Bibliography



Found 259 entries in the Bibliography.


Showing entries from 151 through 200


2016

Electron butterfly distribution modulation by magnetosonic waves

The butterfly pitch angle distribution is observed as a dip in an otherwise normal distribution of electrons centered about αeq=90\textdegree. During storm times, the formation of the butterfly distribution on the nightside magnetosphere has been attributed to L shell splitting combined with magnetopause shadowing and strong positive radial flux gradients. It has been shown that this distribution can be caused by combined chorus and magnetosonic wave scattering where the two waves work together but at different local times. ...

Maldonado, Armando; Chen, Lunjin; Claudepierre, Seth; Bortnik, Jacob; Thorne, Richard; Spence, Harlan;

YEAR: 2016     DOI: 10.1002/2016GL068161

butterfly; electron; magnetosonic; Magnetosphere; Van Allen Probes; wave particle interaction

Formation of Energetic Electron Butterfly Distributions by Magnetosonic Waves via Landau Resonance

Radiation belt electrons can exhibit different types of pitch angle distributions in response to various magnetospheric processes. Butterfly distributions, characterized by flux minima at pitch angles around 90\textdegree, are broadly observed in both the outer and inner belts and the slot region. Butterfly distributions close to the outer magnetospheric boundary have been attributed to drift shell splitting and losses to the magnetopause. However, their occurrence in the inner belt and the slot region has hitherto not been ...

Li, Jinxing; Ni, Binbin; Ma, Qianli; Xie, Lun; Pu, Zuyin; Fu, Suiyan; Thorne, R.; Bortnik, J.; Chen, Lunjin; Li, Wen; Baker, Daniel; Kletzing, Craig; Kurth, William; Hospodarsky, George; Fennell, Joseph; Reeves, Geoffrey; Spence, Harlan; Funsten, Herbert; Summers, Danny;

YEAR: 2016     DOI: 10.1002/2016GL067853

butterfly distributions; energetic electrons; Landau resonance; magnetosonic waves; Radiation belt; Van Allen Probes

Formation of Energetic Electron Butterfly Distributions by Magnetosonic Waves via Landau Resonance

Radiation belt electrons can exhibit different types of pitch angle distributions in response to various magnetospheric processes. Butterfly distributions, characterized by flux minima at pitch angles around 90\textdegree, are broadly observed in both the outer and inner belts and the slot region. Butterfly distributions close to the outer magnetospheric boundary have been attributed to drift shell splitting and losses to the magnetopause. However, their occurrence in the inner belt and the slot region has hitherto not been ...

Li, Jinxing; Ni, Binbin; Ma, Qianli; Xie, Lun; Pu, Zuyin; Fu, Suiyan; Thorne, R.; Bortnik, J.; Chen, Lunjin; Li, Wen; Baker, Daniel; Kletzing, Craig; Kurth, William; Hospodarsky, George; Fennell, Joseph; Reeves, Geoffrey; Spence, Harlan; Funsten, Herbert; Summers, Danny;

YEAR: 2016     DOI: 10.1002/2016GL067853

butterfly distributions; energetic electrons; Landau resonance; magnetosonic waves; Radiation belt; Van Allen Probes

Ultrarelativistic electron butterfly distributions created by parallel acceleration due to magnetosonic waves

The Van Allen Probe observations during the recovery phase of a large storm that occurred on 17 March 2015 showed that the ultrarelativistic electrons at the inner boundary of the outer radiation belt (L* = 2.6\textendash3.7) exhibited butterfly pitch angle distributions, while the inner belt and the slot region also showed evidence of sub-MeV electron butterfly distributions. Strong magnetosonic waves were observed in the same regions and at the same time periods as these butterfly distributions. Moreover, when these magnet ...

Li, Jinxing; Bortnik, Jacob; Thorne, Richard; Li, Wen; Ma, Qianli; Baker, Daniel; Reeves, Geoffrey; Fennell, Joseph; Spence, Harlan; Kletzing, Craig; Kurth, William; Hospodarsky, George; Angelopoulos, Vassilis; Blake, Bernard.;

YEAR: 2016     DOI: 10.1002/2016JA022370

butterfly distributions; Landau resonance; magnetosonic waves; Radiation belt; Van Allen Probes

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.;

YEAR: 2016     DOI: 10.1002/2015JA022154

protons; radial diffusion; Radiation belt; Van Allen Probes

Forecasting and remote sensing outer belt relativistic electrons from low Earth orbit

This study demonstrates the feasibility and reliability of using observations from low Earth orbit (LEO) to forecast and nowcast relativistic electrons in the outer radiation belt. We first report a high cross-energy, cross-pitch-angle coherence discovered between the trapped MeV electrons and precipitating approximately hundreds (~100s) of keV electrons\textemdashobserved by satellites with very different altitudes\textemdashwith correlation coefficients as high as ≳ 0.85. Based upon the coherence, we then tested the feas ...

Chen, Yue; Reeves, Geoffrey; Cunningham, Gregory; Redmon, Robert; Henderson, Michael;

YEAR: 2016     DOI: 10.1002/2015GL067481

forecast and nowcast; hundreds of keV precipitating electrons; LEO observations; Radiation belts; relativistic electrons; wave particle interactions

2015

Survey of radiation belt energetic electron pitch angle distributions based on the Van Allen Probes MagEIS measurements

A statistical survey of electron pitch angle distributions (PADs) is performed based on the pitch angle resolved flux observations from the Magnetic Electron Ion Spectrometer (MagEIS) instrument on board the Van Allen Probes during the period from 1 October 2012 to 1 May 2015. By fitting the measured PADs to a sinnα form, where α is the local pitch angle and n is the power law index, we investigate the dependence of PADs on electron kinetic energy, magnetic local time (MLT), the geomagnetic Kp index and L-shell. The differ ...

