Energy-dependent Boundaries of Earth's Radiation Belt Electron Slot Region

2021 ◽  
Vol 922 (2) ◽  
pp. 246
Author(s):  
Yang Mei ◽  
Yasong Ge ◽  
Aimin Du ◽  
Xudong Gu ◽  
Danny Summers ◽  
...  
Keyword(s):  
Empirical Model ◽  
Radiation Belt ◽  
Lower Boundary ◽  
Recovery Process ◽  
Compression Process ◽  
Inner Magnetosphere ◽  
P Index ◽  
Energy Dependent ◽  
Geomagnetic Activities ◽  
Dependent Processes

Abstract The variations in radiation belt boundaries reflect competition between acceleration and loss physical processes of energetic electrons, which is an important issue for radiation belts of planets with an internal magnetic field (e.g., Earth, Jupiter, and Saturn). Based on high-quality measurements from Van Allen Probes spanning the years 2014–2018, we develop an empirical model of the energy-dependent boundaries of Earth's electron radiation belt slot region, showing that the lower boundary follows a logarithmic function of the electron energy while the upper boundary is controlled by two competing energy-dependent processes, namely compression and recovery. The compression process relates linearly to a 15 hr averaged Kp index, while the recovery process is found to be approximately proportional to time. Detailed data-model comparisons demonstrate that our model, using only the Kp index and time epoch as inputs, reconstructs the slot region boundaries in real time for 200 keV to 2 MeV electrons under varying geomagnetic conditions. Such a data-driven empirical model is prerequisite to understanding the dynamic changes of the slot region in response to both solar and geomagnetic activities. The model can be readily incorporated into future global simulations of radiation belt electron dynamics in Earth's inner magnetosphere and provide new insights into the study of Saturn's and Jupiter's radiation belt variability.

scholarly journals Empirical model of proton fluxes in the equatorial inner magnetosphere: Development

2001 ◽  
Vol 106 (A11) ◽  
pp. 25713-25729 ◽  
Author(s):  
A. Milillo ◽  
S. Orsini ◽  
I. A. Daglis
Keyword(s):  
Empirical Model ◽  
Inner Magnetosphere ◽  
Proton Fluxes

scholarly journals Simulation of energy-dependent electron diffusion processes in the Earth's outer radiation belt

2016 ◽  
Vol 121 (5) ◽  
pp. 4217-4231 ◽  
Author(s):  
Q. Ma ◽  
W. Li ◽  
R. M. Thorne ◽  
Y. Nishimura ◽  
X.-J. Zhang ◽  
...  
Keyword(s):  
Radiation Belt ◽  
Diffusion Processes ◽  
Outer Radiation Belt ◽  
Electron Diffusion ◽  
Energy Dependent

scholarly journals Empirical model of lower band chorus wave distribution in the outer radiation belt

2015 ◽  
Vol 120 (12) ◽  
pp. 10,425-10,442 ◽  
Author(s):  
O. V. Agapitov ◽  
A. V. Artemyev ◽  
D. Mourenas ◽  
F. S. Mozer ◽  
V. Krasnoselskikh
Keyword(s):  
Empirical Model ◽  
Radiation Belt ◽  
Outer Radiation Belt ◽  
Lower Band ◽  
Wave Distribution ◽  
Chorus Wave

The dynamics of the inner boundary of the outer radiation belt during geomagnetic storms

2020 ◽  
Author(s):  
Xiaofei Shi ◽  
Jie Ren ◽  
Qiugang Zong
Keyword(s):  
Radiation Belt ◽  
Electron Flux ◽  
Geomagnetic Storms ◽  
Minimum Energy ◽  
Onset Time ◽  
Recovery Phase ◽  
Outer Radiation Belt ◽  
H Index ◽  
Late Recovery ◽  
Energy Dependent

<p>We present a statistical study of energy-dependent and L shell-dependent inner boundary of the outer radiation belt during 37 isolated geomagnetic storms using observations from Van Allen Probes from 2013 to 2017. There are mutual transformations between "V-shaped" and "S-shaped" inner boundaries during different storm phases, resulting from the competition among electron loss, radial transport and local acceleration. The radial position, onset time, E<sub>st</sub> (the minimum energy at L<sub>st</sub> where the inner boundary starts to exhibit an S-shaped form), and the radial width of S-shaped boundary (ΔL) are quantitatively defined according to the formation of a reversed energy spectrum (electron flux going up with increasing energies from hundreds of keV to ~1 MeV) from a kappa-like spectrum (electron flux steeply falling with increasing energies). The case and statistical results present that (1) The inner boundary has repeatable features associated with storms: the inner boundary is transformed from S-shaped to V-shaped form in several hours during the storm commencement and main phase, and retains in the V-shaped form for several days until it evolves into S-shaped during late recovery phase; (2) ΔL shows positive correlation with SYM-H index; (3) The duration of the V-shaped form is positively correlated with the storm intensity and the duration of the recovery phase; (4) The minimum energy E<sub>st</sub> are mainly distributed in the range of 100-550 keV. All these findings have important implications for understanding the dynamics of energetic electrons in the slot region and the outer radiation belt during geomagnetic storms.</p>

