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Van Allen Probes Bibliography is from August 2012 through September 2021 Notice:
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Found 31 entries in the Bibliography.
Showing entries from 1 through 31
| 2021 |
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Abstract Radiation belt electrons undergo frequent acceleration, transport, and loss processes under various physical mechanisms. One of the most prevalent mechanisms is radial diffusion, caused by the resonant interactions between energetic electrons and ULF waves in the Pc4-5 band. An indication of this resonant interaction is believed to be the appearance of periodic flux oscillations. In this study, we report long-lasting, drift-periodic flux oscillations of relativistic and ultrarelativistic electrons with energies up t ... Zhao, Hong; Sarris, Theodore; Li, Xinlin; Weiner, Max; Huckabee, Isabela; Baker, Daniel; Jaynes, Allison; Kanekal, Shrikanth; Elkington, Scot; Barani, Mohammad; Tu, Weichao; Liu, Wenlong; Zhang, Dianjun; Hartinger, Michael; Published by: Journal of Geophysical Research: Space Physics Published on: 07/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2021JA029284 Radiation belt; multi-MeV electrons; radial diffusion; ULF waves; Wave-particle interaction; Phase space density radial gradient; Van Allen Probes |
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A Comparison of Radial Diffusion Coefficients in 1-D and 3-D Long-Term Radiation Belt Simulations AbstractRadial diffusion is one of the dominant physical mechanisms driving acceleration and loss of radiation belt electrons. A number of parameterizations for radial diffusion coefficients have been developed, each differing in the dataset used. Here, we investigate the performance of different parameterizations by Brautigam and Albert (2000), Brautigam et al. (2005), Ozeke et al. (2014), Ali et al. (2015); Ali et al. (2016); Ali (2016), and Liu et al. (2016) on long-term radiation belt modeling using the Versatile El ... Drozdov, A; Allison, H.; Shprits, Y; Elkington, S.R.; Aseev, N.A.; Published by: Journal of Geophysical Research: Space Physics Published on: 07/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028707 Radiation belts; radial diffusion; VERB code; Van Allen Probes |
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The Roles of the Magnetopause and Plasmapause in Storm-Time ULF Wave Power Enhancements Abstract Ultra Low Frequency (ULF) waves play a crucial role in transporting and coupling energy within the magnetosphere. During geomagnetic storms, dayside magnetospheric ULF wave power is highly variable with strong enhancements that are dominated by elevated solar wind driving. However, the radial distribution of ULF wave power is complex - controlled interdependently by external solar wind driving and the internal magnetospheric structuring. We conducted a statistical analysis of observed storm-time ULF wave power from ... Sandhu, J.; Rae, I.; Staples, F.; Hartley, D.; Walach, M.-T.; Elsden, T.; Murphy, K.; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2021JA029337 ULF waves; Geomagnetic storms; Van Allen Probes; radial diffusion; inner magnetosphere; plasmasphere |
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Modeling the Dynamics of Radiation Belt Electrons with Source and Loss Driven by the Solar Wind Abstract A radial diffusion model directly driven by the solar wind is developed to reproduce MeV electron variations between L=2-12 (L is L* in this study) from October 2012 to April 2015. The radial diffusion coefficient, internal source rate, quick loss due to EMIC waves, and slow loss due to hiss waves are all expressed in terms of the solar wind speed, dynamic pressure, and interplanetary magnetic field (IMF). The model achieves a prediction efficiency (PE) of 0.45 at L=5 and 0.51 at L=4 after converting the electron ph ... Xiang, Zheng; Li, Xinlin; Kapali, Sudha; Gannon, Jennifer; Ni, Binbin; Zhao, Hong; Zhang, Kun; Khoo, Leng; Published by: Journal of Geophysical Research: Space Physics Published on: 05/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028988 Radiation belt; Solar wind; flux prediction; radial diffusion; magnetopause shadowing; wave-particle interactions; Van Allen Probes |
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Abstract The impact of radial diffusion in storm time radiation belt dynamics is well-debated. In this study we quantify the changes and variability in radial diffusion coefficients during geomagnetic storms. A statistical analysis of Van Allen Probes data (2012 − 2019) is conducted to obtain measurements of the magnetic and electric power spectral densities for Ultra Low Frequency (ULF) waves, and corresponding radial diffusion coefficients. The results show global wave power enhancements occur during the storm main phase ... Sandhu, J.; Rae, I.; Wygant, J.; Breneman, A.; Tian, S.; Watt, C.; Horne, R.; Ozeke, L.; Georgiou, M.; Walach, M.-T.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA029024 ULF waves; radial diffusion; outer radiation belt; Van Allen Probes; Geomagnetic storms |