Shi, Run; Summers, Danny; Ni, Binbin; Fennell, Joseph; Blake, Bernard; Spence, Harlan; Reeves, Geoffrey;

YEAR: 2015     DOI: 10.1002/2015JA021724

pitch angle distributions; Van Allen Probes

Electron scattering by magnetosonic waves in the inner magnetosphere

We investigate the importance of electron scattering by magnetosonic waves in the Earth\textquoterights inner magnetosphere. A statistical survey of the magnetosonic wave amplitude and wave frequency spectrum, as a function of geomagnetic activity, is performed using the Van Allen Probes wave measurements, and is found to be generally consistent with the wave distribution obtained from previous spacecraft missions. Outside the plasmapause the statistical frequency distribution of magnetosonic waves follows the variation of t ...

Ma, Qianli; Li, Wen; Thorne, Richard; Bortnik, Jacob; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

YEAR: 2015     DOI: 10.1002/2015JA021992

Electron scattering; magnetosonic waves; Van Allen Probes; Van Allen Probes statistics

In-flight performance of the Van Allen Probes RF telecommunications system

The NASA Van Allen Probes mission (previously called the Radiation Belt Storm Probes) successfully launched on 30 August 2012. The twin spacecraft, designed, built, and operated by The Johns Hopkins University Applied Physics Laboratory (JHU/APL), has been successfully operating within Earth׳s radiation belts since then, returning critical science data revealing new insights into the physics of the radiation belts. Because of the extreme radiation environment, all spacecraft subsystems including the communications system ha ...

Srinivasan, Dipak; Adams, Norm; Wallis, Robert;

YEAR: 2015     DOI: 10.1016/j.actaastro.2015.05.001

Van Allen Probes

Responses of relativistic electron fluxes in the outer radiation belt to geomagnetic storms

Geomagnetic storms can either increase or decrease relativistic electron fluxes in the outer radiation belt. A statistical survey of 84 isolated storms demonstrates that geomagnetic storms preferentially decrease relativistic electron fluxes at higher energies, while flux enhancements are more common at lower energies. In about 87\% of the storms, 0.3\textendash2.5 MeV electron fluxes show an increase, whereas 2.5\textendash14 MeV electron fluxes increase in only 35\% of the storms. Superposed epoch analyses suggest that suc ...

Xiong, Ying; Xie, Lun; Pu, Zuyin; Fu, Suiyan; Chen, Lunjin; Ni, Binbin; Li, Wen; Li, Jinxing; Guo, Ruilong; Parks, G.;

YEAR: 2015     DOI: 10.1002/2015JA021440

energy dependence; Geomagnetic storm; Radiation belts; relativistic electrons; Solar wind

On the formation and origin of substorm growth phase/onset auroral arcs inferred from conjugate space-ground observations

Magnetotail processes and structures related to substorm growth phase/onset auroral arcs remain poorly understood mostly due to the lack of adequate observations. In this study we make a comparison between ground-based optical measurements of the premidnight growth phase/onset arcs at subauroral latitudes and magnetically conjugate measurements made by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) at ~780 km in altitude and by the Van Allen Probe B (RBSP-B) spacecraft crossing L values o ...

Motoba, T.; Ohtani, S.; Anderson, B.; Korth, H.; Mitchell, D.; Lanzerotti, L.; Shiokawa, K.; Connors, M.; Kletzing, C.; Reeves, G.;

YEAR: 2015     DOI: 10.1002/jgra.v120.1010.1002/2015JA021676

FACs; growth phase/onset arc; M-I coupling; Van Allen Probes

Local time distributions of repetition periods for rising tone lower band chorus waves in the magnetosphere

Whistler mode chorus waves generally occur outside the plasmapause in the magnetosphere. The most striking feature of the waves is their occurrence in discrete elements. One of the parameters that describe the discrete elements is the repetition period (Trp), the time between consecutive elements. The Trp has not been studied statistically before. We use high-resolution waveform data to derive distributions of Trp for different local times. We find that the average Trp for the nightside (0.56 s) and dawnside (0.53 s) are sma ...

Shue, Jih-Hong; Hsieh, Yi-Kai; W. Y. Tam, Sunny; Wang, Kaiti; Fu, Hui; Bortnik, Jacob; Tao, Xin; Hsieh, Wen-Chieh; Pi, Gilbert;

YEAR: 2015     DOI: 10.1002/2015GL066107

Chorus; local time distribution; repetition period

Measurement of inner radiation belt electrons with kinetic energy above 1~MeV

Data from the Proton-Electron Telescope on the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) satellite, taken during 1992\textendash2009, are analyzed for evidence of inner radiation belt electrons with kinetic energy E > 1 MeV. It is found that most of the data from a detector combination with a nominal energy threshold of 1 MeV were, in fact, caused by a chance coincidence response to lower energy electrons or high-energy protons. In particular, there was no detection of inner belt or slot region electron ...

