Key Elements of Auroral Substorm Development and their Relationship to Recent Observations of Detached Sub-Auroral Phenomena Including STEVE-like Emissions

Journal Article · Fri Mar 26 00:00:00 EDT 2021 · Journal of Atmospheric and Solar-Terrestrial Physics

DOI:https://doi.org/10.1016/j.jastp.2021.105600· OSTI ID:1774478

Henderson, Michael Gerard ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Since Akasofu introduced the concept of the substorm in 1964, numerous refinements have been added to the phenomenological model of how auroral substorms develop. Here, we review several of the most important of these including; polar cap patches, intensifications of the Polar Activated Band (PAB) at the poleward edge of the bulge, the development of new arcs poleward, the generation of auroral streamers, the evolution of streamers into auroral torches and omega bands, the association of streamers with particle injection and BBF activity in the tail, and wedgelet-like magnetic perturbations on the ground. We also review the concept of “contact breakups” which are breakups that appear to be triggered by the arrival of streamer-like forms in the equatorward regions of the oval. Finally, we remind the community that the addition of detached sub-auroral emissions was made to the phenomenological picture of substorm develop in the late 1960s along with the concept of auroral streamers. Newer observations of detached sub-auroral (STEVE-like emissions) from the Viking/UVI and POLAR/VIS imagers are presented which confirm that they are east-west aligned bands of emission that separate away from the equatorward edge of the auroral oval in response to intensifications of the poleward edge of the bulge and subsequent streamer production. We propose a new model for the formation of detached sub-auroral (STEVE-like) emissions in which a non-linear growth of a SAPS-driven instability (e.g. like the shear-flow/ballooning instability) at the plasmapause results in the disruption of the boundary separating hot plasma sheet particle from the cold plasmaspheric plasma. It is proposed that the resulting intermixing of plasma populations leads to both the observed STEVE-like emissions and also provides a source of cold plasma on open drift paths that can feed the long-lived drainage plumes that have recently been discovered.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: LDRD; USDOE
• Grant/Contract Number: 89233218CNA000001
• OSTI ID: 1774478
• Alternate ID(s): OSTI ID: 1815082
• Report Number(s): LA-UR--21-22047
• Journal Information: Journal of Atmospheric and Solar-Terrestrial Physics, Journal Name: Journal of Atmospheric and Solar-Terrestrial Physics Vol. 218; ISSN 1364-6826
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

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