Horizontal electric fields from flow of auroral O&amp;lt;sup&amp;gt;+&amp;lt;/sup&amp;gt;(&amp;lt;sup&amp;gt;2&amp;lt;/sup&amp;gt;P) ions at sub-second temporal resolution

Tuttle, Sam Arthur; Lanchester, B. S.; Gustavsson, B.; Whiter, Daniel; Ivchenko, Nickolay; Fear, R. C.; Lester, M.

doi:10.5194/angeo-38-845-2020

Cited by 4 publications

(15 citation statements)

References 31 publications

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“…The main difference between the results presented in this paper and those in Tuttle et al (2020) is in the orientation of small-scale electric fields in relation to SuperDARN electric fields. The small-scale electric fields measured by Tuttle et al (2020) had a good agreement with SuperDARN electric fields, but auroral precipitation in that paper was instantaneous without an additional electromagnetic driver from precipitation. Therefore it is not surprising that the measured drift was in agreement with the convection over Svalbard at the time.…”

Section: Discussioncontrasting

confidence: 70%

“…The method of Tuttle et al. (2020) has been used in the present work to model the auroral emissions. Full details can be found in that paper, but a brief description is provided here.…”

Section: Methodsmentioning

confidence: 99%

“…In the present paper we have further expanded the technique of Tuttle et al. (2020) and Dahlgren et al. (2009) to estimate the small‐scale electric fields on either side of an auroral arc.…”

Section: Introductionmentioning

confidence: 99%

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Fine‐Scale Electric Fields and Joule Heating From Observations of the Aurora

et al. 2023

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Optical measurements from three selected wavelengths have been combined with modeling of emissions from an auroral event to estimate the magnitude and direction of small‐scale electric fields on either side of an auroral arc. The temporal resolution of the estimates is 0.1 s, which is much higher resolution than measurements from Super Dual Auroral Radar Network (SuperDARN) in the same region, with which we compare our estimates. Additionally, we have used the Scanning Doppler Imager instrument to measure the neutral wind during the event in order to calculate the height integrated Joule heating. Joule heating obtained from the small scale electric fields gives larger values (17 ± 11 and 6 ± 9 mWm−2 on average on each side of the arc) than the Joule heating obtained from more conventionally used SuperDARN data (5 mWm−2). This result is significant, because Joule heating will cause changes in the thermosphere from thermal expansion and thermal conductivity, and may also affect the acceleration of the neutral wind. Our result indicates that high spatial and temporal resolution electric fields may play an important role in the dynamics of the magnetosphere‐ionosphere‐thermosphere system.

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Section: Discussioncontrasting

confidence: 70%

“…The method of Tuttle et al. (2020) has been used in the present work to model the auroral emissions. Full details can be found in that paper, but a brief description is provided here.…”

Section: Methodsmentioning

confidence: 99%

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Fine‐Scale Electric Fields and Joule Heating From Observations of the Aurora

et al. 2023

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“…Previous work on electron and ion heating suggests that such a large electric field would produce temperatures much higher than those measured by ESR during event 1 (e.g. Bahcivan, 2006), but the spatial and temporal averaging required to measure electric fields using radar leads to an underestimate of the peak electric field value (Tuttle et al, 2020;Codrescu et al, 1995); a highly localised E-field magnitude of 300-400 mV m −1 may not be inconsistent with an observed electron temperature of about 2000 K. Farley-Buneman waves could be responsible for the electron heating through non-precipitation electron-neutral collisions (Saito et al, 2001), which may also produce the FAEs we observe through excitation of vibrational and rotational modes of N 2 .…”

Section: Farley-buneman Instabilitymentioning

confidence: 96%

“…Although this drift speed is very high, such an electric field is possible in a localised region next to an auroral arc (e.g. Lanchester et al, 1996;Tuttle et al, 2020;Marklund et al, 1994).…”

Section: Farley-buneman Instabilitymentioning

confidence: 99%

Fine-scale dynamics of fragmented aurora-like emissions

Whiter

Sundberg²,

Lanchester³

et al. 2021

Ann. Geophys.

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Abstract. Fragmented aurora-like emissions (FAEs) are small (few kilometres) optical structures which have been observed close to the poleward boundary of the aurora from the high-latitude location of Svalbard (magnetic latitude 75.3 ∘N). The FAEs are only visible in certain emissions, and their shape has no magnetic-field-aligned component, suggesting that they are not caused by energetic particle precipitation and are, therefore, not aurora in the normal sense of the word. The FAEs sometimes form wave-like structures parallel to an auroral arc, with regular spacing between each FAE. They drift at a constant speed and exhibit internal dynamics moving at a faster speed than the envelope structure. The formation mechanism of FAEs is currently unknown. We present an analysis of high-resolution optical observations of FAEs made during two separate events. Based on their appearance and dynamics, we make the assumption that the FAEs are a signature of a dispersive wave in the lower E-region ionosphere, co-located with enhanced electron and ion temperatures detected by incoherent scatter radar. Their drift speed (group speed) is found to be 580–700 m s−1, and the speed of their internal dynamics (phase speed) is found to be 2200–2500 m s−1, both for an assumed altitude of 100 km. The speeds are similar for both events which are observed during different auroral conditions. We consider two possible waves which could produce the FAEs, i.e. electrostatic ion cyclotron waves (EIC) and Farley–Buneman waves, and find that the observations could be consistent with either wave under certain assumptions. In the case of EIC waves, the FAEs must be located at an altitude above about 140 km, and our measured speeds scaled accordingly. In the case of Farley–Buneman waves a very strong electric field of about 365 mV m−1 is required to produce the observed speeds of the FAEs; such a strong electric field may be a requirement for FAEs to occur.

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In Praise of the Unexpected

Lanchester

2023

Perspectives of Earth and Spac

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There are many advantages to having an open mind in science; not being too set on a particular direction or outcome can be a good thing. For me, a career in Space Physics was completely serendipitous and certainly unexpected. Over the years I have been mentor and advisor to many students who have set their hearts on a career in Space Physics, and it has been a pleasure to be able to encourage and help them follow that ambition, while admiring their sense of purpose and forward planning. But my own experience was quite different—things just happened. So my advice is to welcome unexpected turns, and at the scientific level, to be ready to embrace a result that surprises, or maybe even disappoints. To quote from Mike Lockwood’s Frontiers article “In Praise of Mistakes” (Lockwood, 2022, https://doi.org/10.3389/fspas.2022.852798) which inspired this article’s title, “If one can recognize a mistake, it is often a path to unexpected progress.”

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Horizontal electric fields from flow of auroral O<sup>+</sup>(<sup>2</sup>P) ions at sub-second temporal resolution

Cited by 4 publications

References 31 publications

Fine‐Scale Electric Fields and Joule Heating From Observations of the Aurora

Fine‐Scale Electric Fields and Joule Heating From Observations of the Aurora

Fine-scale dynamics of fragmented aurora-like emissions

In Praise of the Unexpected

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