Selesnick, R.;

YEAR: 2015     DOI: 10.1002/2015JA021387

electrons; Inner zone; Radiation belt

\textquotedblleftTrunk-like\textquotedblright heavy ion structures observed by the Van Allen Probes

Dynamic ion spectral features in the inner magnetosphere are the observational signatures of ion acceleration, transport, and loss in the global magnetosphere. We report \textquotedbllefttrunk-like\textquotedblright ion structures observed by the Van Allen Probes on 2 November 2012. This new type of ion structure looks like an elephant\textquoterights trunk on an energy-time spectrogram, with the energy of the peak flux decreasing Earthward. The trunks are present in He+ and O+ ions but not in H+. During the event, ion energ ...

Zhang, J.-C.; Kistler, L.; Spence, H.; Wolf, R.; Reeves, G.; Skoug, R.; Funsten, H.; Larsen, B.; Niehof, J.; MacDonald, E.; Friedel, R.; Ferradas, C.; Luo, H.;

YEAR: 2015     DOI: 10.1002/2015JA021822

inner magnetosphere; ion injection; Ion structure; magnetic cloud; magnetic storm; Van Allen Probes

Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Validation with conjunctive Van Allen Probes observations

Plasmaspheric hiss plays an important role in controlling the overall structure and dynamics of the Earth\textquoterights radiation belts. The interaction of plasmaspheric hiss with radiation belt electrons is commonly evaluated using diffusion codes, which rely on statistical models of wave observations that may not accurately reproduce the instantaneous global wave distribution, or the limited in-situ satellite wave measurements from satellites. This paper evaluates the performance and limitations of a novel technique capa ...

de Soria-Santacruz, M.; Li, W.; Thorne, R.; Ma, Q.; Bortnik, J.; Ni, B.; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

YEAR: 2015     DOI: 10.1002/2015JA021148

Plasmaspheric Hiss; Van Allen Probes; wave-particle interactions; Waves global model

Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Validation with conjunctive Van Allen Probes observations

Plasmaspheric hiss plays an important role in controlling the overall structure and dynamics of the Earth\textquoterights radiation belts. The interaction of plasmaspheric hiss with radiation belt electrons is commonly evaluated using diffusion codes, which rely on statistical models of wave observations that may not accurately reproduce the instantaneous global wave distribution, or the limited in-situ satellite wave measurements from satellites. This paper evaluates the performance and limitations of a novel technique capa ...

de Soria-Santacruz, M.; Li, W.; Thorne, R.; Ma, Q.; Bortnik, J.; Ni, B.; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

YEAR: 2015     DOI: 10.1002/2015JA021148

Plasmaspheric Hiss; Van Allen Probes; wave-particle interactions; Waves global model

A novel data assimilation technique for the plasmasphere

We present a novel technique for imaging and data assimilation of the topside ionosphere and plasmasphere. The methodology is based upon the 3 dimensional variational technique (3DVAR), where an empirical background model is utilized. However, to prevent non-physical vertical variation in density estimates, we devise statistical methods to enforce a roughness penalty in the traditional 3DVAR optimization. The upward looking total electron content (TEC) observations from the Global Positioning System (GPS) receiver onboard Co ...

Nikoukar, Romina; Bust, Gary; Murr, David;

YEAR: 2015     DOI: 10.1002/2015JA021455

GPS Techniques; Plasmasphere Data assimilation; Plasmasphere Imaging; Regularization

Resonant scattering of outer zone relativistic electrons by multiband EMIC waves and resultant electron loss time scales

To improve our understanding of the role of electromagnetic ion cyclotron (EMIC) waves in radiation belt electron dynamics, we perform a comprehensive analysis of EMIC wave-induced resonant scattering of outer zone relativistic (>0.5 MeV) electrons and resultant electron loss time scales with respect to EMIC wave band, L shell, and wave normal angle model. The results demonstrate that while H+-band EMIC waves dominate the scattering losses of ~1\textendash4 MeV outer zone relativistic electrons, it is He+-band and O+-band wa ...

Ni, Binbin; Cao, Xing; Zou, Zhengyang; Zhou, Chen; Gu, Xudong; Bortnik, Jacob; Zhang, Jichun; Fu, Song; Zhao, Zhengyu; Shi, Run; Xie, Lun;

YEAR: 2015     DOI: 10.1002/2015JA021466

electron loss time scales; EMIC waves; outer radiation belt; relativistic electrons; resonant wave-particle interactions

Resonant scattering of outer zone relativistic electrons by multiband EMIC waves and resultant electron loss time scales

To improve our understanding of the role of electromagnetic ion cyclotron (EMIC) waves in radiation belt electron dynamics, we perform a comprehensive analysis of EMIC wave-induced resonant scattering of outer zone relativistic (>0.5 MeV) electrons and resultant electron loss time scales with respect to EMIC wave band, L shell, and wave normal angle model. The results demonstrate that while H+-band EMIC waves dominate the scattering losses of ~1\textendash4 MeV outer zone relativistic electrons, it is He+-band and O+-band wa ...

Ni, Binbin; Cao, Xing; Zou, Zhengyang; Zhou, Chen; Gu, Xudong; Bortnik, Jacob; Zhang, Jichun; Fu, Song; Zhao, Zhengyu; Shi, Run; Xie, Lun;

YEAR: 2015     DOI: 10.1002/2015JA021466

electron loss time scales; EMIC waves; outer radiation belt; relativistic electrons; resonant wave-particle interactions

Solar wind conditions leading to efficient radiation belt electron acceleration: A superposed epoch analysis

Determining preferential solar wind conditions leading to efficient radiation belt electron acceleration is crucial for predicting radiation belt electron dynamics. Using Van Allen Probes electron observations (>1 MeV) from 2012 to 2015, we identify a number of efficient and inefficient acceleration events separately to perform a superposed epoch analysis of the corresponding solar wind parameters and geomagnetic indices. By directly comparing efficient and inefficient acceleration events, we clearly show that prolonged sout ...