| 2020 |
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Simulations of Electron Flux Oscillations as Observed by MagEIS in Response to Broadband ULF Waves Coherent electron flux oscillations of hundreds of keV are often observed by the Van Allen Probes in the magnetosphere during quiet times in association with ultralow frequency (ULF) waves. They are observed in the form of periodic flux fluctuations, with a drift frequency that is energy dependent, but are not associated with drift echoes following storm- or substorm-related energetic particle injections. Instead, they are associated with the resonant interaction of electrons with ULF waves and are an indication of ongoing e ... Sarris, Theodore; Li, Xinlin; Temerin, Michael; Zhao, Hong; Khoo, Leng; Turner, Drew; Liu, Wenlong; Claudepierre, Seth; Published by: Journal of Geophysical Research: Space Physics Published on: 05/2020 YEAR: 2020 DOI: https://doi.org/10.1029/2020JA027798 electron flux oscillations; ULF waves; Magnetosphere; Radiation belts; radial diffusion; particle tracing simulations; Van Allen Probes |
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Bayesian Inference of Quasi-Linear Radial Diffusion Parameters using Van Allen Probes Abstract The Van Allen radiation belts in the magnetosphere have been extensively studied using models based on radial diffusion theory, which is derived from a quasi-linear approach with prescribed inner and outer boundary conditions. The 1D diffusion model requires the knowledge of a diffusion coefficient and an electron loss timescale, which is typically parameterized in terms of various quantities such as the spatial (L) coordinate or a geomagnetic index (e.g., Kp). These terms are typically empirically derived, not dire ... Sarma, Rakesh; Chandorkar, Mandar; Zhelavskaya, Irina; Shprits, Yuri; Drozdov, Alexander; Camporeale, Enrico; Published by: Journal of Geophysical Research: Space Physics Published on: 04/2020 YEAR: 2020 DOI: 10.1029/2019JA027618 radial diffusion; Magnetosphere; Bayesian inference; Van Allen radiation belt; Van Allen Probes |
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Bayesian Inference of Quasi-Linear Radial Diffusion Parameters using Van Allen Probes The Van Allen radiation belts in the magnetosphere have been extensively studied using models based on radial diffusion theory, which is derived from a quasi-linear approach with prescribed inner and outer boundary conditions. The 1D diffusion model requires the knowledge of a diffusion coefficient and an electron loss timescale, which is typically parameterized in terms of various quantities such as the spatial (L) coordinate or a geomagnetic index (e.g., Kp). These terms are typically empirically derived, not directly meas ... Sarma, Rakesh; Chandorkar, Mandar; Zhelavskaya, Irina; Shprits, Yuri; Drozdov, Alexander; Camporeale, Enrico; Published by: Journal of Geophysical Research: Space Physics Published on: 04/2020 YEAR: 2020 DOI: https://doi.org/10.1029/2019JA027618 radial diffusion; Magnetosphere; Bayesian inference; Van Allen radiation belt; Van Allen Probes |
| 2019 |
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Variability of the Proton Radiation Belt Significant steady but slow variability of radiation belt proton intensity, in the energy range \~19\textendash200 MeV and for L<2.4, has been observed in an empirical model derived from data taken by Van Allen Probes during 2013\textendash2019. It is compared to predictions of a theoretical model based on measured initial and boundary conditions. Two aspects of the variability are considered in detail and require adjustments to model parameters. Observed inward transport of proton intensity maxima near L=1.9 and associated ... Published by: Journal of Geophysical Research: Space Physics Published on: 07/2019 YEAR: 2019 DOI: 10.1029/2019JA026754 |
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We present the temporal evolution of electron Phase Space Density (PSD) in the outer radiation belt during the intense March 2015 geomagnetic storm. Comparing observed PSD profiles as a function of L* at fixed first, M, and second, K, adiabatic invariants with those produced by simulations is critical for determining the physical processes responsible for the outer radiation belt dynamics. Here we show that the bulk of the accelerated and enhanced outer radiation belt population consists of electrons with K < 0.17 G1/2Re. Fo ... Ozeke, L.; Mann, I.; Claudepierre, S.; Henderson, M.; Morley, S.; Murphy, K.; Olifer, L.; Spence, H.; Baker, D.; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2019 YEAR: 2019 DOI: 10.1029/2018JA026326 Local Acceleration; March 2015 storm; Phase space density; radial diffusion; Radiation belt; ULF waves; Van Allen Probes |
