The Earth's magnetopause as a source and sink for equatorial nightside energetic charged particles

Klida, M. M.; Fritz, T. A.

doi:10.5194/angeo-27-4305-2009

Cited by 8 publications

(8 citation statements)

References 19 publications

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“…Calculations of the individual pitch angles for the data used in the analysis are shown in Fig. 1 and indicate that the range of pitch angles encountered at GPS altitudes is ∼20 • at L = 6, ∼10 • at L = 8, and <5 • at distances of L > 10, consistent with the results of Klida and Fritz (2009). Isotropy or quasi-isotropy deeper in the magnetotail allows the energetic electron population to be seen and measured at GPS altitudes in a similar way that the ion plasma sheet is seen and measured by low-altitude DMSP spacecraft (e.g.…”

Section: Analysis: a Density-temperature Description Of Electrons In supporting

confidence: 78%

Density and temperature of energetic electrons in the Earth's magnetotail derived from high-latitude GPS observations during the declining phase of the solar cycle

Denton

Cayton

2011

Ann. Geophys.

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Abstract. Single relativistic-Maxwellian fits are made to high-latitude GPS-satellite observations of energetic electrons for the period January 2006-November 2010; a constellation of 12 GPS space vehicles provides the observations. The derived fit parameters (for energies ∼0.1-1.0 MeV), in combination with field-line mapping on the nightside of the magnetosphere, provide a survey of the energetic electron density and temperature distribution in the magnetotail between McIlwain L-values of L = 6 and L = 22. Analysis reveals the characteristics of the density-temperature distribution of energetic electrons and its variation as a function of solar wind speed and the Kp index. The density-temperature characteristics of the magnetotail energetic electrons are very similar to those found in the outer electron radiation belt as measured at geosynchronous orbit. The energetic electron density in the magnetotail is much greater during increased geomagnetic activity and during fast solar wind. The total electron density in the magnetotail is found to be strongly correlated with solar wind speed and is at least a factor of two greater for high-speed solar wind (V SW = 500-1000 km s −1 ) compared to low-speed solar wind (V SW = 100-400 km s −1 ). These results have important implications for understanding (a) how the solar wind may modulate entry into the magnetosphere during fast and slow solar wind, and (b) if the magnetotail is a source or a sink for the outer electron radiation belt.

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Section: Analysis: a Density-temperature Description Of Electrons In supporting

confidence: 78%

Density and temperature of energetic electrons in the Earth's magnetotail derived from high-latitude GPS observations during the declining phase of the solar cycle

Denton

Cayton

2011

Ann. Geophys.

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“…We also note the presence of a trapped particle population in the 2-μT spin-perpendicular case, Figures 2e and 2f, above and below both poles (i.e., centered in the plane of the magnetic equator) and the presence of multiple shells of trapped (or potentially quasi-trapped) particles in the 5 μT case, Figure 2h. While beyond the scope of the current paper, an analysis of the population and stability of these trapped particle belts along with a comparison to analogous work at Earth (e.g., Klida & Fritz, 2009) and Mercury (e.g., Walsh et al, 2013;Yagi et al, 2017) is identified as a promising line of inquiry.…”

Section: Geophysical Research Lettersmentioning

confidence: 99%

The Lunar Paleo‐Magnetosphere: Implications for the Accumulation of Polar Volatile Deposits

Garrick‐Bethell

Poppe

Fatemi

2019

Geophysical Research Letters

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Analyses of lunar samples suggest the Moon once possessed a dynamo from ~4.25 Ga until perhaps as recently as 1 Ga, with surface field strengths between ~5 and 100 μT. While the exact timing, strength, and structure of these paleomagnetic fields are not precisely known, such relatively strong fields imply that the Moon also likely possessed a magnetosphere. Here, we present hybrid plasma simulations of the structure and morphology of the putative lunar “paleo‐magnetosphere” for varying surface field strengths and orientations, using ambient solar wind conditions representative of the early Sun. The presence of the paleo‐magnetosphere reduces total solar wind fluxes to the lunar surface overall yet, for a spin‐aligned dynamo, increases the relative solar wind flux to the lunar polar regions. In turn, the paleo‐magnetosphere may have altered the rate of volatile accretion to the Moon over its history.

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“…Further, the survey of ISEE‐1 observations supported the idea of the formation of butterfly pitch angle distributions over a wide energy range (20 keV–2 MeV) due to splitting of drift shells and magnetopause shadowing [ Fritz et al , ]. Similar results were obtained using the Polar observations of electron pitch angle distributions [ Klida and Fritz , , ]. However, Gannon et al [] demonstrated the dominance of electron butterfly distributions in the nightside and higher L shells for energies larger than 500 keV.…”

Section: Introductionmentioning

confidence: 64%

Butterfly pitch angle distribution of relativistic electrons in the outer radiation belt: Evidence of nonadiabatic scattering

et al. 2015

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In this paper we investigate the scattering of relativistic electrons in the nightside outer radiation belt (around the geostationary orbit). We consider the particular case of low geomagnetic activity (|D st | < 20 nT), quiet conditions in the solar wind, and absence of whistler wave emissions. For such conditions we find several events of Van Allen probe observations of butterfly pitch angle distributions of relativistic electrons (energies about 1-3 MeV). Many previous publications have described such pitch angle distributions over a wide energy range as due to the combined effect of outward radial diffusion and magnetopause shadowing. In this paper we discuss another mechanism that produces butterfly distributions over a limited range of electron energies. We suggest that such distributions can be shaped due to relativistic electron scattering in the equatorial plane of magnetic field lines that are locally deformed by currents of hot ions injected into the inner magnetosphere. Analytical estimates, test particle simulations, and observations of the AE index support this scenario. We conclude that even in the rather quiet magnetosphere, small scale (magnetic local time (MLT)-localized) injection of hot ions from the magnetotail can likely influence the relativistic electron scattering. Thus, observations of butterfly pitch angle distributions can serve as an indicator of magnetic field deformations in the nightside inner magnetosphere. We briefly discuss possible theoretical approaches and problems for modeling such nonadiabatic electron scattering.

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The Earth's magnetopause as a source and sink for equatorial nightside energetic charged particles

Cited by 8 publications

References 19 publications

Density and temperature of energetic electrons in the Earth's magnetotail derived from high-latitude GPS observations during the declining phase of the solar cycle

Density and temperature of energetic electrons in the Earth's magnetotail derived from high-latitude GPS observations during the declining phase of the solar cycle

The Lunar Paleo‐Magnetosphere: Implications for the Accumulation of Polar Volatile Deposits

Butterfly pitch angle distribution of relativistic electrons in the outer radiation belt: Evidence of nonadiabatic scattering

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