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Found 4151 entries in the Bibliography.
Showing entries from 3551 through 3600
| 2014 |
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Storm time observations of plasmasphere erosion flux in the magnetosphere and ionosphere Plasmasphere erosion carries cold dense plasma of ionospheric origin in a storm-enhanced density plume extending from dusk toward and through the noontime cusp and dayside magnetopause and back across polar latitudes in a polar tongue of ionization. We examine dusk sector (20 MLT) plasmasphere erosion during the 17 March 2013 storm (Dst ~ -130 nT) using simultaneous, magnetically aligned direct sunward ion flux observations at high altitude by Van Allen Probes RBSP-A (at ~3.0 Re) and at ionospheric heights (~840 km) by DMSP F-18. Plasma erosion occurs at both high and low altitudes where the subauroral polarization stream flow overlaps the outer plasmasphere. At ~20 UT, RBSP-A observed ~1.2E12 m-2 s-1 erosion flux, while DMSP F-18 observed ~2E13 m-2 s-1 sunward flux. We find close similarities at high and low altitudes between the erosion plume in both invariant latitude spatial extent and plasma characteristics. Foster, J.; Erickson, P.; Coster, A.; Thaller, S.; Tao, J.; Wygant, J.; Bonnell, J; Published by: Geophysical Research Letters Published on: 02/2014 YEAR: 2014 DOI: 10.1002/2013GL059124 |
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Storm time observations of plasmasphere erosion flux in the magnetosphere and ionosphere Plasmasphere erosion carries cold dense plasma of ionospheric origin in a storm-enhanced density plume extending from dusk toward and through the noontime cusp and dayside magnetopause and back across polar latitudes in a polar tongue of ionization. We examine dusk sector (20 MLT) plasmasphere erosion during the 17 March 2013 storm (Dst ~ -130 nT) using simultaneous, magnetically aligned direct sunward ion flux observations at high altitude by Van Allen Probes RBSP-A (at ~3.0 Re) and at ionospheric heights (~840 km) by DMSP F-18. Plasma erosion occurs at both high and low altitudes where the subauroral polarization stream flow overlaps the outer plasmasphere. At ~20 UT, RBSP-A observed ~1.2E12 m-2 s-1 erosion flux, while DMSP F-18 observed ~2E13 m-2 s-1 sunward flux. We find close similarities at high and low altitudes between the erosion plume in both invariant latitude spatial extent and plasma characteristics. Foster, J.; Erickson, P.; Coster, A.; Thaller, S.; Tao, J.; Wygant, J.; Bonnell, J; Published by: Geophysical Research Letters Published on: 02/2014 YEAR: 2014 DOI: 10.1002/2013GL059124 |
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Storm time observations of plasmasphere erosion flux in the magnetosphere and ionosphere Plasmasphere erosion carries cold dense plasma of ionospheric origin in a storm-enhanced density plume extending from dusk toward and through the noontime cusp and dayside magnetopause and back across polar latitudes in a polar tongue of ionization. We examine dusk sector (20 MLT) plasmasphere erosion during the 17 March 2013 storm (Dst ~ -130 nT) using simultaneous, magnetically aligned direct sunward ion flux observations at high altitude by Van Allen Probes RBSP-A (at ~3.0 Re) and at ionospheric heights (~840 km) by DMSP F-18. Plasma erosion occurs at both high and low altitudes where the subauroral polarization stream flow overlaps the outer plasmasphere. At ~20 UT, RBSP-A observed ~1.2E12 m-2 s-1 erosion flux, while DMSP F-18 observed ~2E13 m-2 s-1 sunward flux. We find close similarities at high and low altitudes between the erosion plume in both invariant latitude spatial extent and plasma characteristics. Foster, J.; Erickson, P.; Coster, A.; Thaller, S.; Tao, J.; Wygant, J.; Bonnell, J; Published by: Geophysical Research Letters Published on: 02/2014 YEAR: 2014 DOI: 10.1002/2013GL059124 |
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Storm time observations of plasmasphere erosion flux in the magnetosphere and ionosphere Plasmasphere erosion carries cold dense plasma of ionospheric origin in a storm-enhanced density plume extending from dusk toward and through the noontime cusp and dayside magnetopause and back across polar latitudes in a polar tongue of ionization. We examine dusk sector (20 MLT) plasmasphere erosion during the 17 March 2013 storm (Dst ~ -130 nT) using simultaneous, magnetically aligned direct sunward ion flux observations at high altitude by Van Allen Probes RBSP-A (at ~3.0 Re) and at ionospheric heights (~840 km) by DMSP F-18. Plasma erosion occurs at both high and low altitudes where the subauroral polarization stream flow overlaps the outer plasmasphere. At ~20 UT, RBSP-A observed ~1.2E12 m-2 s-1 erosion flux, while DMSP F-18 observed ~2E13 m-2 s-1 sunward flux. We find close similarities at high and low altitudes between the erosion plume in both invariant latitude spatial extent and plasma characteristics. Foster, J.; Erickson, P.; Coster, A.; Thaller, S.; Tao, J.; Wygant, J.; Bonnell, J; Published by: Geophysical Research Letters Published on: 02/2014 YEAR: 2014 DOI: 10.1002/2013GL059124 |
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Storm time observations of plasmasphere erosion flux in the magnetosphere and ionosphere Plasmasphere erosion carries cold dense plasma of ionospheric origin in a storm-enhanced density plume extending from dusk toward and through the noontime cusp and dayside magnetopause and back across polar latitudes in a polar tongue of ionization. We examine dusk sector (20 MLT) plasmasphere erosion during the 17 March 2013 storm (Dst ~ -130 nT) using simultaneous, magnetically aligned direct sunward ion flux observations at high altitude by Van Allen Probes RBSP-A (at ~3.0 Re) and at ionospheric heights (~840 km) by DMSP F-18. Plasma erosion occurs at both high and low altitudes where the subauroral polarization stream flow overlaps the outer plasmasphere. At ~20 UT, RBSP-A observed ~1.2E12 m-2 s-1 erosion flux, while DMSP F-18 observed ~2E13 m-2 s-1 sunward flux. We find close similarities at high and low altitudes between the erosion plume in both invariant latitude spatial extent and plasma characteristics. Foster, J.; Erickson, P.; Coster, A.; Thaller, S.; Tao, J.; Wygant, J.; Bonnell, J; Published by: Geophysical Research Letters Published on: 02/2014 YEAR: 2014 DOI: 10.1002/2013GL059124 |