| 2018 |
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Inward radial diffusion driven by ULF waves has long been known to be capable of accelerating radiation belt electrons to very high energies within the heart of the belts, but more recent work has shown that radial diffusion values can be highly event-specific and mean values or empirical models may not capture the full significance of radial diffusion to acceleration events. Here we present an event of fast inward radial diffusion, occurring during a period following the geomagnetic storm of 17 March 2015. Ultra-relativisti ... Jaynes, A.; Ali, A.; Elkington, S.; Malaspina, D.; Baker, D.; Li, X.; Kanekal, S.; Henderson, M.; Kletzing, C.; Wygant, J.; Published by: Geophysical Research Letters Published on: 09/2018 YEAR: 2018 DOI: 10.1029/2018GL079786 Magnetosphere; radial diffusion; Radiation belts; ULF waves; Van Allen Probes |
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A Statistical Survey of Radiation Belt Dropouts Observed by Van Allen Probes A statistical analysis on the radiation belt dropouts is performed based on 4 years of electron phase space density data from the Van Allen Probes. The μ, K, and L* dependence of dropouts and their driving mechanisms and geomagnetic and solar wind conditions are investigated using electron phase space density data sets for the first time. Our results suggest that electronmagnetic ion cyclotron (EMIC) wave scattering is the dominant dropout mechanism at low L* region, which requires the most active geomagnetic and solar wind ... Xiang, Zheng; Tu, Weichao; Ni, Binbin; Henderson, M.; Cao, Xing; Published by: Geophysical Research Letters Published on: 08/2018 YEAR: 2018 DOI: 10.1029/2018GL078907 EMIC wave; magnetopause shadowing; Phase space density; radial diffusion; radiation belt dropout; Van Allen Probes; wave particle interaction |
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We simulate the radiation belt electron flux enhancements during selected Geospace Environment Modeling (GEM) challenge events to quantitatively compare the major processes involved in relativistic electron acceleration under different conditions. Van Allen Probes observed significant electron flux enhancement during both the storm time of 17\textendash18 March 2013 and non\textendashstorm time of 19\textendash20 September 2013, but the distributions of plasma waves and energetic electrons for the two events were dramaticall ... Ma, Q.; Li, W.; Bortnik, J.; Thorne, R.; Chu, X.; Ozeke, L.; Reeves, G.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Engebretson, M.; Spence, H.; Baker, D.; Blake, J.; Fennell, J.; Claudepierre, S.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2018 YEAR: 2018 DOI: 10.1002/2017JA025114 electron accelerationl whistler mode waves; radial diffusion; radiation belt simulation; Van Allen Probes; Van Allen Probes observation |
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Previous studies have revealed a typical picture that seed electrons are transported inward under the drive of radial diffusion and then accelerated via chorus to relativistic energies. Here we show a potentially different process during the 2\textendash3 October 2013 storm when Van Allen Probes observed extremely rapid (by about 50 times in 2 h) flux enhancements of relativistic (1.8\textendash3.4 MeV) electrons but without distinct chorus at lower L-shells. Meanwhile, Time History of Events and Macroscale Interactions duri ... Liu, Si; Yan, Qi; Yang, Chang; Zhou, Qinghua; He, Zhaoguo; He, Yihua; Gao, Zhonglei; Xiao, Fuliang; Published by: Geophysical Research Letters Published on: 02/2018 YEAR: 2018 DOI: 10.1002/grl.v45.310.1002/2017GL076513 chorus-driven acceleration; radial diffusion; Radiation belt; THEMIS; Van Allen Probes |
| 2017 |
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Rapid loss of radiation belt relativistic electrons by EMIC waves How relativistic electrons are lost is an important question surrounding the complex dynamics of the Earth\textquoterights outer radiation belt. Radial loss to the magnetopause and local loss to the atmosphere are two main competing paradigms. Here, on the basis of the analysis of a radiation belt storm event on 27 February 2014, we present new evidence for the EMIC wave-driven local precipitation loss of relativistic electrons in the heart of the outer radiation belt. During the main phase of this storm, the radial profile ... Su, Zhenpeng; Gao, Zhonglei; Zheng, Huinan; Wang, Yuming; Wang, Shui; Spence, H.; Reeves, G.; Baker, D.; Wygant, J.; Published by: Journal of Geophysical Research: Space Physics Published on: 08/2017 YEAR: 2017 DOI: 10.1002/2017JA024169 electron loss; EMIC waves; pitch angle scattering; radial diffusion; Radiation belts; Van Allen Probes; Wave-particle interaction |
