Calculation of Last Closed Drift Shells for the 2013 GEM Radiation Belt Challenge Events

Albert, J. M.; Selesnick, R. S.; Morley, S.; Henderson, M. G.; Kellerman, Adam

doi:10.1029/2018ja025991

Cited by 34 publications

(66 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Albert et al. (2018) studied several codes to calculate the LCDS in different magnetic field models for four different disturbed periods and concluded that, nevertheless, they produce seemingly reasonable and similar results. Moreover, it must be underlined that magnetic field models, such as TS07, are empirical approximations of the real field during geomagnetic disturbances.…”

Section: Discussionmentioning

confidence: 99%

Quantifying the Effects of EMIC Wave Scattering and Magnetopause Shadowing in the Outer Electron Radiation Belt by Means of Data Assimilation

et al. 2020

View full text Add to dashboard Cite

In this study we investigate two distinct loss mechanisms responsible for the rapid dropouts of radiation belt electrons by assimilating data from Van Allen Probes A and B and Geostationary Operational Environmental Satellites (GOES) 13 and 15 into a 3‐D diffusion model. In particular, we examine the respective contribution of electromagnetic ion cyclotron (EMIC) wave scattering and magnetopause shadowing for values of the first adiabatic invariant μ ranging from 300 to 3,000 MeV G−1. We inspect the innovation vector and perform a statistical analysis to quantitatively assess the effect of both processes as a function of various geomagnetic indices, solar wind parameters, and radial distance from the Earth. Our results are in agreement with previous studies that demonstrated the energy dependence of these two mechanisms. We show that EMIC wave scattering tends to dominate loss at lower L shells, and it may amount to between 10%/hr and 30%/hr of the maximum value of phase space density (PSD) over all L shells for fixed first and second adiabatic invariants. On the other hand, magnetopause shadowing is found to deplete electrons across all energies, mostly at higher L shells, resulting in loss from 50%/hr to 70%/hr of the maximum PSD. Nevertheless, during times of enhanced geomagnetic activity, both processes can operate beyond such location and encompass the entire outer radiation belt.

show abstract

Section: Discussionmentioning

confidence: 99%

Quantifying the Effects of EMIC Wave Scattering and Magnetopause Shadowing in the Outer Electron Radiation Belt by Means of Data Assimilation

et al. 2020

View full text Add to dashboard Cite

show abstract

“…This is understandable. On the one hand, the L * corresponding to the last closed drift shell is lager at larger K due to drift shell splitting (Albert et al, ; Roederer & Zhang, ). On the other hand, electrons drift period, which is a proxy of the lifetime for magnetopause‐loss (e.g., Tu et al, ), is longer for electrons of larger K .…”

Section: Discussionmentioning

confidence: 99%

On Phase Space Density and Its Radial Gradient of Outer Radiation Belt Seed Electrons: MMS/FEEPS Observations

2020

View full text Add to dashboard Cite

Electrons of ∼10 2 keV in the inner magnetosphere are suggested potentially to be the "seeds" of outer radiation belt electrons. Investigations into them could shed light on the origination of the outer radiation belt. Here we conduct statistics on seed electron phase space density (PSD) and its radial gradient, using 2-year data obtained by Fly's Eye Energetic Particle Spectrometer (FEEPS) onboard Magnetospheric Multiscale (MMS). The radial distributions of the PSD are and K dependent, and azimuthally asymmetric. In the nightside, as L * increases, PSD at lower always increases, while PSD at higher first increases and then decreases. In contrast, in the noonside, PSD first increases and then decreases at all covered . Crossover , defined as at which PSD radial gradient is equal to 0, is identified from the statistics. It relatively stays a constant of ∼300 MeV/G inside L * ∼ 6, but decreases as L * increases outside L * ∼ 6. Crossover is larger in the nightside than in the noonside and is larger at smaller K. The radial structures of seed electron PSD should be taken into account when considering the dynamics of the outer radiation belt.

