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High-resolution optical observations of neutral heating associated with the electrodynamics of an auroral arc

High-resolution optical observations of neutral heating associated with the electrodynamics of an auroral arc
High-resolution optical observations of neutral heating associated with the electrodynamics of an auroral arc
We present results that indicate the existence of two distinct neutral heating processes associated with a discrete auroral arc over Svalbard. Within the order of seconds, the thermospheric temperature profile displays a significant response to the arc on spatial scales smaller than 10 km. It is suggested that both heating signatures are associated with the electrodynamic system responsible for the formation of the arc. Pedersen currents produce a temperature increase of approximately 100 K, observed at altitudes between 80 and 160 kilometres, directly adjacent to the arc structure and on its poleward edge only. In contrast, field‐aligned currents produce a variable temperature increase, of approximately 50 K, which is observed within the arc itself and constrained to a narrow altitude range between 90 and 110 km. By utilizing a range of observations and new analysis methods we are able to measure the atmospheric neutral temperature profile, over auroral altitudes, at unprecedented temporal and spatial scales. The High Throughput Imaging Echelle Spectrograph records high‐resolution emission spectra of the aurora, which are then fitted with synthetic N2 spectra, generated with modeled N2 volume emission rate profiles and a library of trial temperature profiles. The N2 volume emission rate profiles are retrieved from the Southampton ionospheric model using precipitating particle energies and fluxes obtained from Auroral Structure and Kinetics and the EISCAT Svalbard Radar. The application of this technique allows us to produce a time series of neutral temperature profiles and measure the localized heating of the neutral atmosphere resulting from the electrodynamics of the arc.
2169-9402
Price, David, John
95c63aa4-5db1-4a35-8743-5acbced1a156
Whiter, Daniel
9a30d7b6-ea41-44fb-bd52-3ff1964eca5c
Chadney, Joshua
4209e45f-6092-4c9d-b46b-4b598269a0f3
Lanchester, Betty
e864533e-eea0-471f-a3f9-7c70c25be55b
Price, David, John
95c63aa4-5db1-4a35-8743-5acbced1a156
Whiter, Daniel
9a30d7b6-ea41-44fb-bd52-3ff1964eca5c
Chadney, Joshua
4209e45f-6092-4c9d-b46b-4b598269a0f3
Lanchester, Betty
e864533e-eea0-471f-a3f9-7c70c25be55b

Price, David, John, Whiter, Daniel, Chadney, Joshua and Lanchester, Betty (2019) High-resolution optical observations of neutral heating associated with the electrodynamics of an auroral arc. Journal of Geophysical Research: Space Physics. (doi:10.1029/2019JA027345).

Record type: Article

Abstract

We present results that indicate the existence of two distinct neutral heating processes associated with a discrete auroral arc over Svalbard. Within the order of seconds, the thermospheric temperature profile displays a significant response to the arc on spatial scales smaller than 10 km. It is suggested that both heating signatures are associated with the electrodynamic system responsible for the formation of the arc. Pedersen currents produce a temperature increase of approximately 100 K, observed at altitudes between 80 and 160 kilometres, directly adjacent to the arc structure and on its poleward edge only. In contrast, field‐aligned currents produce a variable temperature increase, of approximately 50 K, which is observed within the arc itself and constrained to a narrow altitude range between 90 and 110 km. By utilizing a range of observations and new analysis methods we are able to measure the atmospheric neutral temperature profile, over auroral altitudes, at unprecedented temporal and spatial scales. The High Throughput Imaging Echelle Spectrograph records high‐resolution emission spectra of the aurora, which are then fitted with synthetic N2 spectra, generated with modeled N2 volume emission rate profiles and a library of trial temperature profiles. The N2 volume emission rate profiles are retrieved from the Southampton ionospheric model using precipitating particle energies and fluxes obtained from Auroral Structure and Kinetics and the EISCAT Svalbard Radar. The application of this technique allows us to produce a time series of neutral temperature profiles and measure the localized heating of the neutral atmosphere resulting from the electrodynamics of the arc.

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Accepted/In Press date: 23 October 2019
e-pub ahead of print date: 6 November 2019

Identifiers

Local EPrints ID: 436319
URI: http://eprints.soton.ac.uk/id/eprint/436319
ISSN: 2169-9402
PURE UUID: 2fef7fd6-19d0-4fd1-bea0-dcdf1ea6c186
ORCID for Daniel Whiter: ORCID iD orcid.org/0000-0001-7130-232X
ORCID for Joshua Chadney: ORCID iD orcid.org/0000-0002-5174-2114

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Date deposited: 06 Dec 2019 17:30
Last modified: 07 Oct 2020 01:55

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