A stable auroral red (SAR) arc with multiple emission features

Mendillo, M.; Finan, Robert; Baumgardner, Jeffrey; Wroten, J.; Martinis, C. R.; Casillas, Marcus

doi:10.1002/2016ja023258

Cited by 14 publications

(18 citation statements)

References 36 publications

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“…We simply hypothesize that the red lines were a standard stable auroral red (SAR) arc, and that the other colors reflect "white pillars" due to field-aligned currents carried by precipitating electrons. In a similar recent example, Mendillo et al (2016) demonstrated a detailed analysis of the SAR arc, where several superimposed patches of green line emission were found during a magnetic storm. Enhancements in total electron content and radio wave scintillations at the patches support electron precipitation from the plasma sheet (Aarons, 1987).…”

Section: Possible Mechanisms Of Fan-shaped Auroramentioning

confidence: 88%

Fan-shaped aurora as seen from Japan during a great magnetic storm on February 11, 1958

Kataoka

Uchino

Fujiwara

et al. 2019

J. Space Weather Space Clim.

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During a great magnetic storm on Feb 11, 1958, a fan-shaped aurora was photographed at Memambetsu, Hokkaido, Japan – the first and oldest photograph record of auroras observed in Japan, accompanied by many hand-made drawings, thus, portraying a rare opportunity of coexistence between photograph images and hand-made drawings. In fact, the same portrayal reminds us of the great red aurora with fan-shaped white pillars observed during the 1872 and 1770 great magnetic storms. The hand-made sketches, photographs, and the spectral data revealed that the white pillars and red glow of the fan-shaped aurora were dominated by auroral green and red lines, respectively. From the analysis of newly digitized microfilm data and hand-made drawings, we found that the fan-shaped aurora appeared during the peak activity of magnetic storm and moved westward at 0.4 km/s at 400-km altitude at 38°–40° magnetic latitudes, which is consistent with the enhanced convection pattern in the middle latitude at storm time. Such a fan-shaped aurora can fundamentally characterize the middle-latitude evening-to-midnight auroras during great magnetic storms, which show the most destabilized transient appearance of the inner magnetosphere.

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Section: Possible Mechanisms Of Fan-shaped Auroramentioning

confidence: 88%

Fan-shaped aurora as seen from Japan during a great magnetic storm on February 11, 1958

Kataoka

Uchino

Fujiwara

et al. 2019

J. Space Weather Space Clim.

View full text Add to dashboard Cite

show abstract

“…This is in contrast to the rarer case of a SAR arc with structured patches of emission. Mendillo, Finan, et al (2016) showed unusual SAR arcs that included regions of enhanced 630.0-and 557.7-nm emission that did exhibit GPS phase fluctuations. These resulted from low energetic particle precipitation due to inward motion of ring current particles (Shiokawa et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

“…They showed not only very long lasting SAR arcs but also multiple patterns, zonal/horizontal inhomogeneity, and geomagnetic tilts of SAR arc. Mendillo, Finan, et al (2016) also described a rare kind of SAR arc that includes patches of green line emission induced by low energetic particle precipitation. Ongoing research deals with additional energy source mechanisms for SAR arcs, the influence of ring current evolution upon SAR arcs, and the roles of neutral composition and density.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Observations of SAR Arc and Its Ionospheric Response at Subauroral Conjugate Points (L ≃ 2.5) During the St. Patrick's Day Storm in 2015

