The thermospheric auroral red line polarization: confirmation of detection and first quantitative analysis

Lilensten, Jean; Barthélemy, Mathieu; Amblard, Pierre‐Olivier; Lamy, H.; Wedlund, Cyril Simon; Bommier, V.; Moen, J.; Rothkaehl, Hanna; Eymard, Julien; Ribot, Jocelyn

doi:10.1051/swsc/2012023

Cited by 10 publications

(16 citation statements)

References 21 publications

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“…As shown in previous observations (Lilensten et al 2013a), the observed DoLP increases in the absence of aurora, which is consistent with our present case of an observed DoLP rather larger than the theoretical one.…”

Section: The Integration Limitssupporting

confidence: 94%

“…In the previous studies, we observed that it decreases when the conditions become more active (Lilensten et al 2013a). …”

Section: Spp Measurementsmentioning

confidence: 72%

“…It originates from the deactivation of the metastable O( 1 D) state. The polarisation of the thermospheric atomic oxygen red line at 630 nm was discovered by Lilensten et al (2008) with a dedicated Steerable Photo Polarimeter (SPP) equipped with a narrow interference filter, and later confirmed by subsequent observations (Lilensten et al 2013a). The Degree of Linear Polarisation (DoLP) observed has an average of 1-2%, with maximum values smaller than 10%.…”

Section: Introductionmentioning

confidence: 79%

“…In Lilensten et al (2013a), we removed the effect of the instrumental polarisation using the Mueller formalism (Stenflo 1994;Goldstein 2003;Martinez Herrero et al 2009). This data processing has been improved, so that we provide here the new development.…”

Section: Resultsmentioning

confidence: 99%

“…We checked that this new signal processing does not change the conclusions in Lilensten et al (2013a).…”

Section: Resultsmentioning

confidence: 99%

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The auroral red line polarisation: modelling and measurements

Lilensten

Bommier

Barthélemy

et al. 2015

J. Space Weather Space Clim.

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In this work, we model the polarisation of the auroral red line using the electron impact theory developed by Bommier et al. (2011). This theory enables the computation of the distribution of the Degree of Linear Polarisation (DoLP) as a function of height if the flux of precipitated electrons is provided as input. An electron transport code is used to infer the stationary electron flux at each altitude in the ionosphere as a function of energy and pitch angle. Using adequate cross-sections, the integral of this electron flux over energy and pitch angle provides an anisotropy parameter from which the theoretical local DoLP can be computed at each altitude. The modelled DoLP is then derived by integrating along the line-of-sight. Depending on the integration length, the modelled DoLP ranges between 0.6% for a very long integration length and 1.8% for a very short integration length localised around an altitude of 210 km. A parametric study is performed to check how the characteristics of the local DoLP (maximum value, altitude of the maximum, integrated height profile) vary. It is found that the polarisation is highly sensitive to the scattering function of the electrons, to the electron precipitation and to the geomagnetic activity. We compare these values to measured ones obtained during an observational campaign performed in February 2012 from Svalbard. The measured DoLP during the campaign was 1.9% ± 0.1%. The comparison between this value and the theoretical one is discussed. Discrepancies may be due to the poor constraint of the input parameters (thermosphere and ionosphere), to the fact that only electron precipitation is considered in this approach (and not proton precipitation for instance) and to the difficulty in constraining the exact width of the emission layer in the thermosphere.

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Section: The Integration Limitssupporting

confidence: 94%

“…In the previous studies, we observed that it decreases when the conditions become more active (Lilensten et al 2013a). …”

Section: Spp Measurementsmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 79%

Section: Resultsmentioning

confidence: 99%

“…We checked that this new signal processing does not change the conclusions in Lilensten et al (2013a).…”

Section: Resultsmentioning

confidence: 99%

See 3 more Smart Citations

The auroral red line polarisation: modelling and measurements

Lilensten

Bommier

Barthélemy

et al. 2015

J. Space Weather Space Clim.

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The thermospheric auroral red line Angle of Linear Polarization

et al. 2016

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The auroral red line at 630 nm is linearly polarized. Up to now, only its Degree of Linear Polarization had been studied. In this article, we examine for the first time the Angle of Linear Polarization (AoLP) and we compare the measurements to the apparent angle of the magnetic field at the location of the red line emission. We show that the AoLP is a tracer of the magnetic field configuration. This opens new perspectives, both in the frame of space weather and in the field of planetology.

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The grand aurorae borealis seen in Colombia in 1859

Cardenas¹,

Sánchez²,

Domínguez

2016

Advances in Space Research

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On Thursday, September 1, 1859, the British astronomer Richard Carrington, for the first time ever, observes a spectacular gleam of visible light on the surface of the solar disk, the photosphere. The Carrington Event, as it is nowadays known by scientists, occurred because of the high solar activity that had visible consequences on Earth, in particular reports of outstanding aurorae activity that amazed thousands of people in the western hemisphere during the dawn of September 2. The geomagnetic storm, generated by the solar-terrestrial event, had such a magnitude that the auroral oval expanded towards the equator, allowing low latitudes, like Panama's 9 • N, to catch a sight of the aurorae. An expedition was carried out to review several historical reports and books from the northern cities of Colombia allowed the identification of a narrative from Montería, Colombia (8 • 45' N), that describes phenomena resembling those of an aurorae borealis, such as fire-like lights, blazing and dazzling glares, and the appearance of an immense S-like shape in the sky. The very low latitude of the geomagnetic north pole in 1859, the lowest value in over half a millennia, is proposed to have allowed the observations of auroral events at locations closer to the equator, and supports the historical description found in Colombia. The finding of such chronicle represents one of the most complete descriptions of low-latitude sightings of aurorae caused by the Carrington Event.

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The thermospheric auroral red line polarization: confirmation of detection and first quantitative analysis

Cited by 10 publications

References 21 publications

The auroral red line polarisation: modelling and measurements

The auroral red line polarisation: modelling and measurements

The thermospheric auroral red line Angle of Linear Polarization

The grand aurorae borealis seen in Colombia in 1859

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