Li, W.; Thorne, R.; Bortnik, J.; Baker, D.; Reeves, G.; Kanekal, S.; Spence, H.; Green, J.;

YEAR: 2015     DOI: 10.1002/2015GL065342

Chorus wave; Electron acceleration; solar wind conditions; Van Allen Probes

Identification of the source of quasiperiodic VLF emissions using ground-based and Van Allen Probes satellite observations

We report on simultaneous spacecraft and ground-based observations of quasiperiodic VLF emissions and related energetic-electron dynamics. Quasiperiodic emissions in the frequency range 2\textendash6 kHz were observed during a substorm on 25 January 2013 by Van Allen Probe-A and a ground-based station in the Northern Finland. The spacecraft detected the VLF signals near the geomagnetic equator in the night sector at L = 3.0\textendash4.2 when it was inside the plasmasphere. During the satellite motion toward higher latitudes ...

Titova, E.; Kozelov, B.; Demekhov, A.; Manninen, J.; Santolik, O.; Kletzing, C.; Reeves, G.;

YEAR: 2015     DOI: 10.1002/grl.v42.1510.1002/2015GL064911

energetic electrons; quasiperiodic emissions; Van Allen Probes; VLF waves

Source and Seed Populations for Relativistic Electrons: Their Roles in Radiation Belt Changes

Strong enhancements of outer Van Allen belt electrons have been shown to have a clear dependence on solar wind speed and on the duration of southward interplanetary magnetic field. However, individual case study analyses also have demonstrated that many geomagnetic storms produce little in the way of outer belt enhancements and, in fact, may produce substantial losses of relativistic electrons. In this study, focused upon a key period in August-September 2014, we use GOES geostationary orbit electron flux data and Van Allen ...

Jaynes, A.N.; Baker, D.N.; Singer, H.J.; Rodriguez, J.V.; Loto\textquoterightaniu, T.M.; Ali, A.; Elkington, S.R.; Li, X.; Kanekal, S.G.; Fennell, J.F.; Li, W.; Thorne, R.M.; Kletzing, C.A.; Spence, H.E.; Reeves, G.D.;

YEAR: 2015     DOI: 10.1002/2015JA021234

Radiation belts; relativistic electrons; substorms; ULF waves; Van Allen Probes; VLF waves

Dense plasma and Kelvin-Helmholtz waves at Earth\textquoterights dayside magnetopause

Spacecraft observations of boundary waves at the dayside terrestrial magnetopause and their ground-based signatures are presented. Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft measured boundary waves at the magnetopause while ground-based HF radar measured corresponding signatures in the ionosphere indicating a large-scale response and tailward propagating waves. The properties of the oscillations are consistent with linear phase Kelvin-Helmholtz waves along the magnetopause boundar ...

Walsh, B.; Thomas, E.; Hwang, K.-J.; Baker, J.; Ruohoniemi, J.; Bonnell, J.;

YEAR: 2015     DOI: 10.1002/2015JA021014

Kelvin-Helmholtz; magnetopause

Nonlinear Bounce Resonances between Magnetosonic Waves and Equatorially Mirroring Electrons

Equatorially mirroring energetic electrons pose an interesting scientific problem, since they generally cannot resonate with any known plasma waves and hence cannot be scattered down to lower pitch angles. Observationally it is well known that the fluxof these equatorial particles does not simply continue to build up indefinitely, and so a mechanism must necessarily exist that transports these particles from a equatorial pitch angle of 90 degrees down to lower values. However this mechanism has not been uniquely identified y ...

Chen, Lunjin; Maldonado, Armando; Bortnik, Jacob; Thorne, Richard; Li, Jinxing; Dai, Lei; Zhan, Xiaoya;

YEAR: 2015     DOI: 10.1002/2015JA021174

bounce resonance; equatorioal noise; magnetosonic waves; nonlinear; Radiation belt; wave particle interaction

Statistical properties of plasmaspheric hiss derived from Van Allen Probes data and their Effects on radiation belt electron dynamics

Plasmaspheric hiss is known to play an important role in controlling the overall structure and dynamics of radiation belt electrons inside the plasmasphere. Using newly available Van Allen Probes wave data, which provide excellent coverage in the entire inner magnetosphere, we evaluate the global distribution of the hiss wave frequency spectrum and wave intensity for different levels of substorm activity. Our statistical results show that observed hiss peak frequencies are generally lower than the commonly adopted value (~55 ...

Li, W.; Ma, Q.; Thorne, R.; Bortnik, J.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Nishimura, Y.;

YEAR: 2015     DOI: 10.1002/2015JA021048

hiss diffusion coefficient; hiss frequency spectrum; Plasmaspheric Hiss; Van Allen Probes

Statistical properties of plasmaspheric hiss derived from Van Allen Probes data and their Effects on radiation belt electron dynamics

Plasmaspheric hiss is known to play an important role in controlling the overall structure and dynamics of radiation belt electrons inside the plasmasphere. Using newly available Van Allen Probes wave data, which provide excellent coverage in the entire inner magnetosphere, we evaluate the global distribution of the hiss wave frequency spectrum and wave intensity for different levels of substorm activity. Our statistical results show that observed hiss peak frequencies are generally lower than the commonly adopted value (~55 ...

