On the nightglow polarisation: a new window for space weather - - PowerPoint PPT Presentation

▶
on the nightglow polarisation a new window for space
SMART_READER_LITE
LIVE PREVIEW

On the nightglow polarisation: a new window for space weather - - PowerPoint PPT Presentation

Sep 24, 2022 22 likes •122 views

ESWW16 18/11/2019 Lo Bosse 1 , Jean Lilensten 1,5 , Nicolas Gillet 3 , Sylvain Rochat 1 , Alain Delboulb 1 , Stephane Curaba 1 , Alain Roux 1 , Yves Magnard 1 , Magnar G. Johnsen 4 , Unni-Pia Lvhaug 6 , Pierre-Olivier Amblard 2 , Nicolas le

slide-1
SLIDE 1

On the nightglow polarisation: a new window for space weather observations?

Léo Bosse1 , Jean Lilensten1,5, Nicolas Gillet3, Sylvain Rochat1, Alain Delboulbé1, Stephane Curaba1, Alain Roux1, Yves Magnard1, Magnar G. Johnsen4, Unni-Pia Løvhaug6, Pierre-Olivier Amblard2, Nicolas le Bihan2 et Maxime Nabon1

(1) Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) CNRS – UGA, France (2) GIPSA-lab, Dept. Images and Signals, UMR CNRS, France (3) IsTerre, CNRS – UGA, France (4) Tromsø Geophysical Observatory, University of Tromsø, Tromsø, Norway (5) Honorary astronomer at Royal Observatory of Belgium, Brussels (6) Department of Physics and Technology, University of Tromsø, Tromsø, Norway

ESWW16 18/11/2019

slide-2
SLIDE 2

18/11/2019 Leo.Bosse@univ-grenoble-alpes.fr 2

Electrons entry in the upper atmosphere

  • Electromagnetic fields

guiding electrons

  • Excitation of upper

atmosphere

  • Radiative desexcitation
slide-3
SLIDE 3

18/11/2019 Leo.Bosse@univ-grenoble-alpes.fr 3

Transitions

Atomic oxygen:

  • Red (630 nm) ~200km
  • Green (557.7 nm)

~110km Nitrogen N2

+:

  • Blue (427.8 nm) ~85km
  • Purple (391.4 nm)

~85km

Credits: NASA

slide-4
SLIDE 4

18/11/2019 Leo.Bosse@univ-grenoble-alpes.fr 4

Polarization processes

  • Aurora polarization (Bommier et al., 2011)

parallel to electron’s incoming direction (theoretically possible in the red, not in the green)

  • Rayleigh scattering

in lower atmosphere

slide-5
SLIDE 5

18/11/2019 Leo.Bosse@univ-grenoble-alpes.fr 5

Interests and applications

  • Discovery of auroral emissions polarization

(Lilensten et al. 2008, 2013, 2015, 2016)

  • Indirect and real-time monitoring of

electromagnetic field in the transition region between internal and external magnetic field

– Satellites too high – Balloons too low

slide-6
SLIDE 6

18/11/2019 Leo.Bosse@univ-grenoble-alpes.fr 6

Instrument: Petit Cru

Photomultiplier

Incoming light Rotating polarizing filter Color filter

Intensity time series

Time

slide-7
SLIDE 7

18/11/2019 Leo.Bosse@univ-grenoble-alpes.fr 7

Q1: Where does it come from?

slide-8
SLIDE 8

18/11/2019 Leo.Bosse@univ-grenoble-alpes.fr 8

Q2: How is the green line polarized?

slide-9
SLIDE 9

18/11/2019 Leo.Bosse@univ-grenoble-alpes.fr 9

Conclusion

  • The night sky is polarized
  • 2 possible sources of polarization:

– Upper atmosphere: Aurora / night-glow – Lower atmosphere:

  • Rayleigh scattering: From aurora / city lights
  • Aerosols
  • New space weather proxy once disentangled
  • Radiative transfer model and controlled environment to

help us discriminate

slide-10
SLIDE 10

18/11/2019 Leo.Bosse@univ-grenoble-alpes.fr 10

Q3: Can we model RS contribution?

N E S O N