1IPAG, UMR5274, UJF-CNRS, BP 53, 38041 Saint-Martin d'Hères cedex 9, France
2Belgian Institute for Space Aeronomy, Ringlaan-3-Avenue Circulaire, 1180 Brussels, Belgium
3Department of Physics, University in Oslo, P.O.Box 1048, Blindern, 0316 Oslo, Norway
4UNIS, 9171 Longyearbyen, Norway
5RAL Space, Rutherford Appleton Laboratory, Harwell, Oxfordshire, OX11 0QX, UK
6Polish Space Research Center (Polish Academy of Sciences), Poland
7NASA LaRC-USA, USA
8University College London, UK
*now at: IRAP, CNRS/UPS, 9 avenue du Colonel Roche, BP 44346, 31028 Toulouse cedex 4, France
Received: 03 Dec 2010 – Revised: 07 Jun 2011 – Accepted: 14 Jun 2011 – Published: 22 Jun 2011
Abstract. The polarisation of the atomic oxygen red line in the Earth's thermosphere is observed in different configurations with respect to the magnetic field line at high latitude during several coordinated Incoherent Scatter radar/optical experiment campaigns. When pointing northward with a line-of-sight nearly perpendicular to the magnetic field, we show that, as expected, the polarisation is due to precipitated electrons with characteristic energies of a few hundreds of electron Volts. When pointing toward the zenith or southward with a line-of-sight more parallel to the magnetic field, we show that the polarisation practically disappears. This confirms experimentally the predictions deduced from the recent discovery of the red line polarisation. We show that the polarisation direction is parallel to the magnetic field line during geomagnetic activity intensification and that these results are in agreement with theoretical work.
Barthélémy, M., Lilensten, J., Pitout, F., Simon Wedlund, C., Thissen, R., Lorentzen, D., Sigernes, F., Moen, J., Gronoff, G., McCrea, I., Rothkael, H., Ménager, H., and Aruliah, A.: Polarisation in the auroral red line during coordinated EISCAT Svalbard Radar/optical experiments, Ann. Geophys., 29, 1101-1112, doi:10.5194/angeo-29-1101-2011, 2011.