Estimating the location of the open-closed magnetic field line boundary from auroral images

Longden, N.; Chisham, G.; Freeman, M. P.; Abel, Gary; Sotirelis, T.

doi:10.5194/angeo-28-1659-2010

Cited by 42 publications

(154 citation statements)

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“…The BAS auroral boundaries are given every 2-3 min with a resolution of 1 h in magnetic local time. Additionally, the poleward auroral boundary has been calibrated by DMSP particle precipitation measurements (Longden et al, 2010). For our comparison, we set the UT difference between CHAMP and IM-AGE WIC observations to less than 2 min, and only good detections have been taken for comparison where the boundary difference between the two sets is less than 2 • in magnetic latitude.…”

Section: The Parameters In the Empirical Approachmentioning

confidence: 99%

“…Based on the energetic spectra measured by the special sensor for precipitating particles on the Defense Meteorological Satellite Program (DMSP), the auroral boundary index (ABI) model is provided to estimate the equatorward boundary of precipitating auroral electrons (Hardy et al, 2008). Boakes et al (2008) and Longden et al (2010) presented methods for an automatic detection of the auroral oval boundaries from the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite. The resulting 2.…”

Section: Introductionmentioning

confidence: 99%

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Determining the boundaries of the auroral oval from CHAMP field-aligned current signatures – Part 1

et al. 2014

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Abstract. In this paper we present the first statistical study on auroral oval boundaries derived from small-and mediumscale field-aligned currents (FACs, < 150 km). The dynamics of both the equatorward and poleward boundaries is deduced from 10 years of CHAMP (CHAllenging Minisatellite Payload) magnetic field data (August 2000-August 2010). The approach for detecting the boundaries from FACs works well under dark conditions. For a given activity level the boundaries form well-defined ellipses around the magnetic pole. The latitudes of the equatorward and poleward boundaries both depend, but in different ways, on magnetic activity. With increasing magnetic activity the equatorward boundary expands everywhere, while the poleward boundary shows on average no dependence on activity around midnight, which seems to be stationary at a value of about 72 • Mlat. Functional relations between the latitudes of the boundaries and different magnetic activity indices have been tested. Best results for a linear dependence are derived for both boundaries with the dayside merging electric field. The other indices, like the auroral electrojet (AE) and disturbance storm time (Dst) index, also provide good linear relations but with some caveats. Toward high activity a saturation of equatorwards expansion seems to set in. The locations of the auroral boundaries are practically independent of the level of the solar EUV flux and show no dependence on season.

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Section: The Parameters In the Empirical Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Determining the boundaries of the auroral oval from CHAMP field-aligned current signatures – Part 1

et al. 2014

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“…This more recent model is based on optical observations of the whole auroral oval by the IMAGE satellite. By means of an automatic detection scheme the auroral boundaries are detected (for details, see Longden et al, 2010). At intervals of 2 to 3 min, the complete oval is recovered.…”

Section: Validation Against the Bas Auroral Modelmentioning

confidence: 99%

“…This spacecraft was able to provide pictures of the whole oval every 2-3 min. Based on these data, Boakes et al (2008) and Longden et al (2010) developed techniques for an automatic detection of the auroral boundaries. A corresponding data set containing the boundary locations in the Northern Hemisphere for the years May 2000-October 2002 is available at the British Antarctic Survey (BAS) server.…”

Section: Introductionmentioning

confidence: 99%

An empirical model of the auroral oval derived from CHAMP field-aligned current signatures – Part 2

Xiong

Lühr

2014

Ann. Geophys.

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Abstract. In this paper we introduce a new model for the location of the auroral oval. The auroral boundaries are derived from small-and medium-scale field-aligned current (FAC) based on the high-resolution CHAMP (CHAllenging Minisatellite Payload) magnetic field observations during the years 2000-2010. The basic shape of the auroral oval is controlled by the dayside merging electric field, E m , and can be fitted well by ellipses at all levels of activity. All five ellipse parameters show a dependence on E m which can be described by quadratic functions. Optimal delay times for the merging electric field at the bow shock are 30 and 15 min for the equatorward and poleward boundaries, respectively. A comparison between our model and the British Antarctic Survey (BAS) auroral model derived from IMAGE (Imager for Magnetopause-to-Aurora Global Exploration) optical observations has been performed. There is good agreement between the two models regarding both boundaries, and the differences show a Gaussian distribution with a width of ±2 • in latitude. The difference of the equatorward boundary shows a local-time dependence, which is 1 • in latitude poleward in the morning sector and 1 • equatorward in the afternoon sector of the BAS model. We think the difference between the two models is caused by the appearance of auroral forms in connection with upward FACs. All information required for applying our auroral oval model (CH-Aurora-2014) is provided.

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“…However, particle detectors can sample only a tiny portion of the aurora at one instant. The OCB can be detected optically from satellite observations of the poleward boundary of the ultra-violet (UV) auroral oval [Longden et al, 2010], though such observations are not regularly available.…”

Section: Introductionmentioning

confidence: 99%

Time-spatial correspondence between Pi2 wave power and ultra-violet aurora bursts

Martines-Bedenko¹,

Пилипенко²,

Engebretson³

et al. 2017

Russ. J. Earth Sci.

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We have examined snapshots of overlaid ultra-violet (UV) auroral images from POLAR and IMAGE spacecraft and ULF wave power in the Pi2 frequency band (5-30 mHz). The latitudinal distribution of the Pi2 spectral power, as well as the position of the ionospheric electrojet, are inferred from the MACCS-CARISMA-MEASURE array of magnetic stations. A substorm develops as a series of "detonations", accompanied by an enhancement of auroral luminosity, intensification of the ionospheric currents, and a burst of Pi2 wave power. The epicenter of each detonation leaps during each activation poleward and westward. The latitudinal location of the auroral ionospheric westward electrojet and Pi2 power is found to be mainly associated with the poleward border of the auroral activation region. The result of case studies is supported by statistical superposed latitudinal distributions of the auroral intensity and Pi2 power. The found correspondence between the UV auroral oval and Pi2 power "epicenter" may help to identify a possible channel of Pi2 wave energy transmission from the magnetotail to the ground. KEYWORDS: ULF waves; Pi2 pulsations; substorm; auroral oval; ionospheric electrojet.

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Estimating the location of the open-closed magnetic field line boundary from auroral images

Cited by 42 publications

References 50 publications

Determining the boundaries of the auroral oval from CHAMP field-aligned current signatures – Part 1

Determining the boundaries of the auroral oval from CHAMP field-aligned current signatures – Part 1

An empirical model of the auroral oval derived from CHAMP field-aligned current signatures – Part 2

Time-spatial correspondence between Pi2 wave power and ultra-violet aurora bursts

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