autumn.athabascau.ca/publication_data/2019GL082789RRRR). Data processing was done using SPEDAS (Angelopoulos et al.,).

Funding Information:
spdf.gsfc.nasa.gov rbspgway.jhuapl.edu/data_instrumentationSOC swarm‐diss.eo.esa.int themis.ssl.berkeley.edu data.phys.ucalgary.ca ). This work was supported by NASA Awards NNX17AB81G and NAS5‐01072. The authors thank Robert McPherron, Jacob Bortnik, and Jinxing Li for helpful discussions. The authors thank Colin Chatfield and Neil Zeller for their STEVE photographs, Johnathan Burchill for assistance in calibrating the Swarm ion drift measurement, and Ian Schofield for AUGSO data. We acknowledge NSSDC Omniweb for geomagnetic activity indices ( ). The authors thank the Van Allen Probes team, especially the EFW, EMFISIS, and ECT teams for their support ( ). Swarm data are available online ( ). THEMIS and REGO ASIs, FESO, and AUGSO data are available online ( website, website, and http://autumn.athabascau.ca/publication_data/2019GL082789RRRR ). Data processing was done using SPEDAS (Angelopoulos et al.,

Publisher Copyright:
©2019. American Geophysical Union. All Rights Reserved.

Keywords

  • STEVE
  • aurora
  • kinetic Alfven wave
  • plasmapause
  • stable red auroral arc
  • subauroral ion drift

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