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Testing a two-loop pattern of the substorm current wedge (SCW2L) Recent quantitative testing of the classical (region 1 sense) substorm current wedge (SCI) model revealed systematic discrepancies between the observed and predicted amplitudes, which suggested us to include additional region 2 sense currents (R2 loop) earthward of the dipolarized region (SCW2L model). Here we discuss alternative circuit geometries of the 3-D substorm current system and interpret observations of the magnetic field dipolarizations made between 6.6RE and 11RE, to quantitatively investigate the SCW2L model parameters. During two cases of a dipole-like magnetotail configuration, the dipolarization/injection front fortuitously stopped at r ~ 9RE for the entire duration of ~ 30 min long SCW-related dipolarization within a unique, radially distributed multispacecraft constellation, which allowed us to determine the locations and total currents of both SCW2L loops. In addition, we analyzed the dipolarization amplitudes in events, simultaneously observed at 6.6RE, 11RE and at colatitudes under a wide range of magnetograph conditions. We infer that the ratio I2/I1 varies in the range 0.2 to 0.6 (median value 0.4) and that the equatorial part of the R2 current loop stays at r>6.6RE in the case of a dipole-like field geometry (BZ0>75 nT at 6.6RE prior to the onset), but it is located at r<6.6RE in the case of a stretched magnetic field configuration (with BZ0<60 nT). Since the ground midlatitude perturbations are sensitive to the combined effect of the R1 and R2 sense current loops with the net current roughly equal to I1-I2, the ratio I2/I1 becomes an important issue when attempting to monitor the current disruption intensity from ground observations. Sergeev, V.; Nikolaev, A.; Tsyganenko, N.; Angelopoulos, V.; Runov, A.; Singer, H.; Yang, J.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2014 YEAR: 2014 DOI: 10.1002/2013JA019629 |
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Testing a two-loop pattern of the substorm current wedge (SCW2L) Recent quantitative testing of the classical (region 1 sense) substorm current wedge (SCI) model revealed systematic discrepancies between the observed and predicted amplitudes, which suggested us to include additional region 2 sense currents (R2 loop) earthward of the dipolarized region (SCW2L model). Here we discuss alternative circuit geometries of the 3-D substorm current system and interpret observations of the magnetic field dipolarizations made between 6.6RE and 11RE, to quantitatively investigate the SCW2L model parameters. During two cases of a dipole-like magnetotail configuration, the dipolarization/injection front fortuitously stopped at r ~ 9RE for the entire duration of ~ 30 min long SCW-related dipolarization within a unique, radially distributed multispacecraft constellation, which allowed us to determine the locations and total currents of both SCW2L loops. In addition, we analyzed the dipolarization amplitudes in events, simultaneously observed at 6.6RE, 11RE and at colatitudes under a wide range of magnetograph conditions. We infer that the ratio I2/I1 varies in the range 0.2 to 0.6 (median value 0.4) and that the equatorial part of the R2 current loop stays at r>6.6RE in the case of a dipole-like field geometry (BZ0>75 nT at 6.6RE prior to the onset), but it is located at r<6.6RE in the case of a stretched magnetic field configuration (with BZ0<60 nT). Since the ground midlatitude perturbations are sensitive to the combined effect of the R1 and R2 sense current loops with the net current roughly equal to I1-I2, the ratio I2/I1 becomes an important issue when attempting to monitor the current disruption intensity from ground observations. Sergeev, V.; Nikolaev, A.; Tsyganenko, N.; Angelopoulos, V.; Runov, A.; Singer, H.; Yang, J.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2014 YEAR: 2014 DOI: 10.1002/2013JA019629 |
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Testing a two-loop pattern of the substorm current wedge (SCW2L) Recent quantitative testing of the classical (region 1 sense) substorm current wedge (SCI) model revealed systematic discrepancies between the observed and predicted amplitudes, which suggested us to include additional region 2 sense currents (R2 loop) earthward of the dipolarized region (SCW2L model). Here we discuss alternative circuit geometries of the 3-D substorm current system and interpret observations of the magnetic field dipolarizations made between 6.6RE and 11RE, to quantitatively investigate the SCW2L model parameters. During two cases of a dipole-like magnetotail configuration, the dipolarization/injection front fortuitously stopped at r ~ 9RE for the entire duration of ~ 30 min long SCW-related dipolarization within a unique, radially distributed multispacecraft constellation, which allowed us to determine the locations and total currents of both SCW2L loops. In addition, we analyzed the dipolarization amplitudes in events, simultaneously observed at 6.6RE, 11RE and at colatitudes under a wide range of magnetograph conditions. We infer that the ratio I2/I1 varies in the range 0.2 to 0.6 (median value 0.4) and that the equatorial part of the R2 current loop stays at r>6.6RE in the case of a dipole-like field geometry (BZ0>75 nT at 6.6RE prior to the onset), but it is located at r<6.6RE in the case of a stretched magnetic field configuration (with BZ0<60 nT). Since the ground midlatitude perturbations are sensitive to the combined effect of the R1 and R2 sense current loops with the net current roughly equal to I1-I2, the ratio I2/I1 becomes an important issue when attempting to monitor the current disruption intensity from ground observations. Sergeev, V.; Nikolaev, A.; Tsyganenko, N.; Angelopoulos, V.; Runov, A.; Singer, H.; Yang, J.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2014 YEAR: 2014 DOI: 10.1002/2013JA019629 |
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Testing a two-loop pattern of the substorm current wedge (SCW2L) Recent quantitative testing of the classical (region 1 sense) substorm current wedge (SCI) model revealed systematic discrepancies between the observed and predicted amplitudes, which suggested us to include additional region 2 sense currents (R2 loop) earthward of the dipolarized region (SCW2L model). Here we discuss alternative circuit geometries of the 3-D substorm current system and interpret observations of the magnetic field dipolarizations made between 6.6RE and 11RE, to quantitatively investigate the SCW2L model parameters. During two cases of a dipole-like magnetotail configuration, the dipolarization/injection front fortuitously stopped at r ~ 9RE for the entire duration of ~ 30 min long SCW-related dipolarization within a unique, radially distributed multispacecraft constellation, which allowed us to determine the locations and total currents of both SCW2L loops. In addition, we analyzed the dipolarization amplitudes in events, simultaneously observed at 6.6RE, 11RE and at colatitudes under a wide range of magnetograph conditions. We infer that the ratio I2/I1 varies in the range 0.2 to 0.6 (median value 0.4) and that the equatorial part of the R2 current loop stays at r>6.6RE in the case of a dipole-like field geometry (BZ0>75 nT at 6.6RE prior to the onset), but it is located at r<6.6RE in the case of a stretched magnetic field configuration (with BZ0<60 nT). Since the ground midlatitude perturbations are sensitive to the combined effect of the R1 and R2 sense current loops with the net current roughly equal to I1-I2, the ratio I2/I1 becomes an important issue when attempting to monitor the current disruption intensity from ground observations. Sergeev, V.; Nikolaev, A.; Tsyganenko, N.; Angelopoulos, V.; Runov, A.; Singer, H.; Yang, J.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2014 YEAR: 2014 DOI: 10.1002/2013JA019629 |
