TRANS4: a new coupled electron/proton transport code – comparison to observations above Svalbard using ESR, DMSP and optical measurements

Simon, Cyril; Lilensten, Jean; Moen, J.; Holmes, J. M.; Ogawa, Y.; Oksavik, K.; Denig, W. F.

doi:10.5194/angeo-25-661-2007

Cited by 24 publications

(28 citation statements)

References 69 publications

(66 reference statements)

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“…The recommendation of Laher and Gilmore (1990) for process (a), deduced from calculations, is in qualitative agreement with the laboratory measurements reported by Stone and Zipf (1974), later corrected by Zipf and Erdman (1985) and Doering and Gulcicek (1989); the uncertainty reaches 50 %. At 70 eV energy, process (b) is around 50 times less efficient than process (a).…”

Section: Ionospheric Response: Modelling the Optical Emissionssupporting

confidence: 75%

Polar cap arcs from the magnetosphere to the ionosphere: kinetic modelling and observations by Cluster and TIMED

et al. 2012

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Abstract. On 1 April 2004 the GUVI imager onboard the TIMED spacecraft spots an isolated and elongated polar cap arc. About 20 min later, the Cluster satellites detect an isolated upflowing ion beam above the polar cap. Cluster observations show that the ions are accelerated upward by a quasistationary electric field. The field-aligned potential drop is estimated to about 700 V and the upflowing ions are accompanied by a tenuous population of isotropic protons with a temperature of about 500 eV.The magnetic footpoints of the ion outflows observed by Cluster are situated in the prolongation of the polar cap arc observed by TIMED GUVI. The upflowing ion beam and the polar cap arc may be different signatures of the same phenomenon, as suggested by a recent statistical study of polar cap ion beams using Cluster data.We use Cluster observations at high altitude as input to a quasi-stationary magnetosphere-ionosphere (MI) coupling model. Using a Knight-type current-voltage relationship and the current continuity at the topside ionosphere, the model computes the energy spectrum of precipitating electrons at the top of the ionosphere corresponding to the generator electric field observed by Cluster. The MI coupling model provides a field-aligned potential drop in agreement with Cluster observations of upflowing ions and a spatial scale of the polar cap arc consistent with the optical observations by TIMED. The computed energy spectrum of the precipitating electrons is used as input to the Trans4 ionospheric transport code. This 1-D model, based on Boltzmann's kinetic formalism, takes into account ionospheric processes such as photoionization and electron/proton precipitation, and computes the optical and UV emissions due to precipitating electrons. The emission rates provided by the Trans4 code are compared to the optical observations by TIMED. They are similar in size and intensity. Data and modelling results are consistent with the scenario of quasi-static acceleration of electrons that generate a polar cap arc as they precipitate in the ionosphere. The detailed observations of the acceleration region by Cluster and the large scale image of the polar cap arc provided by TIMED are two different features of the same phenomenon. Combined together, they bring new light on the configuration of the high-latitude magnetosphere during prolonged periods of Northward IMF. Possible implications of the modelling results for optical observations of polar cap arcs are also discussed.

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Section: Ionospheric Response: Modelling the Optical Emissionssupporting

confidence: 75%

Polar cap arcs from the magnetosphere to the ionosphere: kinetic modelling and observations by Cluster and TIMED

et al. 2012

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“…A very detailed story of the discovery of the proton precipitations to the more recent observations and modelling can be found in Simon et al (2007) and will not be repeated here. The emission of the atomic oxygen red line in proton aurora is addressed in Lummerzheim et al (2001).…”

Section: Errors Sourcesmentioning

confidence: 99%

The auroral red line polarisation: modelling and measurements

Lilensten

Bommier

Barthélemy

et al. 2015

J. Space Weather Space Clim.

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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.

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“…For Venus we use VTS3 (Hedin et al, 1983) Gronoff et al (2007). For Mars, we use MTGCM (Bougher et al, 1999) with CO 2 , CO, N 2 , O 2 and O applied to the Viking/Mariner conditions (e.g., Simon et al, 2009). For Titan, we use the model of Müller-Wodarg et al (2000) and Cui et al (2009) with N 2 and CH 4 .…”

Section: Motivationmentioning

confidence: 99%

“…We use the TRANS-* family of codes adapted to Earth , Venus (Gronoff et al, , 2008, Mars (Simon et al, 2009), Titan (Lilensten et al, 2005;) and Jupiter (Ménager et al, 2010) as discussed below. The TRANS-* codes solve the 1-D kinetic transport Boltzmann equation for suprathermal electrons including updated elastic, ionisation, excitation and dissociative cross sections.…”

Section: Motivationmentioning

confidence: 99%

Comprehensive calculation of the energy per ion pair or <I>W</I> values for five major planetary upper atmospheres

et al. 2011

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Abstract. The mean energy W expended in a collision of electrons with atmospheric gases is a useful parameter for fast aeronomy computations. Computing this parameter in transport kinetic models with experimental values can tell us more about the number of processes that have to be taken into account and the uncertainties of the models. We present here computations for several atmospheric gases of planetological interest (CO 2 , CO, N 2 , O 2 , O, CH 4 , H, He) using a family of multi-stream kinetic transport codes. Results for complete atmospheres for Venus, Earth, Mars, Jupiter and Titan are also shown for the first time. A simple method is derived to calculate W of gas mixtures from single-component gases and is conclusively checked against the W values of these planetary atmospheres. Discrepancies between experimental and theoretical values show where improvements can be made in the measurement of excitation and dissociation cross-sections of specific neutral species, such as CO 2 and CO.

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TRANS4: a new coupled electron/proton transport code – comparison to observations above Svalbard using ESR, DMSP and optical measurements

Cited by 24 publications

References 69 publications

Polar cap arcs from the magnetosphere to the ionosphere: kinetic modelling and observations by Cluster and TIMED

Polar cap arcs from the magnetosphere to the ionosphere: kinetic modelling and observations by Cluster and TIMED

The auroral red line polarisation: modelling and measurements

Comprehensive calculation of the energy per ion pair or <I>W</I> values for five major planetary upper atmospheres

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TRANS4: a new coupled electron/proton transport code – comparison to observations above Svalbard using ESR, DMSP and optical measurements

Cited by 24 publications

References 69 publications

Polar cap arcs from the magnetosphere to the ionosphere: kinetic modelling and observations by Cluster and TIMED

Polar cap arcs from the magnetosphere to the ionosphere: kinetic modelling and observations by Cluster and TIMED

The auroral red line polarisation: modelling and measurements

Comprehensive calculation of the energy per ion pair or &lt;I&gt;W&lt;/I&gt; values for five major planetary upper atmospheres

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Product

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Comprehensive calculation of the energy per ion pair or <I>W</I> values for five major planetary upper atmospheres