Li, W.; Ma, Q.; Thorne, R.; Bortnik, J.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Nishimura, Y.;

YEAR: 2015     DOI: 10.1002/2015JA021048

hiss diffusion coefficient; hiss frequency spectrum; Plasmaspheric Hiss; Van Allen Probes

Variability of the pitch angle distribution of radiation belt ultra-relativistic electrons during and following intense geomagnetic storms: Van Allen Probes observations

Fifteen months of pitch angle resolved Van Allen Probes REPT measurements of differential electron flux are analyzed to investigate the characteristic variability of the pitch angle distribution (PAD) of radiation belt ultra-relativistic (>2 MeV) electrons during storm conditions and during the long-term post-storm decay. By modeling the ultra-relativistic electron pitch angle distribution as sinn α, where α is the equatorial pitch angle, we examine the spatio-temporal variations of the n-value. The results show that in ge ...

Ni, Binbin; Zou, Zhengyang; Gu, Xudong; Zhou, Chen; Thorne, Richard; Bortnik, Jacob; Shi, Run; Zhao, Zhengyu; Baker, Daniel; Kanekal, Shrikhanth; Spence, Harlan; Reeves, Geoffrey; Li, Xinlin;

YEAR: 2015     DOI: 10.1002/2015JA021065

adiation belt ultra-relativistic electrons; decay timescales; Geomagnetic storms; Pitch angle distribution; resonant wave-particle interactions; Van Allen Probes

Variability of the pitch angle distribution of radiation belt ultra-relativistic electrons during and following intense geomagnetic storms: Van Allen Probes observations

Fifteen months of pitch angle resolved Van Allen Probes REPT measurements of differential electron flux are analyzed to investigate the characteristic variability of the pitch angle distribution (PAD) of radiation belt ultra-relativistic (>2 MeV) electrons during storm conditions and during the long-term post-storm decay. By modeling the ultra-relativistic electron pitch angle distribution as sinn α, where α is the equatorial pitch angle, we examine the spatio-temporal variations of the n-value. The results show that in ge ...

Ni, Binbin; Zou, Zhengyang; Gu, Xudong; Zhou, Chen; Thorne, Richard; Bortnik, Jacob; Shi, Run; Zhao, Zhengyu; Baker, Daniel; Kanekal, Shrikhanth; Spence, Harlan; Reeves, Geoffrey; Li, Xinlin;

YEAR: 2015     DOI: 10.1002/2015JA021065

adiation belt ultra-relativistic electrons; decay timescales; Geomagnetic storms; Pitch angle distribution; resonant wave-particle interactions; Van Allen Probes

Azimuthal flow bursts in the Inner Plasma Sheet and Possible Connection with SAPS and Plasma Sheet Earthward Flow Bursts

We have combined radar observations and auroral images obtained during the PFISR Ion Neutral Observations in the Thermosphere campaign to show the common occurrence of westward moving, localized auroral brightenings near the auroral equatorward boundary and to show their association with azimuthally moving flow bursts near or within the SAPS region. These results indicate that the SAPS region, rather than consisting of relatively stable proton precipitation and westward flows, can have rapidly varying flows, with speeds vary ...

Lyons, L.; Nishimura, Y.; Gallardo-Lacourt, B.; Nicolls, M.; Chen, S.; Hampton, D.; Bristow, W.; Ruohoniemi, J.; Nishitani, N.; Donovan, E.; Angelopoulos, V.;

YEAR: 2015     DOI: 10.1002/2015JA021023

aurora; convection; Flow bursts; plasma sheet; SAPS; streamers

Azimuthal flow bursts in the Inner Plasma Sheet and Possible Connection with SAPS and Plasma Sheet Earthward Flow Bursts

We have combined radar observations and auroral images obtained during the PFISR Ion Neutral Observations in the Thermosphere campaign to show the common occurrence of westward moving, localized auroral brightenings near the auroral equatorward boundary and to show their association with azimuthally moving flow bursts near or within the SAPS region. These results indicate that the SAPS region, rather than consisting of relatively stable proton precipitation and westward flows, can have rapidly varying flows, with speeds vary ...

Lyons, L.; Nishimura, Y.; Gallardo-Lacourt, B.; Nicolls, M.; Chen, S.; Hampton, D.; Bristow, W.; Ruohoniemi, J.; Nishitani, N.; Donovan, E.; Angelopoulos, V.;

YEAR: 2015     DOI: 10.1002/2015JA021023

aurora; convection; Flow bursts; plasma sheet; SAPS; streamers

Azimuthal flow bursts in the Inner Plasma Sheet and Possible Connection with SAPS and Plasma Sheet Earthward Flow Bursts

We have combined radar observations and auroral images obtained during the PFISR Ion Neutral Observations in the Thermosphere campaign to show the common occurrence of westward moving, localized auroral brightenings near the auroral equatorward boundary and to show their association with azimuthally moving flow bursts near or within the SAPS region. These results indicate that the SAPS region, rather than consisting of relatively stable proton precipitation and westward flows, can have rapidly varying flows, with speeds vary ...