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Testing a two-loop pattern of the substorm current wedge (SCW2L) Recent quantitative testing of the classical (region 1 sense) substorm current wedge (SCI) model revealed systematic discrepancies between the observed and predicted amplitudes, which suggested us to include additional region 2 sense currents (R2 loop) earthward of the dipolarized region (SCW2L model). Here we discuss alternative circuit geometries of the 3-D substorm current system and interpret observations of the magnetic field dipolarizations made between 6.6RE and 11RE, to quantitatively investigate the SCW2L model parameters. During two cases of a dipole-like magnetotail configuration, the dipolarization/injection front fortuitously stopped at r ~ 9RE for the entire duration of ~ 30 min long SCW-related dipolarization within a unique, radially distributed multispacecraft constellation, which allowed us to determine the locations and total currents of both SCW2L loops. In addition, we analyzed the dipolarization amplitudes in events, simultaneously observed at 6.6RE, 11RE and at colatitudes under a wide range of magnetograph conditions. We infer that the ratio I2/I1 varies in the range 0.2 to 0.6 (median value 0.4) and that the equatorial part of the R2 current loop stays at r>6.6RE in the case of a dipole-like field geometry (BZ0>75 nT at 6.6RE prior to the onset), but it is located at r<6.6RE in the case of a stretched magnetic field configuration (with BZ0<60 nT). Since the ground midlatitude perturbations are sensitive to the combined effect of the R1 and R2 sense current loops with the net current roughly equal to I1-I2, the ratio I2/I1 becomes an important issue when attempting to monitor the current disruption intensity from ground observations. Sergeev, V.; Nikolaev, A.; Tsyganenko, N.; Angelopoulos, V.; Runov, A.; Singer, H.; Yang, J.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2014 YEAR: 2014 DOI: 10.1002/2013JA019629 |
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Chorus waves and spacecraft potential fluctuations: Evidence for wave-enhanced photoelectron escape Chorus waves are important for electron energization and loss in Earth\textquoterights radiation belts and inner magnetosphere. Because the amplitude and spatial distribution of chorus waves can be strongly influenced by plasma density fluctuations and spacecraft floating potential can be a diagnostic of plasma density, the relationship between measured potential and chorus waves is examined using Van Allen Probes data. While measured potential and chorus wave electric fields correlate strongly, potential fluctuation properties are found not to be consistent with plasma density fluctuations on the timescales of individual chorus wave packets. Instead, potential fluctuations are consistent with enhanced photoelectron escape driven by chorus wave electric fields. Enhanced photoelectron escape may result in potential fluctuations of the spacecraft body, the electric field probes, or both, depending on the ambient plasma and magnetic field environment. These results differ significantly from prior interpretations of the correspondence between measured potential and wave electric fields. Malaspina, D.; Ergun, R.; Sturner, A.; Wygant, J.; Bonnell, J; Breneman, A.; Kersten, K.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058769 |
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Chorus waves and spacecraft potential fluctuations: Evidence for wave-enhanced photoelectron escape Chorus waves are important for electron energization and loss in Earth\textquoterights radiation belts and inner magnetosphere. Because the amplitude and spatial distribution of chorus waves can be strongly influenced by plasma density fluctuations and spacecraft floating potential can be a diagnostic of plasma density, the relationship between measured potential and chorus waves is examined using Van Allen Probes data. While measured potential and chorus wave electric fields correlate strongly, potential fluctuation properties are found not to be consistent with plasma density fluctuations on the timescales of individual chorus wave packets. Instead, potential fluctuations are consistent with enhanced photoelectron escape driven by chorus wave electric fields. Enhanced photoelectron escape may result in potential fluctuations of the spacecraft body, the electric field probes, or both, depending on the ambient plasma and magnetic field environment. These results differ significantly from prior interpretations of the correspondence between measured potential and wave electric fields. Malaspina, D.; Ergun, R.; Sturner, A.; Wygant, J.; Bonnell, J; Breneman, A.; Kersten, K.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058769 |
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Chorus waves and spacecraft potential fluctuations: Evidence for wave-enhanced photoelectron escape Chorus waves are important for electron energization and loss in Earth\textquoterights radiation belts and inner magnetosphere. Because the amplitude and spatial distribution of chorus waves can be strongly influenced by plasma density fluctuations and spacecraft floating potential can be a diagnostic of plasma density, the relationship between measured potential and chorus waves is examined using Van Allen Probes data. While measured potential and chorus wave electric fields correlate strongly, potential fluctuation properties are found not to be consistent with plasma density fluctuations on the timescales of individual chorus wave packets. Instead, potential fluctuations are consistent with enhanced photoelectron escape driven by chorus wave electric fields. Enhanced photoelectron escape may result in potential fluctuations of the spacecraft body, the electric field probes, or both, depending on the ambient plasma and magnetic field environment. These results differ significantly from prior interpretations of the correspondence between measured potential and wave electric fields. Malaspina, D.; Ergun, R.; Sturner, A.; Wygant, J.; Bonnell, J; Breneman, A.; Kersten, K.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058769 |
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Chorus waves and spacecraft potential fluctuations: Evidence for wave-enhanced photoelectron escape Chorus waves are important for electron energization and loss in Earth\textquoterights radiation belts and inner magnetosphere. Because the amplitude and spatial distribution of chorus waves can be strongly influenced by plasma density fluctuations and spacecraft floating potential can be a diagnostic of plasma density, the relationship between measured potential and chorus waves is examined using Van Allen Probes data. While measured potential and chorus wave electric fields correlate strongly, potential fluctuation properties are found not to be consistent with plasma density fluctuations on the timescales of individual chorus wave packets. Instead, potential fluctuations are consistent with enhanced photoelectron escape driven by chorus wave electric fields. Enhanced photoelectron escape may result in potential fluctuations of the spacecraft body, the electric field probes, or both, depending on the ambient plasma and magnetic field environment. These results differ significantly from prior interpretations of the correspondence between measured potential and wave electric fields. Malaspina, D.; Ergun, R.; Sturner, A.; Wygant, J.; Bonnell, J; Breneman, A.; Kersten, K.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058769 |
