Relativistic electron losses related to EMIC waves during CIR and CME storms

Sandanger, Marit Irene; Søraas, F.; Sørbø, M.; Aarsnes, K.; Oksavik, K.; Evans, David S.

doi:10.1016/j.jastp.2008.07.006

Cited by 64 publications

(84 citation statements)

References 42 publications

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“…Most of the narrow events coincided with low-energy proton precipitation (30-80 keV). Such REP events have been associated with EMIC wave particle scattering in previous studies (e.g., Carson et al, 2012;Sandanger et al, 2009). It indicates that EMIC wave initiated REP might be highly localized in L shell (dL ≤ 0.5).…”

Section: Discussionsupporting

confidence: 57%

“…Yahnin et al (2016) attributed REP events on the nightside near the isotropy boundary to this kind of scattering. In a recent study by Smith et al (2016), it was argued that such a mechanism will precipitate both ring current protons and relativistic electrons and can often be confused with EMIC wave precipitation which has been identified by correlated REP and low-energy proton precipitation in the National Oceanic Atmospheric Administration Polar Orbiting Environmental Satellites (NOAA POES) Medium Energy Proton Electron Detector (MEPED) data (Carson et al, 2012;Sandanger et al, 2009). Most of these events were found to be located in the dusk-midnight-early morning sector and peaked during geomagnetically active times.…”

Section: 1002/2017ja024716mentioning

confidence: 99%

“…In previous studies such as Sandanger et al (2009) and Carson et al (2012), coincidence of relativistic precipitation with low-energy proton precipitation has been used as a proxy for EMIC wave particle interaction. As shown in Figures 4a and 4b, it was found that the highly L shell localized population of events coincided with low-energy proton precipitation indicating that REP associated with EMIC waves may be highly localized in L shell with dL ≤ 0.5.…”

Section: Single-satellite Measurements Of L Shell Extentmentioning

confidence: 99%

See 2 more Smart Citations

A Statistical Study of the Spatial Extent of Relativistic Electron Precipitation With Polar Orbiting Environmental Satellites

2017

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Relativistic electron precipitation (REP) in the atmosphere can contribute significantly to electron loss from the outer radiation belts. In order to estimate the contribution to this loss, it is important to estimate the spatial extent of the precipitation region. We observed REP with the zenith pointing (0°) Medium Energy Proton Electron Detector (MEPED) on board Polar Orbiting Environmental Satellites (POES), for 15 years (2000–2014) and used both single‐satellite and multisatellite measurements to estimate an average extent of the region of precipitation in L shell and magnetic local time (MLT). In the duration of 15 years (2000–2014), 31,035 REP events were found in this study. Events were found to split into two classes; one class of events coincided with proton precipitation in the P1 channel (30–80 keV), were located in the dusk and early morning sector, and were more localized in L shell (dL < 0.5), whereas the other class of events did not coincide with proton precipitation, were located mostly in the midnight sector, and were wider in L shell (dL ∼ 1–2.5). Both classes were highly localized in MLT (dMLT ≤ 3 h), occurring mostly during the declining phase of the solar cycle and geomagnetically active times. The events located in the midnight sector for both classes were found to be associated with tail magnetic field stretching which could be due to the fact that they tend to occur mostly during geomagnetically active times or could imply that precipitation is caused by current sheet scattering.

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Section: Discussionsupporting

confidence: 57%

Section: 1002/2017ja024716mentioning

confidence: 99%

Section: Single-satellite Measurements Of L Shell Extentmentioning

confidence: 99%

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A Statistical Study of the Spatial Extent of Relativistic Electron Precipitation With Polar Orbiting Environmental Satellites

2017

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“…The preferential occurrence of REP on the duskside has been observed by both satellites [Vampola, 1971;Green et al, 2004;Carson et al, 2013;Comess et al, 2013] and balloons [Foat et al, 1998;Lorentzen et al, 2000;Millan et al, 2002]. Coincident precipitation of electrons and ions has been reported by various satellite studies [Imhof et al, 1986;Bortnik et al, 2006;Sandanger et al, 2009;Carson et al, 2013]. Storm Probes (RBSP, now called "the Van Allen Probes") mission, provides the first balloon measurements of REP while comprehensive in situ measurements of both plasma waves and energetic particles are available .…”