Lyons, L.; Nishimura, Y.; Gallardo-Lacourt, B.; Nicolls, M.; Chen, S.; Hampton, D.; Bristow, W.; Ruohoniemi, J.; Nishitani, N.; Donovan, E.; Angelopoulos, V.;

YEAR: 2015     DOI: 10.1002/2015JA021023

aurora; convection; Flow bursts; plasma sheet; SAPS; streamers

Azimuthal flow bursts in the Inner Plasma Sheet and Possible Connection with SAPS and Plasma Sheet Earthward Flow Bursts

We have combined radar observations and auroral images obtained during the PFISR Ion Neutral Observations in the Thermosphere campaign to show the common occurrence of westward moving, localized auroral brightenings near the auroral equatorward boundary and to show their association with azimuthally moving flow bursts near or within the SAPS region. These results indicate that the SAPS region, rather than consisting of relatively stable proton precipitation and westward flows, can have rapidly varying flows, with speeds vary ...

Lyons, L.; Nishimura, Y.; Gallardo-Lacourt, B.; Nicolls, M.; Chen, S.; Hampton, D.; Bristow, W.; Ruohoniemi, J.; Nishitani, N.; Donovan, E.; Angelopoulos, V.;

YEAR: 2015     DOI: 10.1002/2015JA021023

aurora; convection; Flow bursts; plasma sheet; SAPS; streamers

Direct observations of the full Dungey convection cycle in the polar ionosphere for southward interplanetary magnetic field conditions

Tracking the formation and full evolution of polar cap ionization patches in the polar ionosphere, we directly observe the full Dungey convection cycle for southward interplanetary magnetic field (IMF) conditions. This enables us to study how the Dungey cycle influences the patches\textquoteright evolution. The patches were initially segmented from the dayside storm enhanced density plume (SED) at the equatorward edge of the cusp, by the expansion and contraction of the polar cap boundary (PCB) due to pulsed dayside magnetop ...

Zhang, Q.; Lockwood, M.; Foster, J.; Zhang, S.; Zhang, B.; McCrea, I.; Moen, J.; Lester, M.; Ruohoniemi, Michael;

YEAR: 2015     DOI: 10.1002/2015JA021172

Dungey convection cycle; EISCAT radar; GPS TEC; polar cap patches

Equatorial noise emissions with quasiperiodic modulation of wave intensity

Equatorial noise (EN) emissions are electromagnetic wave events at frequencies between the proton cyclotron frequency and the lower hybrid frequency observed in the equatorial region of the inner magnetosphere. They propagate nearly perpendicular to the ambient magnetic field, and they exhibit a harmonic line structure characteristic of the proton cyclotron frequency in the source region. However, they were generally believed to be continuous in time. We investigate more than 2000 EN events observed by the Spatio-Temporal An ...

emec, F.; Santolik, O.; a, Hrb\; Pickett, J.; Cornilleau-Wehrlin, N.;

YEAR: 2015     DOI: 10.1002/2014JA020816

equatorial noise; magnetosonic waves; quasiperiodic modulation

Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Technique sensitivity analysis

A novel technique capable of inferring wave amplitudes from low-altitude electron measurements from the POES spacecraft has been previously proposed to construct a global dynamic model of chorus and plasmaspheric hiss waves. In this paper we focus on plasmaspheric hiss, which is an incoherent broadband emission that plays a dominant role in the loss of energetic electrons from the inner magnetosphere. We analyze the sensitivity of the POES technique to different inputs used to infer the hiss wave amplitudes during three conj ...

de Soria-Santacruz, M.; Li, W.; Thorne, R.; Ma, Q.; Bortnik, J.; Ni, B.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.D.; Blake, J.; Fennell, J.;

YEAR: 2015     DOI: 10.1002/2014JA020941

Plasmaspheric Hiss; POES technique; Van Allen Probes; Waves global model

Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Technique sensitivity analysis

A novel technique capable of inferring wave amplitudes from low-altitude electron measurements from the POES spacecraft has been previously proposed to construct a global dynamic model of chorus and plasmaspheric hiss waves. In this paper we focus on plasmaspheric hiss, which is an incoherent broadband emission that plays a dominant role in the loss of energetic electrons from the inner magnetosphere. We analyze the sensitivity of the POES technique to different inputs used to infer the hiss wave amplitudes during three conj ...

de Soria-Santacruz, M.; Li, W.; Thorne, R.; Ma, Q.; Bortnik, J.; Ni, B.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.D.; Blake, J.; Fennell, J.;

YEAR: 2015     DOI: 10.1002/2014JA020941

Plasmaspheric Hiss; POES technique; Van Allen Probes; Waves global model

High-energy radiation belt electrons from CRAND

A calculation of the inner radiation belt electron source from cosmic ray albedo neutron decay (CRAND) is described. High-energy electrons are included by Lorentz-transforming the β decay spectrum from the neutron rest frame to the Earth\textquoterights rest frame and combining with the known high-energy albedo neutron energy spectrum. Balancing the electron source with energy loss to atmospheric neutral atoms and plasma, and with a decay lifetime representative of plasma wave scattering, then provides an estimate of trappe ...