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Chorus waves and spacecraft potential fluctuations: Evidence for wave-enhanced photoelectron escape Chorus waves are important for electron energization and loss in Earth\textquoterights radiation belts and inner magnetosphere. Because the amplitude and spatial distribution of chorus waves can be strongly influenced by plasma density fluctuations and spacecraft floating potential can be a diagnostic of plasma density, the relationship between measured potential and chorus waves is examined using Van Allen Probes data. While measured potential and chorus wave electric fields correlate strongly, potential fluctuation properties are found not to be consistent with plasma density fluctuations on the timescales of individual chorus wave packets. Instead, potential fluctuations are consistent with enhanced photoelectron escape driven by chorus wave electric fields. Enhanced photoelectron escape may result in potential fluctuations of the spacecraft body, the electric field probes, or both, depending on the ambient plasma and magnetic field environment. These results differ significantly from prior interpretations of the correspondence between measured potential and wave electric fields. Malaspina, D.; Ergun, R.; Sturner, A.; Wygant, J.; Bonnell, J; Breneman, A.; Kersten, K.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058769 |
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Using data from NASA\textquoterights Van Allen Probes, we have identified a synchronized exponential decay of electron flux in the outer zone, near L* = 5.0. Exponential decays strongly indicate the presence of a pure eigenmode of a diffusion operator acting in the synchronized dimension(s). The decay has a time scale of about 4 days with no dependence on pitch angle. While flux at nearby energies and L* is also decaying exponentially, the decay time varies in those dimensions. This suggests the primary decay mechanism is elastic pitch angle scattering, which itself depends on energy and L*. We invert the shape of the observed eigenmode to obtain an approximate shape of the pitch angle diffusion coefficient and show excellent agreement with diffusion by plasmaspheric hiss. Our results suggest that empirically derived eigenmodes provide a powerful diagnostic of the dynamic processes behind exponential decays. O\textquoterightBrien, T.; Claudepierre, S.; Blake, J.; Fennell, J.; Clemmons, J.; Roeder, J.; Spence, H.; Reeves, G.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058713 |
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Using data from NASA\textquoterights Van Allen Probes, we have identified a synchronized exponential decay of electron flux in the outer zone, near L* = 5.0. Exponential decays strongly indicate the presence of a pure eigenmode of a diffusion operator acting in the synchronized dimension(s). The decay has a time scale of about 4 days with no dependence on pitch angle. While flux at nearby energies and L* is also decaying exponentially, the decay time varies in those dimensions. This suggests the primary decay mechanism is elastic pitch angle scattering, which itself depends on energy and L*. We invert the shape of the observed eigenmode to obtain an approximate shape of the pitch angle diffusion coefficient and show excellent agreement with diffusion by plasmaspheric hiss. Our results suggest that empirically derived eigenmodes provide a powerful diagnostic of the dynamic processes behind exponential decays. O\textquoterightBrien, T.; Claudepierre, S.; Blake, J.; Fennell, J.; Clemmons, J.; Roeder, J.; Spence, H.; Reeves, G.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058713 |
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Using data from NASA\textquoterights Van Allen Probes, we have identified a synchronized exponential decay of electron flux in the outer zone, near L* = 5.0. Exponential decays strongly indicate the presence of a pure eigenmode of a diffusion operator acting in the synchronized dimension(s). The decay has a time scale of about 4 days with no dependence on pitch angle. While flux at nearby energies and L* is also decaying exponentially, the decay time varies in those dimensions. This suggests the primary decay mechanism is elastic pitch angle scattering, which itself depends on energy and L*. We invert the shape of the observed eigenmode to obtain an approximate shape of the pitch angle diffusion coefficient and show excellent agreement with diffusion by plasmaspheric hiss. Our results suggest that empirically derived eigenmodes provide a powerful diagnostic of the dynamic processes behind exponential decays. O\textquoterightBrien, T.; Claudepierre, S.; Blake, J.; Fennell, J.; Clemmons, J.; Roeder, J.; Spence, H.; Reeves, G.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058713 |
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Using data from NASA\textquoterights Van Allen Probes, we have identified a synchronized exponential decay of electron flux in the outer zone, near L* = 5.0. Exponential decays strongly indicate the presence of a pure eigenmode of a diffusion operator acting in the synchronized dimension(s). The decay has a time scale of about 4 days with no dependence on pitch angle. While flux at nearby energies and L* is also decaying exponentially, the decay time varies in those dimensions. This suggests the primary decay mechanism is elastic pitch angle scattering, which itself depends on energy and L*. We invert the shape of the observed eigenmode to obtain an approximate shape of the pitch angle diffusion coefficient and show excellent agreement with diffusion by plasmaspheric hiss. Our results suggest that empirically derived eigenmodes provide a powerful diagnostic of the dynamic processes behind exponential decays. O\textquoterightBrien, T.; Claudepierre, S.; Blake, J.; Fennell, J.; Clemmons, J.; Roeder, J.; Spence, H.; Reeves, G.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058713 |
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Using data from NASA\textquoterights Van Allen Probes, we have identified a synchronized exponential decay of electron flux in the outer zone, near L* = 5.0. Exponential decays strongly indicate the presence of a pure eigenmode of a diffusion operator acting in the synchronized dimension(s). The decay has a time scale of about 4 days with no dependence on pitch angle. While flux at nearby energies and L* is also decaying exponentially, the decay time varies in those dimensions. This suggests the primary decay mechanism is elastic pitch angle scattering, which itself depends on energy and L*. We invert the shape of the observed eigenmode to obtain an approximate shape of the pitch angle diffusion coefficient and show excellent agreement with diffusion by plasmaspheric hiss. Our results suggest that empirically derived eigenmodes provide a powerful diagnostic of the dynamic processes behind exponential decays. O\textquoterightBrien, T.; Claudepierre, S.; Blake, J.; Fennell, J.; Clemmons, J.; Roeder, J.; Spence, H.; Reeves, G.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058713 |
