Confirmation of the upper atmospheric emission polarisation and impact on space weather 

Leo Bosse - IPAG/CNRS, France; Jean Lilensten - IPAG/CNRS, France; Nicolas Gillet - ISTerre, France; Sylvain Rochat - IPAG/CNRS, France; Alain Delboulbe - IPAG/CNRS, France; Stephane Curaba - IPAG/CNRS, France; Alain Roux - IPAG/CNRS, France; Yves Magnard - IPAG/CNRS, France; Magnar G. Johnsen - Tromso Geophysical Observatory, Norway 

Session: Thermosphere-Ionosphere Interactions and Effects

Abstract

Our group confirmed in 2008, with a dedicated photopolarimeter, that the red line at 630 nm is polarised. Since then, several auroral emissions have also been shown to be polarised (Bosse et al., 2020). The impacts in term of space weather could be quite important, as this polarisation witnesses the variability in term of electron density and the ionospheric currents. However, one question remained in order to insure that the polarisation does not come from an out-of-line of sight emission via Rayleigh scattering. In order to check it, we solved a polarised radiative transfer equation that allows to take account of polluting ground sources or all sky camera images.

In this conference, we will show the first results of this study during a campaign held in February 2020 and March 2019, in Northern Norway. These results indicate that the emissions are at least partly polarised at the emission. We will discuss the first implications in term of atomic physics for the atomic oxygen and in term of space weather.