Electron excitation and auroral emission parameters

Judge, R. J. R.

doi:10.1016/0032-0633(72)90064-5

Cited by 28 publications

(7 citation statements)

References 23 publications

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“…The penetration height of the electron fluxes is determined by their energy and pitch-angle distribution. According to model calculations, electrons that have an initial pitch angle of 0 • (initial movement straight along the field line) and an energy of ∼ 100 eV penetrate down to altitudes of ∼ 300 km, and those with 5 keV down to ∼ 110 km (Judge, 1972). The lower boundary of penetration rises with increasing pitch angles.…”

Section: Introductionmentioning

confidence: 99%

Investigations of the auroral luminosity distribution and the dynamics of discrete auroral forms in a historical retrospective

Feldstein

Vorobjev

Zverev

et al. 2014

Hist. Geo Space. Sci.

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Section: Introductionmentioning

confidence: 99%

Investigations of the auroral luminosity distribution and the dynamics of discrete auroral forms in a historical retrospective

Feldstein

Vorobjev

Zverev

et al. 2014

Hist. Geo Space. Sci.

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“…Further, although in principle rules of thumb concerning the ratios of the intensities of various emissions can be used to estimate characteristic energies (Judge, 1972), this has not proven to be entirely practical for a number of reasons. Hence, although the optical emissions give a fairly clear picture of what is going on in terms of the distribution of energy density through the CPS and its various boundaries, we cannot use such observations to track the higher energy inner CPS and ring current particle populations that are so very important during substorms and storms.…”

Section: Introductionmentioning

confidence: 99%

Pc5 modulation of high energy electron precipitation: particle interaction regions and scattering efficiency

2005

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Abstract. Using the NORSTAR riometer and CANOPUS magnetometer arrays we have investigated the modulation of high energy electron precipitation by ULF waves in the Pc5 frequency band. We conducted two separate studies of Pc5 activity in the riometers. The first is an independent survey of three riometer stations in the Churchill line (one at each subauroral, auroral, and typical polar cap boundary latitudes) in which we identified all riometer Pc5-band pulsations over 11 years. All had a corresponding magnetometer pulsation implying that a magnetic pulsation, is a necessary condition for a riometer pulsation (in the Pc5 Band). We find seasonal and latitude dependencies in the occurrence of riometer pulsations. By a factor of two, there are more riometer pulsations occurring in the fall-winter than the spring-summer. At higher latitudes there is a tendency towards noon pulsations during the spring-summer, suggesting that the criteria for riometer pulsations is affected by the dipole tilt. Our second study was based on the previous magnetometer study of Baker et al. (2003). Using the database of Pc5 activity from that study we were able to select the riometer Pc5 pulsations which adhere to the strict Pc5 definition in the magnetometer. We find that roughly 95% of the riometer pulsations occurred in the morning sector compared to 70% in the magnetometer. Given a magnetometer pulsation at Gillam in the morning sector, there is a 70% chance of there being a corresponding riometer pulsation. The morning sector probabilities at Rankin (geomagnetic (PACE) latitude 74 • ) and Pinawa (61 • ) are 3% and 5%, respectively. These statistics suggest there is a localized region in the pre-noon magnetosphere where Pc5 band ULF activity can modulate high energy electron precipitation. We also find that riometer pulsations display a K p selection towards mid (i.e. 3-4) activity levels which mimics the product of the K p dependence of high-energy electron fluxes on the dawn side (from CRRES) and all magnetic Pc5 activity. A superposed epoch analysis revealed that the elevated electron flux needed to produce a riometer pulsation is Correspondence to: E. Spanswick (emma@phys.ucalgary.ca) most likely provided by substorm injections on the nightside. We also find that the amplitude of modulated precipitation correlates well with the product of the background absorption and the magnetic pulsation amplitude, again leading to the idea that a riometer pulsation needs both favorable magnetospheric electron flux conditions and large enough magnetic Pc5 wave activity. We further separate our pulsations into field line resonances (FLRs), and non-field line resonances (non-FLRs), as identified in the Baker et al. (2003) survey. We find that FLRs are more efficient at modulating particle precipitation, and non-FLRs display an amplitude cutoff below which they do not interact with the high energy electron population. We conclude that the high energy electron precipitation associated with Pc5 pulsations is caused by pitch angle scattering (diffusio...

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“…However, the average electron energy behavior allows one to estimate roughly the change in the auroral intensity I 6300 /I 5577 ratio. According to the Judge (1972) model, simultaneously with the solar wind plasma density increases, it is possible to expect the enhancement of this ratio from approximately 0.5 up to 2, which corresponds to the occurrence of red aurorae of rather significant intensity. These conclusions allow one to explain naturally the results received earlier by Liou et al (1998) and Khviusova and Leontyev (2002).…”

Section: Summary and Discussionmentioning

confidence: 99%

The solar wind plasma density control of night-time auroral particle precipitation

2004

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Abstract. DMSP F6 and F7 spacecraft observations of the average electron and ion energy, and energy fluxes in different night-time precipitation regions for the whole of 1986 were used to examine the precipitation features associated with solar wind density changes. It was found that during magnetic quietness (|AL|<100 nT), the enhancement of average ion fluxes was observed at least two times, along with the solar wind plasma density increase from 2 to 24 cm −3 . More pronounced was the ion flux enhancement that occurred in the b2i-b4s and b4s-b5 regions, which are approximately corresponding to the statistical auroral oval and map to the magnetospheric plasma sheet tailward of the isotropy boundary. The average ion energy decrease of about 2-4 kev was registered simultaneously with this ion flux enhancement. The results verify the occurrence of effective penetration of the solar wind plasma into the magnetospheric tail plasma sheet.

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Electron excitation and auroral emission parameters

Cited by 28 publications

References 23 publications

Investigations of the auroral luminosity distribution and the dynamics of discrete auroral forms in a historical retrospective

Investigations of the auroral luminosity distribution and the dynamics of discrete auroral forms in a historical retrospective

Pc5 modulation of high energy electron precipitation: particle interaction regions and scattering efficiency

The solar wind plasma density control of night-time auroral particle precipitation

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