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Using data from NASA\textquoterights Van Allen Probes, we have identified a synchronized exponential decay of electron flux in the outer zone, near L* = 5.0. Exponential decays strongly indicate the presence of a pure eigenmode of a diffusion operator acting in the synchronized dimension(s). The decay has a time scale of about 4 days with no dependence on pitch angle. While flux at nearby energies and L* is also decaying exponentially, the decay time varies in those dimensions. This suggests the primary decay mechanism is elastic pitch angle scattering, which itself depends on energy and L*. We invert the shape of the observed eigenmode to obtain an approximate shape of the pitch angle diffusion coefficient and show excellent agreement with diffusion by plasmaspheric hiss. Our results suggest that empirically derived eigenmodes provide a powerful diagnostic of the dynamic processes behind exponential decays. O\textquoterightBrien, T.; Claudepierre, S.; Blake, J.; Fennell, J.; Clemmons, J.; Roeder, J.; Spence, H.; Reeves, G.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058713 |
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Using data from NASA\textquoterights Van Allen Probes, we have identified a synchronized exponential decay of electron flux in the outer zone, near L* = 5.0. Exponential decays strongly indicate the presence of a pure eigenmode of a diffusion operator acting in the synchronized dimension(s). The decay has a time scale of about 4 days with no dependence on pitch angle. While flux at nearby energies and L* is also decaying exponentially, the decay time varies in those dimensions. This suggests the primary decay mechanism is elastic pitch angle scattering, which itself depends on energy and L*. We invert the shape of the observed eigenmode to obtain an approximate shape of the pitch angle diffusion coefficient and show excellent agreement with diffusion by plasmaspheric hiss. Our results suggest that empirically derived eigenmodes provide a powerful diagnostic of the dynamic processes behind exponential decays. O\textquoterightBrien, T.; Claudepierre, S.; Blake, J.; Fennell, J.; Clemmons, J.; Roeder, J.; Spence, H.; Reeves, G.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058713 |
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Using data from NASA\textquoterights Van Allen Probes, we have identified a synchronized exponential decay of electron flux in the outer zone, near L* = 5.0. Exponential decays strongly indicate the presence of a pure eigenmode of a diffusion operator acting in the synchronized dimension(s). The decay has a time scale of about 4 days with no dependence on pitch angle. While flux at nearby energies and L* is also decaying exponentially, the decay time varies in those dimensions. This suggests the primary decay mechanism is elastic pitch angle scattering, which itself depends on energy and L*. We invert the shape of the observed eigenmode to obtain an approximate shape of the pitch angle diffusion coefficient and show excellent agreement with diffusion by plasmaspheric hiss. Our results suggest that empirically derived eigenmodes provide a powerful diagnostic of the dynamic processes behind exponential decays. O\textquoterightBrien, T.; Claudepierre, S.; Blake, J.; Fennell, J.; Clemmons, J.; Roeder, J.; Spence, H.; Reeves, G.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058713 |
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Using data from NASA\textquoterights Van Allen Probes, we have identified a synchronized exponential decay of electron flux in the outer zone, near L* = 5.0. Exponential decays strongly indicate the presence of a pure eigenmode of a diffusion operator acting in the synchronized dimension(s). The decay has a time scale of about 4 days with no dependence on pitch angle. While flux at nearby energies and L* is also decaying exponentially, the decay time varies in those dimensions. This suggests the primary decay mechanism is elastic pitch angle scattering, which itself depends on energy and L*. We invert the shape of the observed eigenmode to obtain an approximate shape of the pitch angle diffusion coefficient and show excellent agreement with diffusion by plasmaspheric hiss. Our results suggest that empirically derived eigenmodes provide a powerful diagnostic of the dynamic processes behind exponential decays. O\textquoterightBrien, T.; Claudepierre, S.; Blake, J.; Fennell, J.; Clemmons, J.; Roeder, J.; Spence, H.; Reeves, G.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058713 |
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Fine structure of large-amplitude chorus wave packets Whistler mode chorus waves in the outer Van Allen belt can have consequences for acceleration of relativistic electrons through wave-particle interactions. New multicomponent waveform measurements have been collected by the Van Allen Probes Electric and Magnetic Field Instrument Suite and Integrated Science\textquoterights Waves instrument. We detect fine structure of chorus elements with peak instantaneous amplitudes of a few hundred picotesla but exceptionally reaching up to 3 nT, i.e., more than 1\% of the background magnetic field. The wave vector direction turns by a few tens of degrees within a single chorus element but also within its subpackets. Our analysis of a significant number of subpackets embedded in rising frequency elements shows that amplitudes of their peaks tend to decrease with frequency. The wave vector is quasi-parallel to the background magnetic field for large-amplitude subpackets, while it turns away from this direction when the amplitudes are weaker. Santolik, O.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Bounds, S.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058889 |
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Generation of electromagnetic waves in the very low frequency band by velocity gradient It is shown that a magnetized plasma layer with a velocity gradient in the flow perpendicular to the ambient magnetic field is unstable to waves in the Very Low Frequency band that spans the ion and electron gyrofrequencies. The waves are formally electromagnetic. However, depending on wave vector k⎯⎯=kc/ωpe (normalized by the electron skin depth) and the obliqueness, k⊥/k|| , where k⊥,|||| are wave vectors perpendicular and parallel to the magnetic field, the waves are closer to electrostatic in nature when k⎯⎯>>1 and k⊥>>k|| and electromagnetic otherwise. Inhomogeneous transverse flows are generated in plasma that contains a static electric field perpendicular to the magnetic field, a configuration that may naturally arise in the boundary layer between plasmas of different characteristics. Ganguli, G.; Tejero, E.; Crabtree, C.; Amatucci, W.; Rudakov, L.; Published by: Physics of Plasmas Published on: 01/2014 YEAR: 2014 DOI: 10.1063/1.4862032 |
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Generation of electromagnetic waves in the very low frequency band by velocity gradient It is shown that a magnetized plasma layer with a velocity gradient in the flow perpendicular to the ambient magnetic field is unstable to waves in the Very Low Frequency band that spans the ion and electron gyrofrequencies. The waves are formally electromagnetic. However, depending on wave vector k⎯⎯=kc/ωpe (normalized by the electron skin depth) and the obliqueness, k⊥/k|| , where k⊥,|||| are wave vectors perpendicular and parallel to the magnetic field, the waves are closer to electrostatic in nature when k⎯⎯>>1 and k⊥>>k|| and electromagnetic otherwise. Inhomogeneous transverse flows are generated in plasma that contains a static electric field perpendicular to the magnetic field, a configuration that may naturally arise in the boundary layer between plasmas of different characteristics. Ganguli, G.; Tejero, E.; Crabtree, C.; Amatucci, W.; Rudakov, L.; Published by: Physics of Plasmas Published on: 01/2014 YEAR: 2014 DOI: 10.1063/1.4862032 |
