Modeling the OI 630.0 and 557.7 nm thermospheric dayglow during EISCAT‐WINDII coordinated measurements

Witasse, Olivier; Lilensten, Jean; Lathuillére, C.; Blelly, Pierre‐Louis

doi:10.1029/1999ja900260

Cited by 62 publications

(83 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The O 1 D production rate peaks at low altitude, around 110 km, whilst the red line emission peaks at much higher altitude, typically around 220 km. This difference is explained by the different losses through collisions with the neutral gas and the ambient electrons (Witasse et al 1998(Witasse et al , 1999Culot et al 2005). …”

Section: Red and Green Line Intensitiesmentioning

confidence: 99%

The auroral red line polarisation: modelling and measurements

Lilensten

Bommier

Barthélemy

et al. 2015

J. Space Weather Space Clim.

View full text Add to dashboard Cite

In this work, we model the polarisation of the auroral red line using the electron impact theory developed by Bommier et al. (2011). This theory enables the computation of the distribution of the Degree of Linear Polarisation (DoLP) as a function of height if the flux of precipitated electrons is provided as input. An electron transport code is used to infer the stationary electron flux at each altitude in the ionosphere as a function of energy and pitch angle. Using adequate cross-sections, the integral of this electron flux over energy and pitch angle provides an anisotropy parameter from which the theoretical local DoLP can be computed at each altitude. The modelled DoLP is then derived by integrating along the line-of-sight. Depending on the integration length, the modelled DoLP ranges between 0.6% for a very long integration length and 1.8% for a very short integration length localised around an altitude of 210 km. A parametric study is performed to check how the characteristics of the local DoLP (maximum value, altitude of the maximum, integrated height profile) vary. It is found that the polarisation is highly sensitive to the scattering function of the electrons, to the electron precipitation and to the geomagnetic activity. We compare these values to measured ones obtained during an observational campaign performed in February 2012 from Svalbard. The measured DoLP during the campaign was 1.9% ± 0.1%. The comparison between this value and the theoretical one is discussed. Discrepancies may be due to the poor constraint of the input parameters (thermosphere and ionosphere), to the fact that only electron precipitation is considered in this approach (and not proton precipitation for instance) and to the difficulty in constraining the exact width of the emission layer in the thermosphere.

show abstract

Section: Red and Green Line Intensitiesmentioning

confidence: 99%

The auroral red line polarisation: modelling and measurements

Lilensten

Bommier

Barthélemy

et al. 2015

J. Space Weather Space Clim.

View full text Add to dashboard Cite

show abstract

“…A dierence between the radar and the interferometers is that in the latter case, the observations are integrated over the ®eld of view, so that they take into account the emissions from above and below the crossing point. However, the peak altitude of the red line emission is relatively narrow, and the emission decreases rapidly above and below this maximum (Witasse et al, 1999). With such an experiment, if our hypothesis is correct, the oscillations should show up on the meridional component as well as on the zonal one, with a p/2 dierence of phase.…”

Section: Discussionmentioning

confidence: 99%

On the fast movements of the thermosphere: an interpretation

Lilensten

Amblard²

2001

Annales Geophysicae

Self Cite

View full text Add to dashboard Cite

Abstract. We examine the oscillations of the meridional neutral wind in the F region as seen by the EISCAT radar. We propose an interpretation in term of eddies (tourbillons) of typical size of a few tens to a few hundreds of kilometers. The observed rotation velocity is a few hundreds of meters per second. We suggest that the tourbillons are a common feature of thermospheric movements. We propose an optical experiment to check the validity of this assumption.

show abstract

“…A di erence between the radar and the interferometers is that in the latter case, the observations are integrated over the ®eld of view, so that they take into account the emissions from above and below the crossing point. However, the peak altitude of the red line emission is relatively narrow, and the emission decreases rapidly above and below this maximum (Witasse et al, 1999). With such an experiment, if our hypothesis is correct, the oscillations should show up on the meridional component as well as on the zonal one, with a p/2 di erence of phase.…”

Section: Discussionmentioning

confidence: 99%