Selesnick, R.;

YEAR: 2015     DOI: 10.1002/2014JA020963

inner radiation; electron source from cosmic ray albedo neutron decay

Intensities and spatiotemporal variability of equatorial noise emissions observed by the Cluster spacecraft

Equatorial noise (EN) emissions are electromagnetic waves observed in the equatorial region of the inner magnetosphere at frequencies between the proton cyclotron frequency and the lower hybrid frequency. We present the analysis of 2229 EN events identified in the Spatio-Temporal Analysis of Field Fluctuations (STAFF) experiment data of the Cluster spacecraft during the years 2001\textendash2010. EN emissions are distinguished using the polarization analysis, and their intensity is determined based on the evaluation of the P ...

emec, F.; Santolik, O.; a, Hrb\; Cornilleau-Wehrlin, N.;

YEAR: 2015     DOI: 10.1002/2014JA020814

equatorial noise; magnetosonic waves

The global context of the 14 November, 2012 storm event

From 2 to 5 UT on 14 November, 2012, the Van Allen Probes observed repeated particle flux dropouts during the main phase of a geomagnetic storm as the satellites traversed the post-midnight to dawnside inner magnetosphere. Each flux dropout corresponded to an abrupt change in the magnetic topology, i.e., from a more dipolar configuration to a configuration with magnetic field lines stretched in the dawn-dusk direction. Geosynchronous GOES spacecraft located in the dusk and near-midnight sectors and the LANL constellation wit ...

Hwang, K.-J.; Sibeck, D.; Fok, M.-C.; Zheng, Y.; Nishimura, Y.; Lee, J.-J.; Glocer, A.; Partamies, N.; Singer, H.; Reeves, G.; Mitchell, D.; Kletzing, C.; Onsager, T.;

YEAR: 2015     DOI: 10.1002/2014JA020826

Van Allen Probes

Modeling inward diffusion and slow decay of energetic electrons in the Earth\textquoterights outer radiation belt

A new 3D diffusion code is used to investigate the inward intrusion and slow decay of energetic radiation belt electrons (>0.5 MeV) observed by the Van Allen Probes during a 10-day quiet period in March 2013. During the inward transport the peak differential electron fluxes decreased by approximately an order of magnitude at various energies. Our 3D radiation belt simulation including radial diffusion and pitch angle and energy diffusion by plasmaspheric hiss and Electromagnetic Ion Cyclotron (EMIC) waves reproduces the esse ...

Ma, Q.; Li, W.; Thorne, R.; Ni, B.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Reeves, G.; Henderson, M.; Spence, H.; Baker, D.; Blake, J.; Fennell, J.; Claudepierre, S.; Angelopoulos, V.;

YEAR: 2015     DOI: 10.1002/2014GL062977

pitch angle scattering; radiation belts modeling; Van Allen Probes; Van Allen Probes observations

Modeling sub-auroral polarization streams (SAPS) during the March 17, 2013 storm

The sub-auroral polarization streams (SAPS) are one of the most important features in representing magnetosphere-ionosphere coupling processes. In this study, we use a state-of-the-art modeling framework that couples an inner magnetospheric ring current model RAM-SCB with a global MHD model BATS-R-US and an ionospheric potential solver to study the SAPS that occurred during the March 17, 2013 storm event as well as to assess the modeling capability. Both ionospheric and magnetospheric signatures associated with SAPS are anal ...

Yu, Yiqun; Jordanova, Vania; Zou, Shasha; Heelis, Roderick; Ruohoniemi, Mike; Wygant, John;

YEAR: 2015     DOI: 10.1002/2014JA020371

sub-auroral polarization streams; Van Allen Probes

Spatial structure and temporal evolution of energetic particle injections in the inner magnetosphere during the 14 July 2013 substorm event.

Recent results by the Van Allen Probes mission showed that the occurrence of energetic ion injections inside geosynchronous orbit could be very frequent throughout the main phase of a geomagnetic storm. Understanding, therefore, the formation and evolution of energetic particle injections is critical in order to quantify their effect in the inner magnetosphere. We present a case study of a substorm event that occurred during a weak storm (Dst ~ - 40 nT) on 14 July 2013. Van Allen Probe B, inside geosynchronous orbit, observe ...

Gkioulidou, Matina; Ohtani, S.; Mitchell, D.; Ukhorskiy, A.; Reeves, G.; Turner, D.; Gjerloev, J.; e, Nos\; Koga, K.; Rodriguez, J.; Lanzerotti, L.;

YEAR: 2015     DOI: 10.1002/2014JA020872

inner magnetosphere; Van Allen Probes

Systematic analysis of occurrence of equatorial noise emissions using 10 years of data from the Cluster mission

We report results of a systematic analysis of equatorial noise (EN) emissions which are also known as fast magnetosonic waves. EN occurs in the vicinity of the geomagnetic equator at frequencies between the local proton cyclotron frequency and the lower hybrid frequency. Our analysis is based on the data collected by the Spatio-Temporal Analysis of Field Fluctuations\textendashSpectrum Analyzer instruments on board the four Cluster spacecraft. The data set covers the period from January 2001 to December 2010. We have develop ...

a, Hrb\; Santolik, O.; emec, F.; a, Mac\; Cornilleau-Wehrlin, N.;

YEAR: 2015     DOI: 10.1002/2014JA020268

equatorial noise; magnetosonic waves; plasmasphere; Radiation belts

Ecohydrologic role of solar radiation on landscape evolution

Solar radiation has a clear signature on the spatial organization of ecohydrologic fluxes, vegetation patterns and dynamics, and landscape morphology in semiarid ecosystems. Existing landscape evolution models (LEMs) do not explicitly consider spatially explicit solar radiation as model forcing. Here, we improve an existing LEM to represent coupled processes of energy, water, and sediment balance for semiarid fluvial catchments. To ground model predictions, a study site is selected in central New Mexico where hillslope aspec ...