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Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes Storm time electron radiation belt dynamics have been widely investigated for many years. Here we present a rarely reported nonstorm time event of electron radiation belt evolution observed by the Van Allen Probes during 21\textendash24 February 2013. Within 2 days, a new belt centering around L=5.8 formed and gradually merged with the original outer belt, with the enhancement of relativistic electron fluxes by a factor of up to 50. Strong chorus waves (with power spectral density up to 10-4nT2/Hz) occurred in the region L>5. Taking into account the local acceleration driven by these chorus waves, the two-dimensional STEERB can approximately reproduce the observed energy spectrums at the center of the new belt. These results clearly illustrate the complexity of electron radiation belt behaviors and the importance of chorus-driven local acceleration even during the nonstorm times. Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; He, Zhaoguo; Zhu, Hui; Zhang, Min; Shen, Chao; Wang, Yuming; Wang, Shui; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Funsten, H.; Blake, J.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058912 |
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Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes Storm time electron radiation belt dynamics have been widely investigated for many years. Here we present a rarely reported nonstorm time event of electron radiation belt evolution observed by the Van Allen Probes during 21\textendash24 February 2013. Within 2 days, a new belt centering around L=5.8 formed and gradually merged with the original outer belt, with the enhancement of relativistic electron fluxes by a factor of up to 50. Strong chorus waves (with power spectral density up to 10-4nT2/Hz) occurred in the region L>5. Taking into account the local acceleration driven by these chorus waves, the two-dimensional STEERB can approximately reproduce the observed energy spectrums at the center of the new belt. These results clearly illustrate the complexity of electron radiation belt behaviors and the importance of chorus-driven local acceleration even during the nonstorm times. Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; He, Zhaoguo; Zhu, Hui; Zhang, Min; Shen, Chao; Wang, Yuming; Wang, Shui; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Funsten, H.; Blake, J.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058912 |
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Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes Storm time electron radiation belt dynamics have been widely investigated for many years. Here we present a rarely reported nonstorm time event of electron radiation belt evolution observed by the Van Allen Probes during 21\textendash24 February 2013. Within 2 days, a new belt centering around L=5.8 formed and gradually merged with the original outer belt, with the enhancement of relativistic electron fluxes by a factor of up to 50. Strong chorus waves (with power spectral density up to 10-4nT2/Hz) occurred in the region L>5. Taking into account the local acceleration driven by these chorus waves, the two-dimensional STEERB can approximately reproduce the observed energy spectrums at the center of the new belt. These results clearly illustrate the complexity of electron radiation belt behaviors and the importance of chorus-driven local acceleration even during the nonstorm times. Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; He, Zhaoguo; Zhu, Hui; Zhang, Min; Shen, Chao; Wang, Yuming; Wang, Shui; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Funsten, H.; Blake, J.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058912 |
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Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes Storm time electron radiation belt dynamics have been widely investigated for many years. Here we present a rarely reported nonstorm time event of electron radiation belt evolution observed by the Van Allen Probes during 21\textendash24 February 2013. Within 2 days, a new belt centering around L=5.8 formed and gradually merged with the original outer belt, with the enhancement of relativistic electron fluxes by a factor of up to 50. Strong chorus waves (with power spectral density up to 10-4nT2/Hz) occurred in the region L>5. Taking into account the local acceleration driven by these chorus waves, the two-dimensional STEERB can approximately reproduce the observed energy spectrums at the center of the new belt. These results clearly illustrate the complexity of electron radiation belt behaviors and the importance of chorus-driven local acceleration even during the nonstorm times. Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; He, Zhaoguo; Zhu, Hui; Zhang, Min; Shen, Chao; Wang, Yuming; Wang, Shui; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Funsten, H.; Blake, J.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058912 |
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Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes Storm time electron radiation belt dynamics have been widely investigated for many years. Here we present a rarely reported nonstorm time event of electron radiation belt evolution observed by the Van Allen Probes during 21\textendash24 February 2013. Within 2 days, a new belt centering around L=5.8 formed and gradually merged with the original outer belt, with the enhancement of relativistic electron fluxes by a factor of up to 50. Strong chorus waves (with power spectral density up to 10-4nT2/Hz) occurred in the region L>5. Taking into account the local acceleration driven by these chorus waves, the two-dimensional STEERB can approximately reproduce the observed energy spectrums at the center of the new belt. These results clearly illustrate the complexity of electron radiation belt behaviors and the importance of chorus-driven local acceleration even during the nonstorm times. Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; He, Zhaoguo; Zhu, Hui; Zhang, Min; Shen, Chao; Wang, Yuming; Wang, Shui; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Funsten, H.; Blake, J.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058912 |
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Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes Storm time electron radiation belt dynamics have been widely investigated for many years. Here we present a rarely reported nonstorm time event of electron radiation belt evolution observed by the Van Allen Probes during 21\textendash24 February 2013. Within 2 days, a new belt centering around L=5.8 formed and gradually merged with the original outer belt, with the enhancement of relativistic electron fluxes by a factor of up to 50. Strong chorus waves (with power spectral density up to 10-4nT2/Hz) occurred in the region L>5. Taking into account the local acceleration driven by these chorus waves, the two-dimensional STEERB can approximately reproduce the observed energy spectrums at the center of the new belt. These results clearly illustrate the complexity of electron radiation belt behaviors and the importance of chorus-driven local acceleration even during the nonstorm times. Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; He, Zhaoguo; Zhu, Hui; Zhang, Min; Shen, Chao; Wang, Yuming; Wang, Shui; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Funsten, H.; Blake, J.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058912 |