Empirical model of proton fluxes in the equatorial inner magnetosphere: 2. Properties and applications

2003 ◽  
Vol 108 (A5) ◽  
Author(s):  
A. Milillo ◽  
S. Orsini ◽  
D. C. Delcourt ◽  
A. Mura ◽  
S. Massetti ◽  
...  
Keyword(s):  
Empirical Model ◽  
Inner Magnetosphere ◽  
Proton Fluxes

scholarly journals On the relative roles of dynamics and chemistry governing the abundance and diurnal variation of low latitude thermospheric nitric oxide

2018 ◽  
Author(s):  
David E. Siskind ◽  
McArthur Jones Jr. ◽  
Douglas P. Drob ◽  
John P. McCormack ◽  
Mark E. Hervig ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Diurnal Variation ◽  
Empirical Model ◽  
General Circulation ◽  
Lower Boundary ◽  
Circulation Model ◽  
Potential Conflict ◽  
Solar Occultation ◽  
Free Running ◽  
Data Discrepancy

Abstract. We use data from two NASA satellites, the Thermosphere Ionosphere Energetics and Dynamics (TIMED) and the Aeronomy of Ice in the Mesosphere (AIM) satellites in conjunction with model simulations from the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM) to elucidate the key dynamical and chemical factors governing the abundance and diurnal variation of nitric oxide (NO) at near solar minimum conditions and low latitudes. This analysis was enabled by the recent orbital precession of the AIM satellite which caused the solar occultation pattern measured by the Solar Occultation for Ice Experiment (SOFIE) to migrate down to low and mid latitudes for specific periods of time. We use a month of NO data collected in January 2017 to compare with two versions of the TIME-GCM, one driven solely by climatological tides and analysis-derived planetary waves at the lower boundary and free running at all other altitudes, while the other is constrained by a high-altitude analysis from the Navy Global Environmental Model (NAVGEM) up to the mesopause. We also compare SOFIE data with a NO climatology from the Nitric Oxide Empirical Model (NOEM). Both SOFIE and NOEM yield peak NO abundances of around 4 × 107 cm−3; however, the SOFIE profile peaks about 6–8 km lower than NOEM. We show that this difference is likely a local time effect; SOFIE being a dawn measurement and NOEM representing late morning/near noon. The constrained version of TIME-GCM exhibits a low altitude dawn peak while the model that is forced solely at the lower boundary and free running above does not. We attribute this difference due to a phase change in the semi-diurnal tide in the NAVGEM-constrained model causing descent of high NO mixing ratio air near dawn. This phase difference between the two models arises due to differences in the mesospheric zonal mean zonal winds. Regarding the absolute NO abundance, all versions of the TIME-GCM overestimate this. Tuning the model to yield calculated atomic oxygen in agreement with TIMED data helps, but is insufficient. Further, the TIME-GCM underestimates the electron density [e-] as compared with the International Reference Ionosphere empirical model. This suggests a potential conflict with the requirements of NO modeling and [e-] modeling since one solution typically used to increase model [e-] is to increase the solar soft X ray flux which would, in this case, worsen the NO model/data discrepancy.

scholarly journals Plasma Waves in the Inner Magnetosphere

2021 ◽  
pp. 85-119
Author(s):  
Hannu E. J. Koskinen ◽  
Emilia K. J. Kilpua
Keyword(s):  
Radiation Belt ◽  
Low Frequency ◽  
Plasma Waves ◽  
Mhd Waves ◽  
Particle Interactions ◽  
Inner Magnetosphere ◽  
Very Low Frequency ◽  
Link Type ◽  
Wave Modes

AbstractUnderstanding the role of plasma waves, extending from magnetohydrodynamic (MHD) waves at ultra-low-frequency (ULF) oscillations in the millihertz range to very-low-frequency (VLF) whistler-mode emissions at frequencies of a few kHz, is necessary in studies of sources and losses of radiation belt particles. In order to make this theoretically heavy part of the book accessible to a reader, who is not familiar with wave–particle interactions, we have divided the treatise into three chapters. In the present chapter we introduce the most important wave modes that are critical to the dynamics of radiation belts. The drivers of these waves are discussed in Chap. 10.1007/978-3-030-82167-8_5 and the roles of the wave modes as sources and losses of radiation belt particles are dealt with in Chap. 10.1007/978-3-030-82167-8_6.

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