Section: Introductionmentioning

confidence: 99%

Investigation of EMIC wave scattering as the cause for the BARREL 17 January 2013 relativistic electron precipitation event: A quantitative comparison of simulation with observations

Millan

Hudson

et al. 2014

Geophysical Research Letters

136

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Electromagnetic ion cyclotron (EMIC) waves were observed at multiple observatory locations for several hours on 17 January 2013. During the wave activity period, a duskside relativistic electron precipitation (REP) event was observed by one of the Balloon Array for Radiation belt Relativistic Electron Losses (BARREL) balloons and was magnetically mapped close to Geostationary Operational Environmental Satellite (GOES) 13. We simulate the relativistic electron pitch angle diffusion caused by gyroresonant interactions with EMIC waves using wave and particle data measured by multiple instruments on board GOES 13 and the Van Allen Probes. We show that the count rate, the energy distribution, and the time variation of the simulated precipitation all agree very well with the balloon observations, suggesting that EMIC wave scattering was likely the cause for the precipitation event. The event reported here is the first balloon REP event with closely conjugate EMIC wave observations, and our study employs the most detailed quantitative analysis on the link of EMIC waves with observed REP to date.

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“…Mechanisms resulting in atmospheric loss include pitch-angle scattering through wave particle interactions with magnetospheric plasma waves 13 and violation of the first adiabatic invariant due to highly stretched magnetotail fields (that is, those in which the field line curvature becomes comparable to the particle's gyro-radius 14 ). Several recent statistical studies have concluded that losses to the atmosphere are probably responsible for main phase 5,11 and recovery phase 15,16 electron loss during certain types of geomagnetic storms. However, the mainphase dropout results were inferred in those studies, with no clear observations showing that the primary loss was to the atmosphere.…”

mentioning

confidence: 99%

Explaining sudden losses of outer radiation belt electrons during geomagnetic storms

et al. 2012

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, can drive storm activity, but several outstanding questions remain concerning dropouts and the precise channels to which outer belt electrons are lost during these events. By analysing data collected at multiple altitudes by the THEMIS, GOES, and NOAA-POES spacecraft, we show that the sudden electron depletion observed during a recent storm's main phase is primarily a result of outward transport rather than loss to the atmosphere.Trapped radiation belt electrons undergo three characteristic types of motion: gyro-motion around magnetic field lines due to any velocity component perpendicular to the field, bounce-motion along field lines between magnetic mirror points due to any velocity component parallel to the field, and drift-motion around the Earth resulting from magnetic gradient and curvature drifts. Associated with each of these oscillatory motions are adiabatic invariants, which are conserved so long as electric and/or magnetic fields do not change on scales similar to those of the associated motions. The first invariant conserves the magnetic moment of the particle and is proportional to the perpendicular momentum squared divided by the local magnetic field strength; the second and third invariants conserve the integral of parallel momentum over one full bounce period and the magnetic flux through a particle's drift orbit, respectively. Magnetospheric changes on timescales much longer than electron drift periods are considered fully adiabatic, that is, they are fully reversible. Initially, it was thought that the observed flux dropouts were fully adiabatic changes in the system. Essentially, electrons moved radially outward (inward) during a storm's main (recovery) phase to conserve their third invariant as Earth's magnetic field was altered by the field produced by an enhanced (weakening) ring current 7,8 , which is a magnetospheric current system resulting from charge-dependent particle drift. As electrons moved radially outward (inward) in the field, their fluxes decreased (increased) for fixed energy as the first adiabatic invariant was also conserved. It was later shown that although this 'Dst effect' (after the disturbance storm time (Dst) geomagnetic index (Kp) used to indicate storm activity) does play a role in the flux dynamics, many flux dropouts do not return to the pre-storm flux level

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Relativistic electron losses related to EMIC waves during CIR and CME storms

Cited by 64 publications

References 42 publications

A Statistical Study of the Spatial Extent of Relativistic Electron Precipitation With Polar Orbiting Environmental Satellites

A Statistical Study of the Spatial Extent of Relativistic Electron Precipitation With Polar Orbiting Environmental Satellites

Investigation of EMIC wave scattering as the cause for the BARREL 17 January 2013 relativistic electron precipitation event: A quantitative comparison of simulation with observations

Explaining sudden losses of outer radiation belt electrons during geomagnetic storms

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