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Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes Storm time electron radiation belt dynamics have been widely investigated for many years. Here we present a rarely reported nonstorm time event of electron radiation belt evolution observed by the Van Allen Probes during 21\textendash24 February 2013. Within 2 days, a new belt centering around L=5.8 formed and gradually merged with the original outer belt, with the enhancement of relativistic electron fluxes by a factor of up to 50. Strong chorus waves (with power spectral density up to 10-4nT2/Hz) occurred in the region L>5. Taking into account the local acceleration driven by these chorus waves, the two-dimensional STEERB can approximately reproduce the observed energy spectrums at the center of the new belt. These results clearly illustrate the complexity of electron radiation belt behaviors and the importance of chorus-driven local acceleration even during the nonstorm times. Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; He, Zhaoguo; Zhu, Hui; Zhang, Min; Shen, Chao; Wang, Yuming; Wang, Shui; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Funsten, H.; Blake, J.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058912 |
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Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes Storm time electron radiation belt dynamics have been widely investigated for many years. Here we present a rarely reported nonstorm time event of electron radiation belt evolution observed by the Van Allen Probes during 21\textendash24 February 2013. Within 2 days, a new belt centering around L=5.8 formed and gradually merged with the original outer belt, with the enhancement of relativistic electron fluxes by a factor of up to 50. Strong chorus waves (with power spectral density up to 10-4nT2/Hz) occurred in the region L>5. Taking into account the local acceleration driven by these chorus waves, the two-dimensional STEERB can approximately reproduce the observed energy spectrums at the center of the new belt. These results clearly illustrate the complexity of electron radiation belt behaviors and the importance of chorus-driven local acceleration even during the nonstorm times. Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; He, Zhaoguo; Zhu, Hui; Zhang, Min; Shen, Chao; Wang, Yuming; Wang, Shui; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Funsten, H.; Blake, J.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058912 |
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Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes Storm time electron radiation belt dynamics have been widely investigated for many years. Here we present a rarely reported nonstorm time event of electron radiation belt evolution observed by the Van Allen Probes during 21\textendash24 February 2013. Within 2 days, a new belt centering around L=5.8 formed and gradually merged with the original outer belt, with the enhancement of relativistic electron fluxes by a factor of up to 50. Strong chorus waves (with power spectral density up to 10-4nT2/Hz) occurred in the region L>5. Taking into account the local acceleration driven by these chorus waves, the two-dimensional STEERB can approximately reproduce the observed energy spectrums at the center of the new belt. These results clearly illustrate the complexity of electron radiation belt behaviors and the importance of chorus-driven local acceleration even during the nonstorm times. Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; He, Zhaoguo; Zhu, Hui; Zhang, Min; Shen, Chao; Wang, Yuming; Wang, Shui; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Funsten, H.; Blake, J.; Baker, D.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058912 |
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A nonstorm time enhancement of relativistic electrons in the outer radiation belt Despite the lack of a geomagnetic storm (based on the Dst index), relativistic electron fluxes were enhanced over 2.5 orders of magnitude in the outer radiation belt in 13 h on 13\textendash14 January 2013. The unusual enhancement was observed by Magnetic Electron Ion Spectrometer (MagEIS), onboard the Van Allen Probes; Relativistic Electron and Proton Telescope Integrated Little Experiment, onboard the Colorado Student Space Weather Experiment; and Solid State Telescope, onboard Time History of Events and Macroscale Interactions during Substorms (THEMIS). Analyses of MagEIS phase space density (PSD) profiles show a positive outward radial gradient from 4 < L < 5.5. However, THEMIS observations show a peak in PSD outside of the Van Allen Probes\textquoteright apogee, which suggest a very interesting scenario: wave-particle interactions causing a PSD peak at ~ L* = 5.5 from where the electrons are then rapidly transported radially inward. This letter demonstrates, for the first time in detail, that geomagnetic storms are not necessary for causing dramatic enhancements in the outer radiation belt. Schiller, Quintin; Li, Xinlin; Blum, Lauren; Tu, Weichao; Turner, Drew; Blake, J.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058485 |
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A nonstorm time enhancement of relativistic electrons in the outer radiation belt Despite the lack of a geomagnetic storm (based on the Dst index), relativistic electron fluxes were enhanced over 2.5 orders of magnitude in the outer radiation belt in 13 h on 13\textendash14 January 2013. The unusual enhancement was observed by Magnetic Electron Ion Spectrometer (MagEIS), onboard the Van Allen Probes; Relativistic Electron and Proton Telescope Integrated Little Experiment, onboard the Colorado Student Space Weather Experiment; and Solid State Telescope, onboard Time History of Events and Macroscale Interactions during Substorms (THEMIS). Analyses of MagEIS phase space density (PSD) profiles show a positive outward radial gradient from 4 < L < 5.5. However, THEMIS observations show a peak in PSD outside of the Van Allen Probes\textquoteright apogee, which suggest a very interesting scenario: wave-particle interactions causing a PSD peak at ~ L* = 5.5 from where the electrons are then rapidly transported radially inward. This letter demonstrates, for the first time in detail, that geomagnetic storms are not necessary for causing dramatic enhancements in the outer radiation belt. Schiller, Quintin; Li, Xinlin; Blum, Lauren; Tu, Weichao; Turner, Drew; Blake, J.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058485 |