et al. 2020

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During the St. Patrick's Day storm on 17 March 2015, an all-sky imager at King Sejong Station (KSS; geo: 62.2°S, 58.8°W; mag: 50.2°S) captured diffuse aurora and a stable auroral red (SAR) arc.Ground-based Global Positioning System observations were also simultaneously conducted at KSS, but there was no significant increase in the total electron content's rate-of-change index or the ionospheric scintillation indices around the SAR arc region. Auroral activities including a SAR arc were also detected by the all-sky imager at Millstone Hill Station (geo: 42.6°N, 71.4°W; mag: 52.5°N), which is magnetically conjugate to KSS. The total electron content's rate-of-change index map around Millstone Hill Station, too, indicates that the ionospheric irregularities occurred only near the diffuse aurora and not in the SAR arc. The northern SAR arc is broader than the southern one and also shows a multiplicity pattern, which may be due to latitude structure within the seasonally dependent midlatitude ionospheric trough. These conjugate observations, despite their hemispheric differences, validate the classical SAR arc mechanism of emission driven by heat conduction from the inner magnetosphere that does not generate small-scale ionospheric irregularities that can affect Global Positioning System radio signals. Previous studies of SAR arcs and very high frequency radiowave scintillations did show a positive correlation.

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“…They concluded that the SAR arc was caused by the inward movement of the ring current induced by storm-time substorms. Mendillo et al (2016) showed that a SAR arc developed zonally from east to west, and the arc was accompanied by a weak 557.7-nm patchy emission. Shiokawa et al (2009Shiokawa et al ( , 2017 and Takagi et al (2018) reported the detachment of SAR arcs from the auroral oval toward lower latitudes associated with substorm recovery.…”

Section: Introductionmentioning

confidence: 99%

Multi‐Event Analysis of Plasma and Field Variations in Source of Stable Auroral Red (SAR) Arcs in Inner Magnetosphere During Non‐Storm‐Time Substorms

et al. 2021

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Stable auroral red (SAR) arcs are optical events with dominant 630.0-nm emission caused by low-energy electron heat flux into the topside ionosphere from the inner magnetosphere. SAR arcs are observed at subauroral latitudes and often occur during the recovery phase of magnetic storms and substorms. Past studies concluded that these low-energy electrons were generated in the spatial overlap region between the outer plasmasphere and ring-current ions and suggested that Coulomb collisions between plasmaspheric electrons and ring-current ions are more feasible for the SAR-arc generation mechanism rather than Landau damping by electromagnetic ion cyclotron waves or kinetic Alfvén waves. This work studies three separate SAR-arc events with conjunctions, using all-sky imagers and inner magnetospheric satellites (Arase and Radiation Belt Storm Probes [RBSP]) during non-storm-time substorms on December 19, 2012 (event 1), January 17, 2015 (event 2), and November 4, 2019 (event 3). We evaluated for the first time the heat flux via Coulomb collision using full-energy-range ion data obtained by the satellites. The electron heat fluxes due to Coulomb collisions reached ∼10 9 eV/cm 2 /s for events 1 and 2, indicating that Coulomb collisions could have caused the SAR arcs. RBSP-A also observed local enhancements of 7-20-mHz electromagnetic wave power above the SAR arc in event 2. The heat flux for the freshly detached SAR arc in event 3 reached ∼10 8 eV/cm 2 /s, which is insufficient to have caused the SAR arc. In event 3, local flux enhancement of electrons (<200 eV) and various electromagnetic waves were observed, these are likely to have caused the freshly detached SAR arc.Plain Language Summary Stable auroral red (SAR) arcs are aurora with an optical red emission from oxygen atoms at latitudes slightly lower than the auroral oval and often occur during storm-time substorms. The oxygen excitation is caused by low-energy electrons transferred from the inner magnetosphere to the ionosphere. Past studies concluded that these low-energy electrons were generated INABA ET AL.

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A stable auroral red (SAR) arc with multiple emission features

Cited by 14 publications

References 36 publications

Fan-shaped aurora as seen from Japan during a great magnetic storm on February 11, 1958

Fan-shaped aurora as seen from Japan during a great magnetic storm on February 11, 1958

Simultaneous Observations of SAR Arc and Its Ionospheric Response at Subauroral Conjugate Points (L ≃ 2.5) During the St. Patrick's Day Storm in 2015

Multi‐Event Analysis of Plasma and Field Variations in Source of Stable Auroral Red (SAR) Arcs in Inner Magnetosphere During Non‐Storm‐Time Substorms

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