J. Space Weather Space Clim.
Volume 9, 2019
|Number of page(s)||8|
|Published online||16 July 2019|
Measurement of the polarisation in the auroral N2+ 427.8 nm band
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
2 Royal Belgian Institute for Space Aeronomy, Belgium
3 Tromsø Geophysical Observatory, UiT the Arctic University of Norway, Norway
4 USHB, Alger, Algeria
* Corresponding author: email@example.com
Accepted: 21 May 2019
In this paper, we provide for the first time polarisation measurements of the N+2 band at 427.8 nm performed with Premier Cru, a dedicated spectropolarimeter to investigate the polarisation of auroral emission lines between 400 and 700 nm. Details about the instrument, the observing conditions and the data analysis procedure are provided. Results obtained during three nights in March 2017 in Skibotn, Norway, indicate that the auroral blue line is polarised with a degree of linear polarisation of a few %. Due to weak Signal-to-Noise Ratios (SNR), these measurements still need to be taken with caution since none of the individual data set has a detection with a 3σ confidence level. However, results integrated over the entire observing period each night do show a 3σ detection but due to the long integration period, the origin of this polarisation cannot be linked to a specific type of aurora (diffuse vs structured arc) or specific ionospheric or geomagnetic conditions. These observations need to be confirmed with an improved design to increase the SNR and decrease the exposure time. When available, these improved measurements of the blue line polarisation will be important to better understand the physics of auroral processes at altitudes below 100 km where the N2+ emission occurs and possibly for space weather applications if the polarisation varies with ionospheric/geomagnetic conditions.
Key words: polarisation / aurora / space weather-ionosphere-instrumentation
© M. Barthelemy et al., Published by EDP Sciences 2015
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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