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On the Relationship Between Electron Flux Oscillations and ULF Wave-Driven Radial Transport The objective of this study is to investigate the relationship between the levels of electron flux oscillations and radial diffusion for different Phase Space Density (PSD) gradients, through observation and particle tracing simulations under the effect of model Ultra Low Frequency (ULF) fluctuations. This investigation aims to demonstrate that electron flux oscillation is associated with and could be used as an indicator of ongoing radial diffusion. To this direction, flux oscillations are observed through the Van Allen Pro ... Sarris, Theodore; Li, Xinlin; Temerin, Michael; Zhao, Hong; Califf, Sam; Liu, Wenlong; Ergun, Robert; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2017 YEAR: 2017 DOI: 10.1002/2016JA023741 Flux Oscillations; MAGEis; EMFISIS; EFW; Phase space density; radial diffusion; Radiation belts; Van Allen Probes |
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The 17 March 2015 St. Patrick\textquoterights Day Storm is the largest geomagnetic storm to date of Solar Cycle 24, with a Dst of -223 nT. The magnetopause moved inside geosynchronous orbit under high solar wind dynamic pressure and strong southward IMF Bz causing loss, however a subsequent drop in pressure allowed for rapid rebuilding of the radiation belts. The 17 March 2013 storm also shows similar effects on outer zone electrons: first a rapid dropout due to inward motion of the magnetopause followed by rapid increase in ... Li, Zhao; Hudson, Mary; Patel, Maulik; Wiltberger, Michael; Boyd, Alex; Turner, Drew; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2017 YEAR: 2017 DOI: 10.1002/2016JA023846 March 2013; March 2015; radial diffusion; Radiation belt; Van Allen Probes |
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In September 2014 an unusually long-lasting (≳10 days) ultra-relativistic electron flux depletion occurred in the outer radiation belt despite ongoing solar wind forcing. We simulate this period using a ULF wave radial diffusion model, driven by observed ULF wave power coupled to flux variations at the outer boundary at L* = 5, including empirical electron loss models due to chorus and hiss wave scattering. Our results show that unexplained rapid main phase loss, that depletes the belt within hours, is essential to explain ... Ozeke, Louis; Mann, Ian; Murphy, Kyle; Sibeck, David; Baker, Daniel; Published by: Geophysical Research Letters Published on: 03/2017 YEAR: 2017 DOI: 10.1002/2017GL072811 radial diffusion; Radiation belt; ULF waves; ultrarelativistic; Van Allen Probes; wave-particle interactions |
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Radial diffusion is one of the dominant physical mechanisms that drives acceleration and loss of the radiation belt electrons, which makes it very important for nowcasting and forecasting space weather models. We investigate the sensitivity of the two parameterizations of the radial diffusion of Brautigam and Albert (2000) and Ozeke et al. (2014) on long-term radiation belt modeling using the Versatile Electron Radiation Belt (VERB). Following Brautigam and Albert (2000) and Ozeke et al. (2014), we first perform 1-D radial d ... Drozdov, A; Shprits, Y; Aseev, N.; Kellerman, A.; Reeves, G.; Published by: Space Weather Published on: 01/2017 YEAR: 2017 DOI: 10.1002/swe.v15.110.1002/2016SW001426 radial diffusion; Radiation belts; Van Allen Probes; VERB code |
| 2016 |
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Electric and Magnetic Radial Diffusion Coefficients Using the Van Allen Probes Data ULF waves are a common occurrence in the inner magnetosphere and they contribute to particle motion, significantly, at times. We used the magnetic and the electric field data from the EMFISIS and the EFW instruments on board the Van Allen Probes to estimate the ULF wave power in the compressional component of the magnetic field and the azimuthal component of the electric field, respectively. Using L*, Kp, and MLT as parameters, we conclude that the noon sector contains higher ULF Pc-5 wave power compared with the other MLT s ... Ali, Ashar; Malaspina, David; Elkington, Scot; Jaynes, Allison; Chan, Anthony; Wygant, John; Kletzing, Craig; Published by: Journal of Geophysical Research: Space Physics Published on: 08/2016 YEAR: 2016 DOI: 10.1002/2016JA023002 Electric and Magnetic Components; radial diffusion; RBSP; Van Allen Probes |
