On the nightglow polarisation for space weather exploration

Léo Bosse (1) , Jean Lilensten (1) , Nicolas Gillet (2) , Sylvain Rochat (1) , Alain Delboulbé (1) , Stephane Curaba (1) , Alain Roux (1) , Yves Magnard (1) , Magnar G. Johnsen (3) , Unni-Pia Løvhaug (4) , Pierre-Olivier Amblard (5) , Nicolas Le Bihan (5) , Maxime Nabon (1) , Hanane Marif (6) , Frédérique Auriol (7) , Camille Noûs (8)

1 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble
2 ISTerre - Institut des Sciences de la Terre
3 TGO - Tromsø Geophysical Observatory
4 UiT - The Arctic University of Norway [Tromsø, Norway]
5 GIPSA-GAIA - GIPSA Pôle Géométrie, Apprentissage, Information et Algorithmes
6 USTHB - Université des Sciences et de la Technologie Houari Boumediene = University of Sciences and Technology Houari Boumediene [Alger]
7 LOA - Laboratoire d’Optique Atmosphérique - UMR 8518
8 Laboratoire Cogitamus

We present here observations of the polarisation of four auroral lines in the auroral oval and in the polar cusp using a new ground polarimeter called Petit Cru. Our results confirm the already known polarisation of the red line, and show for the first time that the three other lines observed here (namely 557.7 nm, 391.4 nm and 427.8 nm) are polarised as well up to a few percent. We show that in several circumstances, this polarisation is linked to the local magnetic activity and to the state of the ionosphere through the electron density measured with EISCAT. However, we also show that the contribution of light pollution from nearby cities via scattering can not be ignored and can play an important role in polarisation measurements. This series of observations questions the geophysical origin of the polarisation. It also leaves open its relation to the magnetic field orientation and to the state of both the upper atmosphere and the troposphere.

Mots clés: polarisation; aurora

Domaines: Physique de l'espace [physics.space-ph]; Géophysique [physics.geo-ph]

Léo Bosse, Jean Lilensten, Nicolas Gillet, Sylvain Rochat, Alain Delboulbé, et al.. On the nightglow polarisation for space weather exploration. Journal of Space Weather and Space Climate, 2020, 10, pp.35. ⟨10.1051/swsc/2020036⟩. ⟨hal-02909104⟩