show abstract

“…Outer zone electron dropout events are a common feature of geomagnetic storms, particularly at higher L shells (e.g., Green Onsager et al, 2002;Shprits et al, 2006;Su et al, 2017;Turner, Angelopoulos, Morley, et al, 2014;Ukhorskiy et al, 2015;Xiang et al, 2017). Rapid radial loss is observed with CME shock-driven storms (Hudson et al, 2014) and well correlated with the last closed drift shell during strong magnetopause compression (Albert et al, 2018;Olifer et al, 2018). Drift shell splitting is enhanced during such events wherein electrons near 90°pitch angle move to larger radial distance on the dayside conserving their first adiabatic invariant (Roederer, 1967(Roederer, , 1970, and may be preferentially lost to the magnetopause.…”

Section: Radial Lossmentioning

confidence: 99%

Earth's Van Allen Radiation Belts: From Discovery to the Van Allen Probes Era

2019

View full text Add to dashboard Cite

Discovery of the Earth's Van Allen radiation belts by instruments flown on Explorer 1 in 1958 was the first major discovery of the Space Age. The observation of distinct inner and outer zones of trapped megaelectron volt (MeV) particles, primarily protons at low altitude and electrons at high altitude, led to early models for source and loss mechanisms including Cosmic Ray Albedo Neutron Decay for inner zone protons, radial diffusion for outer zone electrons and loss to the atmosphere due to pitch angle scattering. This scattering lowers the mirror altitude for particles in their bounce motion parallel to the Earth's magnetic field until they suffer collisional loss. A view of the belts as quasi‐static inner and outer zones of energetic particles with different sources was modified by observations made during the Solar Cycle 22 maximum in solar activity over 1989–1991. The dynamic variability of outer zone electrons was measured by the Combined Radiation Release and Effects Satellite launched in July 1990. This variability is caused by distinct types of heliospheric structure that vary with the solar cycle. The launch of the twin Van Allen Probes in August 2012 has provided much longer and more comprehensive measurements during the declining phase of Solar Cycle 24. Roughly half of moderate geomagnetic storms, determined by intensity of the ring current carried mostly by protons at hundreds of kiloelectron volts, produce an increase in trapped relativistic electron flux in the outer zone. Mechanisms for accelerating electrons of hundreds of electron volts stored in the tail region of the magnetosphere to MeVenergies in the trapping region are described in this review: prompt and diffusive radial transport and local acceleration driven by magnetospheric waves. Such waves also produce pitch angle scattering loss, as does outward radial transport, enhanced when the magnetosphere is compressed. While quasilinear simulations have been used to successfully reproduce many essential features of the radiation belt particle dynamics, nonlinear wave‐particle interactions are found to be potentially important for causing more rapid particle acceleration or precipitation. The findings on the fundamental physics of the Van Allen radiation belts potentially provide insights into understanding energetic particle dynamics at other magnetized planets in the solar system, exoplanets throughout the universe, and in astrophysical and laboratory plasmas. Computational radiation belt models have improved dramatically, particularly in the Van Allen Probes era, and assimilative forecasting of the state of the radiation belts has become more feasible. Moreover, machine learning techniques have been developed to specify and predict the state of the Van Allen radiation belts. Given the potential Space Weather impact of radiation belt variability on technological systems, these new radiation belt models are expected to play a critical role in our technological society in the future as much as meteorological models do today.

show abstract

Calculation of Last Closed Drift Shells for the 2013 GEM Radiation Belt Challenge Events

Cited by 34 publications

References 47 publications

Quantifying the Effects of EMIC Wave Scattering and Magnetopause Shadowing in the Outer Electron Radiation Belt by Means of Data Assimilation

Quantifying the Effects of EMIC Wave Scattering and Magnetopause Shadowing in the Outer Electron Radiation Belt by Means of Data Assimilation

On Phase Space Density and Its Radial Gradient of Outer Radiation Belt Seed Electrons: MMS/FEEPS Observations

Earth's Van Allen Radiation Belts: From Discovery to the Van Allen Probes Era

Contact Info

Product

Resources

About