High‐resolution maps of the characteristic energy of precipitating auroral particles

Kosch, M. J.; Honary, F.; Pozo, C. F. del; Marple, S.; Hagfors, T.

doi:10.1029/2001ja900107

Cited by 25 publications

(35 citation statements)

References 53 publications

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“…(4). Note that, in keeping with Kosch et al (2001), points where the CNA was less than 0.07 dB have been excluded. The relationship is reasonably linear with a Pearson correlation coefficient of 0.8.…”

Section: The Methods Testedmentioning

confidence: 99%

“…The dataset used by Kosch et al (2001) gives values of and E 0 from the inversion of the EISCAT electron density profiles and the corresponding CNA data measured by the IRIS riometer (see Sect. 3.1).…”

Section: The Methods Testedmentioning

confidence: 99%

“…3.1). The fluxes used by Kosch et al (2001) are differential in pitch angle; to convert these to fluxes integral in pitch angle over the downward hemisphere as used here, the Kosch et al (2001) fluxes are multiplied by 2 π. Figure 1 presents the data and the leastsquares fit of Eq.…”

Section: The Methods Testedmentioning

confidence: 99%

“…Here, the method is extended to determine the flux for the case of a Maxwellian spectrum. Kosch et al (2001) made the assumption that the 38.2 MHz CNA (A in dB) is proportional to the square-root of the flux of precipitating electrons with energies exceeding 25 keV ( 25 ): A=k 25 . The differential number flux φ (in cm −2 s −1 keV −1 ) for a Maxwellian spectrum is…”

Section: The Methods Testedmentioning

confidence: 99%

“…2.3 "Energy map" method (K01) Kosch et al (2001) combined both CNA and the 557.7 nm column intensity to estimate the characteristic energy of electron precipitation. Their approach was to use measurements to calibrate a simple physical model of the CNA and optical intensity in terms of the characteristic energy for assumed Maxwellian or exponential precipitating electron spectra.…”

Section: The Methods Testedmentioning

confidence: 99%

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Comparison of methods to determine auroral ionospheric conductances using ground-based optical and riometer data

2008

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Abstract.Ground-based images of auroral optical emissions and cosmic radio noise absorption provide information on particle precipitation which enhances ionospheric conductances. Knowledge of this conductance field is important to understand the current systems associated with auroral features. Three methods of using ground-based optical and riometer data to estimate ionospheric conductances in the aurora are compared to conductances derived from incoherent scatter radar measurements. It is shown that a method using the 557.7 nm emission intensity alone gives the best results for the Pedersen conductance whilst a method using both this intensity and cosmic noise absorption is best for the Hall conductance. A method using cosmic noise absorption alone gives reasonable performance for the Hall conductance and the Hall/Pedersen conductance ratio, but performs poorly for the Pedersen conductance. It also appears to underestimate the Hall conductance significantly during times when softer precipitation is present, for example in discrete auroral arcs. There is some indication that the methods do not degrade noticeably for angles up to ∼20 • off magnetic zenith.

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Section: The Methods Testedmentioning

confidence: 99%

Section: The Methods Testedmentioning

confidence: 99%

Section: The Methods Testedmentioning

confidence: 99%

Section: The Methods Testedmentioning

confidence: 99%

Section: The Methods Testedmentioning

confidence: 99%

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Comparison of methods to determine auroral ionospheric conductances using ground-based optical and riometer data

2008

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Characterization of the energy‐dependent response of riometer absorption

et al. 2015

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Ground-based riometers provide an inexpensive means to continuously remote sense the precipitation of electrons in the dynamic auroral region of Earth's ionosphere. The energy-dependent relationship between riometer absorption and precipitating electrons is thus of great importance for understanding the loss of electrons from the Earth's magnetosphere. In this study, statistical and event-based analyses are applied to determine the energy of electrons to which riometers chiefly respond. Time-lagged correlation analysis of trapped to precipitating fluxes shows that daily averaged absorption best correlates with ∼60 keV trapped electron flux at zero-time lag, although large variability is observed across different phases of the solar cycle. High-time resolution statistical cross-correlation analysis between signatures observed by riometer stations, and assuming electron motion due to gradient and curvature drift, results in inferred energies of 10-100 keV, with a clear maximum in occurrence for 40-60 keV electrons. One event is considered in detail utilizing riometer absorption signatures obtained from several stations. The mean inferred energies for the initial rise time and peak of the absorption after correction for electric field effects were ∼70 keV and ∼60 keV, respectively. The analyses presented provide a means to characterize the energy of electrons to which riometers are responding in both a statistical sense and during the evolution of individual events.

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Simultaneous Measurements of Substorm‐Related Electron Energization in the Ionosphere and the Plasma Sheet

et al. 2017

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On 26 March 2008, simultaneous measurements of a large substorm were made using the Poker Flat Incoherent Scatter Radar, Time History of Events and Macroscale Interactions during Substorm (THEMIS) spacecraft, and all sky cameras. After the onset, electron precipitation reached energies ≳100 keV leading to intense D region ionization. Identifying the source of energetic precipitation has been a challenge because of lack of quantitative and magnetically conjugate measurements of loss cone electrons. In this study, we use the maximum entropy inversion technique to invert altitude profiles of ionization measured by the radar to estimate the loss cone energy spectra of primary electrons. By comparing them with magnetically conjugate measurements from THEMIS‐D spacecraft in the nightside plasma sheet, we constrain the source location and acceleration mechanism of precipitating electrons of different energy ranges. Our analysis suggests that the observed electrons ≳100 keV are a result of pitch angle scattering of electrons originating from or tailward of the inner plasma sheet at ~9RE, possibly through interaction with electromagnetic ion cyclotron waves. The electrons of energy 10–100 keV are produced by pitch angle scattering due to a potential drop of ≲10 kV in the auroral acceleration region (AAR) as well as wave–particle interactions in and tailward of the AAR. This work demonstrates the utility of magnetically conjugate ground‐ and space‐based measurements in constraining the source of energetic electron precipitation. Unlike in situ spacecraft measurements, ground‐based incoherent scatter radars combined with an appropriate inversion technique can be used to provide remote and continuous‐time estimates of loss cone electrons in the plasma sheet.

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High‐resolution maps of the characteristic energy of precipitating auroral particles

Cited by 25 publications

References 53 publications

Comparison of methods to determine auroral ionospheric conductances using ground-based optical and riometer data

Comparison of methods to determine auroral ionospheric conductances using ground-based optical and riometer data

Characterization of the energy‐dependent response of riometer absorption

Simultaneous Measurements of Substorm‐Related Electron Energization in the Ionosphere and the Plasma Sheet

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