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The 17\textendash18 March 2015 storm is the largest geomagnetic storm in the Van Allen Probes era to date. The Lyon-Fedder-Mobarry global MHD model has been run for this event using ARTEMIS data as solar wind input. The ULF wave power spectral density of the azimuthal electric field and compressional magnetic field is analyzed in the 0.5\textendash8.3 mHz range. The lowest three azimuthal modes account for 70\% of the total power during quiet times. However, during high activity, they are not exclusively dominant. The calcul ... Li, Zhao; Hudson, Mary; Paral, Jan; Wiltberger, Michael; Turner, Drew; Published by: Journal of Geophysical Research: Space Physics Published on: 07/2016 YEAR: 2016 DOI: 10.1002/2016JA022508 March 2015; radial diffusion; radial diffusion coefficient; Radiation belt; ULF waves; Van Allen Probes |
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Inner zone and slot electron radial diffusion revisited Using recent data from NASA\textquoterights Van Allen Probes, we estimate the quiet time radial diffusion coefficients for electrons in the inner radiation belt (L < 3) with energies from ~50 to 750 keV. The observations are consistent with dynamics dominated by pitch angle scattering and radial diffusion. We use a coordinate system in which these two modes of diffusion are separable. Then we integrate phase space density over pitch angle to obtain a \textquotedblleftbundle content\textquotedblright that is invariant to pitc ... O\textquoterightBrien, T.; Claudepierre, S.; Guild, T.; Fennell, J.; Turner, D.; Blake, J.; Clemmons, J.; Roeder, J.; Published by: Geophysical Research Letters Published on: 07/2016 YEAR: 2016 DOI: 10.1002/2016GL069749 Inner zone; radial diffusion; Radiation belt; Van Allen Probes |
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Various physical processes are known to cause acceleration, loss, and transport of energetic electrons in the Earth\textquoterights radiation belts, but their quantitative roles in different time and space need further investigation. During the largest storm over the past decade (17 March 2015), relativistic electrons experienced fairly rapid acceleration up to ~7 MeV within 2 days after an initial substantial dropout, as observed by Van Allen Probes. In the present paper, we evaluate the relative roles of various physical p ... Li, W.; Ma, Q.; Thorne, R.; Bortnik, J.; Zhang, X.-J.; Li, J.; Baker, D.; Reeves, G.; Spence, H.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Blake, J.; Fennell, J.; Kanekal, S.; Angelopoulos, V.; Green, J.; Goldstein, J.; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2016 YEAR: 2016 DOI: 10.1002/jgra.v121.610.1002/2016JA022400 chorus-driven local acceleration; Electron acceleration; radial diffusion; Van Allen Probes |
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The radial and local diffusion processes induced by various plasma waves govern the highly energetic electron dynamics in the Earth\textquoterights radiation belts, causing distinct characteristics in electron distributions at various energies. In this study, we present our simulation results of the energetic electron evolution during a geomagnetic storm using the University of California, Los Angeles 3-D diffusion code. Following the plasma sheet electron injections, the electrons at different energy bands detected by the M ... Ma, Q.; Li, W.; Thorne, R.; Nishimura, Y.; Zhang, X.-J.; Reeves, G.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Henderson, M.; Spence, H.; Baker, D.; Blake, J.; Fennell, J.; Angelopoulos, V.; Published by: Journal of Geophysical Research: Space Physics Published on: 05/2016 YEAR: 2016 DOI: 10.1002/2016JA022507 electron acceleration and loss; energy-dependent diffusion; radial diffusion; radiation belt simulation; Van Allen Probes |
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Inward diffusion and loss of radiation belt protons Radiation belt protons in the kinetic energy range 24 to 76 MeV are being measured by the Relativistic Electron Proton Telescope on each of the two Van Allen Probes. Data have been processed for the purpose of studying variability in the trapped proton intensity during October 2013 to August 2015. For the lower energies (≲32 MeV), equatorial proton intensity near L = 2 showed a steady increase that is consistent with inward diffusion of trapped solar protons, as shown by positive radial gradients in phase space density at ... Selesnick, R.; Baker, D.; Jaynes, A.; Li, X.; Kanekal, S.; Hudson, M.; Kress, B.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2016 YEAR: 2016 DOI: 10.1002/2015JA022154 |
| 2015 |
