Calculation of auroral Bahner volume emission height profiles in the upper atmosphere

Sigernes, F.; Lorentzen, D. A.; Beehr, C.S.; Henriksen, K.

doi:10.1016/0021-9169(94)90199-6

Cited by 15 publications

(13 citation statements)

References 16 publications

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“…H α and H β lines observed by spectrophotometers have been reported for instance by Deehr et al (1998), Sigernes et al (1994) and Sigernes (1996). Little variation of the auroral brightness with latitude has been observed, except in the daytime polar cleft where profiles usually exhibit narrower shapes .…”

Section: Simon Et Al: Trans4: a New Coupled Electron/proton Transmentioning

confidence: 84%

“…As the 630.0 nm red line, routinely used to calibrate the spectra, is situated spectroscopically far away from the H α line it is sometimes better to recalibrate manually the spectrum around 6500Å through OH(6-1) rotational bands which show features at 6500, 6580 and 6600Å. The OH contribution has been subtracted from the H α line in the processed data by using a modelled OH spectrum based on Sigernes et al (2003) and described in Holmes et al (2007) 1 . Because of scattered sunlight approaching local noon, the H β profiles obtained were superimposed on a background containing significant Fraunhofer absorption near the H β rest wavelength.…”

Section: Esr and Optical Observationsmentioning

confidence: 99%

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

Simon¹,

Lilensten²,

Moen

et al. 2007

Ann. Geophys.

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Abstract. We present for the first time a numerical kinetic/fluid code for the ionosphere coupling proton and electron effects. It solves the fluid transport equations up to the eighth moment, and the kinetic equations for suprathermal particles. Its new feature is that for the latter, both electrons and protons are taken into account, while the preceding codes (TRANSCAR) only considered electrons. Thus it is now possible to compute in a single run the electron and ion densities due to proton precipitation. This code is successfully applied to a multi-instrumental data set recorded on 22 January 2004. We make use of measurements from the following set of instruments: the Defence Meteorological Satellite Program (DMSP) F-13 measures the precipitating particle fluxes, the EISCAT Svalbard Radar (ESR) measures the ionospheric parameters, the thermospheric oxygen lines are measured by an all-sky camera and the H α line is given by an Ebert-Fastie spectrometer located at Ny-Ålesund. We show that the code computes the H α spectral line profile with an excellent agreement with observations, providing some complementary information on the physical state of the atmosphere. We also show the relative effects of protons and electrons as to the electron densities. Computed electron densities are finally compared to the direct ESR measurements.

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Section: Simon Et Al: Trans4: a New Coupled Electron/proton Transmentioning

confidence: 84%

Section: Esr and Optical Observationsmentioning

confidence: 99%

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

Simon¹,

Lilensten²,

Moen

et al. 2007

Ann. Geophys.

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“…Since wavelength scanning records only a small segment of the line at a time, it is not practical to use a spectral resolution less than about 4Å for the weak hydrogen lines without resorting to long integration times. Fastie-Ebert scanning spectrophotometers were used to study hydrogen line profiles by Henriksen et al (1985), Sigernes et al (1994), Sigernes (1996), Lorentzen et al (1998), Deehr et al (1998), and Lummerzheim and Galand (2001). Application of CCD detectors to spectroscopy allowed for the simultaneous registration of all spectral elements of a line profile, resulting in a large sensitivity gain.…”

Section: Ground-based Observations Of Auroral Hydrogen Linesmentioning

confidence: 99%

High resolution measurements and modeling of auroral hydrogen emission line profiles

et al. 2003

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Abstract. Measurements in the visible wavelength range at high spectral resolution (1.3Å) have been made at Longyearbyen, Svalbard (15.8 E,78.2 N) during an interval of intense proton precipitation. The shape and Doppler shift of hydrogen Balmer beta line profiles have been compared with model line profiles, using as input ion energy spectra from almost coincident passes of the FAST and DMSP spacecraft. The comparison shows that the simulation contains the important physical processes that produce the profiles, and confirms that measured changes in the shape and peak wavelength of the hydrogen profiles are the result of changing energy input. This combination of high resolution measurements with modeling provides a method of estimating the incoming energy and changes in flux of precipitating protons over Svalbard, for given energy and pitch-angle distributions. Whereas for electron precipitation, information on the incident particles is derived from brightness and brightness ratios which require at least two spectral windows, for proton precipitation the Doppler profile of resulting hydrogen emission is directly related to the energy and energy flux of the incident energetic protons and can be used to gather information about the source region. As well as the expected Doppler shift to shorter wavelengths, the measured profiles have a significant red-shifted component, the result of upward flowing emitting hydrogen atoms.

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“…Recently Sigernes (1996) provided a magnetic-zenith pro®le of r a acquired with a half-meter Ebert-Fastie spectrometer with a resolution of 0.25 nm. Sigernes (1996) interpreted the red shift as due to instrumental broadening. However, no direct comparison between a model and the magnetic-zenith Doppler pro®le has been performed as yet.…”

Section: Comparison With Observationsmentioning

confidence: 99%

Proton transport model in the ionosphere. 2. Influence of magnetic mirroring and collisions on the angular redistribution in a proton beam

Galand

Lilensten²,

Kofman³

et al. 1998

Ann Geophysicae

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Abstract. We investigate the in¯uence of magnetic mirroring and elastic and inelastic scattering on the angular redistribution in a proton/hydrogen beam by using a transport code in comparison with observations. H-emission Doppler pro®les viewed in the magnetic zenith exhibit a red-shifted component which is indicative of upward¯uxes. In order to determine the origin of this red shift, we evaluate the in¯uence of two angular redistribution sources which are included in our proton/ hydrogen transport model. Even though it generates an upward¯ux, the redistribution due to magnetic mirroring eect is not sucient to explain the red shift. On the other hand, the collisional angular scattering induces a much more signi®cant red shift in the lower atmosphere. The red shift due to collisions is produced by`1 -keV protons and is so small as to require an instrumental bandwidth`0X2 nm. This explains the absence of measured upward proton/hydrogen¯uxes in the Proton I rocket data because no useable data concerning protons`1 keV are available. At the same time, our model agrees with measured ground-based H-emission Doppler pro®les and suggests that previously reported red shift observations were due mostly to instrumental bandwidth broadening of the pro®le. Our results suggest that Doppler pro®le measurements with higher spectral resolution may enable us to quantify better the angular scattering in proton aurora.

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Calculation of auroral Bahner volume emission height profiles in the upper atmosphere

Cited by 15 publications

References 16 publications

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

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

High resolution measurements and modeling of auroral hydrogen emission line profiles

Proton transport model in the ionosphere. 2. Influence of magnetic mirroring and collisions on the angular redistribution in a proton beam

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