Yetemen, Omer; Istanbulluoglu, Erkan; Flores-Cervantes, Homero; Vivoni, Enrique; Bras, Rafael;

YEAR: 2015     DOI: 10.1002/wrcr.v51.210.1002/2014WR016169

catchment evolution; ecohydrology; geomorphology; landscape evolution; solar radiation; vegetation dynamics

First Evidence for Chorus at a Large Geocentric Distance as a Source of Plasmaspheric Hiss: Coordinated THEMIS and Van Allen Probes Observation

Recent ray tracing suggests that plasmaspheric hiss can originate from chorus observed outside of the plasmapause. Although a few individual events have been reported to support this mechanism, the number of reported conjugate events is still very limited. Using coordinated observations between THEMIS and Van Allen Probes, we report on an interesting event, where chorus was observed at a large L-shell (~9.8), different from previously reported events at L < 6, but still exhibited a remarkable correlation with hiss observed i ...

Li, W.; Chen, L.; Bortnik, J.; Thorne, R.; Angelopoulos, V.; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

YEAR: 2015     DOI: 10.1002/2014GL062832

Chorus; hiss; wave propagation; Van Allen Probes

Upper limit on the inner radiation belt MeV electron Intensity

No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (10s of MeV to GeV). The inner belt proton flux level, however, is relatively stable, thus for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) on board Colorado Student Space Weather Experiment (CSSWE) CubeSat, in a low Earth orbit, clearly demonstrate that there e ...

Li, X.; Selesnick, R.; Baker, D.; Jaynes, A.; Kanekal, S.; Schiller, Q.; Blum, L.; Fennell, J.; Blake, J.;

YEAR: 2015     DOI: 10.1002/2014JA020777

Van Allen Probes

2014

Evolution of relativistic outer belt electrons during an extended quiescent period

To effectively study steady loss due to hiss-driven precipitation of relativistic electrons in the outer radiation belt, it is useful to isolate this loss by studying a time of relatively quiet geomagnetic activity. We present a case of initial enhancement and slow, steady decay of 700 keV - 2 MeV electron populations in the outer radiation belt during an extended quiescent period from ~15 December 2012 - 13 January 2013. We incorporate particle measurements from a constellation of satellites, including the Colorado Student ...

Jaynes, A.; Li, X.; Schiller, Q.; Blum, L.; Tu, W.; Turner, D.; Ni, B.; Bortnik, J.; Baker, D.; Kanekal, S.; Blake, J.; Wygant, J.;

YEAR: 2014     DOI: 10.1002/2014JA020125

electron lifetime; hiss waves; pitch angle scattering; precipitation loss; Radiation belts; Van Allen Probes

Evolution of relativistic outer belt electrons during an extended quiescent period

To effectively study steady loss due to hiss-driven precipitation of relativistic electrons in the outer radiation belt, it is useful to isolate this loss by studying a time of relatively quiet geomagnetic activity. We present a case of initial enhancement and slow, steady decay of 700 keV - 2 MeV electron populations in the outer radiation belt during an extended quiescent period from ~15 December 2012 - 13 January 2013. We incorporate particle measurements from a constellation of satellites, including the Colorado Student ...

Jaynes, A.; Li, X.; Schiller, Q.; Blum, L.; Tu, W.; Turner, D.; Ni, B.; Bortnik, J.; Baker, D.; Kanekal, S.; Blake, J.; Wygant, J.;

YEAR: 2014     DOI: 10.1002/2014JA020125

electron lifetime; hiss waves; pitch angle scattering; precipitation loss; Radiation belts; Van Allen Probes

Electron lifetimes from narrowband wave-particle interactions within the plasmasphere

This paper is devoted to the systematic study of electron lifetimes from narrowband wave-particle interactions within the plasmasphere. It relies on a new formulation of the bounce-averaged quasi-linear pitch angle diffusion coefficients parameterized by a single frequency, ω, and wave normal angle, θ. We first show that the diffusion coefficients scale with ω/Ωce, where Ωce is the equatorial electron gyrofrequency, and that maximal pitch angle diffusion occurs along the line α0 = π/2\textendashθ, where α0 is the eq ...

Ripoll, J.-F.; Albert, J.; Cunningham, G.;

YEAR: 2014     DOI: 10.1002/2014JA020217

DSX; electron; narrowband; plasmasphere; wave-particle interactions

Initial Measurements of O-ion and He-ion Decay Rates Observed from the Van Allen Probes RBSPICE Instrument

H-ion (~45-keV to ~600-keV), He-ion (~65-keV to ~520-keV), and O-ion (~140-keV to ~1130-keV) integral flux measurements, from the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument aboard the Van Allan Probes spacecraft B, are reported. These abundance data form a cohesive picture of ring current ions during the first nine months of measurements. Furthermore, the data presented herein are used to show injection characteristics via the He-ion/H-ion abundance ratio and the O-ion/H-ion abundance ratio. O ...

Gerrard, Andrew; Lanzerotti, Louis; Gkioulidou, Matina; Mitchell, Donald; Manweiler, Jerry; Bortnik, Jacob; Keika, Kunihiro;

YEAR: 2014     DOI: 10.1002/2014JA020374

inner magnetosphere; ion decay rates; Spacecraft measurements; Van Allen Probes



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