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We used the fluxgate magnetometer data from Combined Release and Radiation Effects Satellite (CRRES) to estimate the power spectral density (PSD) of the compressional component of the geomagnetic field in the \~1 mHz to \~8 mHz range. We conclude that magnetic wave power is generally higher in the noon sector for quiet times with no significant difference between the dawn, dusk, and the midnight sectors. However, during high Kp activity, the noon sector is not necessarily dominant anymore. The magnetic PSDs have a very disti ... Ali, Ashar; Elkington, Scot; Tu, Weichao; Ozeke, Louis; Chan, Anthony; Friedel, Reiner; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2015 YEAR: 2015 DOI: 10.1002/2014JA020419 |
| 2014 |
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Radial diffusion simulations of the 20 September 2007 radiation belt dropout This is a study of a dropout of radiation belt electrons, associated with an isolated solar wind density pulse on 20 September 2007, as seen by the solid-state telescopes (SST) detectors on THEMIS (Time History of Events and Macroscale Interactions during Substorms). Omnidirectional fluxes were converted to phase space density at constant invariants M = 700 MeV G-1 and K = 0.014 RE G1/2, with the assumption of local pitch angle α ≈ 80\textdegree and using the T04 magnetic field model. The last closed drift shell, which wa ... Published by: Annales Geophysicae Published on: 11/2014 YEAR: 2014 DOI: 10.5194/angeo-32-925-2014 |
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A ULF wave driver of ring current energization ULF wave radial diffusion plays an important role in the transport of energetic electrons in the outer radiation belt, yet similar ring current transport is seldom considered even though ions satisfy a nearly identical drift resonance condition albeit without the relativistic correction. By examining the correlation between ULF wave power and the response of the ring current, characterized by Dst, we demonstrate a definite correlation between ULF wave power and Dst. Significantly, the lagged correlation peaks such that ULF w ... Murphy, Kyle; Mann, Ian; Ozeke, Louis; Published by: Geophysical Research Letters Published on: 10/2014 YEAR: 2014 DOI: 10.1002/grl.v41.1910.1002/2014GL061253 Dst; radial diffusion; ring current dynamics; ULF waves; wave particle interactions |
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March 2013 provided the first equinoctial period when all of the instruments on the Van Allen Probes spacecraft were fully operational. This interval was characterized by disturbances of outer zone electrons with two timescales of variation, diffusive and rapid dropout and restoration [Baker et al., 2014]. A radial diffusion model was applied to the month-long interval to confirm that electron phase space density is well described by radial diffusion for the whole month at low first invariant <=400 MeV/G, but peaks in phase ... Li, Zhao; Hudson, Mary; Jaynes, Allison; Boyd, Alexander; Malaspina, David; Thaller, Scott; Wygant, John; Henderson, Michael; Published by: Journal of Geophysical Research: Space Physics Published on: 10/2014 YEAR: 2014 DOI: 10.1002/2014JA020359 |
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Estimates of the power per mode number of broadband ULF waves at geosynchronous orbit In studies of radial diffusion processes in the magnetosphere it is well known that ultralow frequency (ULF) waves of frequency mωd can resonantly interact with particles of drift frequency ωd, where m is the waves\textquoteright azimuthal mode number. Due to difficulties in estimating m, an oversimplifying assumption is often made in simulations, namely that all ULF wave power is located at a single mode number. In this paper a technique is presented for extracting information on the distribution of ULF power in a range o ... Published by: Journal of Geophysical Research: Space Physics Published on: 07/2014 YEAR: 2014 DOI: 10.1002/2013JA019238 Magnetosphere; mode number; radial diffusion; Radiation belts; ULF waves; ultralow frequency |
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Radial diffusion comparing a THEMIS statistical model with geosynchronous measurements as input The outer boundary energetic electron flux is used as a driver in radial diffusion calculations, and its precise determination is critical to the solution. A new model was proposed recently based on Time History of Events and Macroscale Interactions during Substorms (THEMIS) measurements to express the boundary flux as three fit functions of solar wind parameters in a response window that depend on energy and which solar wind parameter is used: speed, density, or both. The Dartmouth radial diffusion model has been run using ... Li, Zhao; Hudson, Mary; Chen, Yue; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2014 YEAR: 2014 DOI: 10.1002/jgra.v119.310.1002/2013JA019320 outer boundary; radial diffusion; Radiation belt; Van Allen Probes |
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