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A nonstorm time enhancement of relativistic electrons in the outer radiation belt Despite the lack of a geomagnetic storm (based on the Dst index), relativistic electron fluxes were enhanced over 2.5 orders of magnitude in the outer radiation belt in 13 h on 13\textendash14 January 2013. The unusual enhancement was observed by Magnetic Electron Ion Spectrometer (MagEIS), onboard the Van Allen Probes; Relativistic Electron and Proton Telescope Integrated Little Experiment, onboard the Colorado Student Space Weather Experiment; and Solid State Telescope, onboard Time History of Events and Macroscale Interactions during Substorms (THEMIS). Analyses of MagEIS phase space density (PSD) profiles show a positive outward radial gradient from 4 < L < 5.5. However, THEMIS observations show a peak in PSD outside of the Van Allen Probes\textquoteright apogee, which suggest a very interesting scenario: wave-particle interactions causing a PSD peak at ~ L* = 5.5 from where the electrons are then rapidly transported radially inward. This letter demonstrates, for the first time in detail, that geomagnetic storms are not necessary for causing dramatic enhancements in the outer radiation belt. Schiller, Quintin; Li, Xinlin; Blum, Lauren; Tu, Weichao; Turner, Drew; Blake, J.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058485 |
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Observations of kinetic scale field line resonances We identify electromagnetic field variations from the Van Allen Probes which have the properties of Doppler shifted kinetic scale Alfv\ enic field line resonances. These variations are observed during injections of energetic plasmas into the inner magnetosphere. These waves have scale sizes perpendicular to the magnetic field which are determined to be of the order of an ion gyro-radius (ρi) and less. Cross-spectral analysis of the electric and magnetic fields reveals phase transitions at frequencies correlated with enhancements and depressions in the ratio of the electric and magnetic fields. Modeling shows that these observations are consistent with the excitation of field-line resonances over a broad range of wave numbers perpendicular to the magnetic field (k⊥) extending to k⊥ρi >> 1. The amplitude of these waves is such that E/Bo ≳ Ωi/k⊥ (E, Bo, and Ωi are the wave amplitude, background field strength, and ion gyro-frequency, respectively) leading to ion demagnetization and acceleration for multiple transitions through the wave potential. Chaston, Christopher; Bonnell, J; Wygant, John; Mozer, Forrest; Bale, Stuart; Kersten, Kris; Breneman, Aaron; Kletzing, Craig; Kurth, William; Hospodarsky, George; Smith, Charles; MacDonald, Elizabeth; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058507 |
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Observations of kinetic scale field line resonances We identify electromagnetic field variations from the Van Allen Probes which have the properties of Doppler shifted kinetic scale Alfv\ enic field line resonances. These variations are observed during injections of energetic plasmas into the inner magnetosphere. These waves have scale sizes perpendicular to the magnetic field which are determined to be of the order of an ion gyro-radius (ρi) and less. Cross-spectral analysis of the electric and magnetic fields reveals phase transitions at frequencies correlated with enhancements and depressions in the ratio of the electric and magnetic fields. Modeling shows that these observations are consistent with the excitation of field-line resonances over a broad range of wave numbers perpendicular to the magnetic field (k⊥) extending to k⊥ρi >> 1. The amplitude of these waves is such that E/Bo ≳ Ωi/k⊥ (E, Bo, and Ωi are the wave amplitude, background field strength, and ion gyro-frequency, respectively) leading to ion demagnetization and acceleration for multiple transitions through the wave potential. Chaston, Christopher; Bonnell, J; Wygant, John; Mozer, Forrest; Bale, Stuart; Kersten, Kris; Breneman, Aaron; Kletzing, Craig; Kurth, William; Hospodarsky, George; Smith, Charles; MacDonald, Elizabeth; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058507 |
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Observations of kinetic scale field line resonances We identify electromagnetic field variations from the Van Allen Probes which have the properties of Doppler shifted kinetic scale Alfv\ enic field line resonances. These variations are observed during injections of energetic plasmas into the inner magnetosphere. These waves have scale sizes perpendicular to the magnetic field which are determined to be of the order of an ion gyro-radius (ρi) and less. Cross-spectral analysis of the electric and magnetic fields reveals phase transitions at frequencies correlated with enhancements and depressions in the ratio of the electric and magnetic fields. Modeling shows that these observations are consistent with the excitation of field-line resonances over a broad range of wave numbers perpendicular to the magnetic field (k⊥) extending to k⊥ρi >> 1. The amplitude of these waves is such that E/Bo ≳ Ωi/k⊥ (E, Bo, and Ωi are the wave amplitude, background field strength, and ion gyro-frequency, respectively) leading to ion demagnetization and acceleration for multiple transitions through the wave potential. Chaston, Christopher; Bonnell, J; Wygant, John; Mozer, Forrest; Bale, Stuart; Kersten, Kris; Breneman, Aaron; Kletzing, Craig; Kurth, William; Hospodarsky, George; Smith, Charles; MacDonald, Elizabeth; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058507 |
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Observations of kinetic scale field line resonances We identify electromagnetic field variations from the Van Allen Probes which have the properties of Doppler shifted kinetic scale Alfv\ enic field line resonances. These variations are observed during injections of energetic plasmas into the inner magnetosphere. These waves have scale sizes perpendicular to the magnetic field which are determined to be of the order of an ion gyro-radius (ρi) and less. Cross-spectral analysis of the electric and magnetic fields reveals phase transitions at frequencies correlated with enhancements and depressions in the ratio of the electric and magnetic fields. Modeling shows that these observations are consistent with the excitation of field-line resonances over a broad range of wave numbers perpendicular to the magnetic field (k⊥) extending to k⊥ρi >> 1. The amplitude of these waves is such that E/Bo ≳ Ωi/k⊥ (E, Bo, and Ωi are the wave amplitude, background field strength, and ion gyro-frequency, respectively) leading to ion demagnetization and acceleration for multiple transitions through the wave potential. Chaston, Christopher; Bonnell, J; Wygant, John; Mozer, Forrest; Bale, Stuart; Kersten, Kris; Breneman, Aaron; Kletzing, Craig; Kurth, William; Hospodarsky, George; Smith, Charles; MacDonald, Elizabeth; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058507 |
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Observations of kinetic scale field line resonances We identify electromagnetic field variations from the Van Allen Probes which have the properties of Doppler shifted kinetic scale Alfv\ enic field line resonances. These variations are observed during injections of energetic plasmas into the inner magnetosphere. These waves have scale sizes perpendicular to the magnetic field which are determined to be of the order of an ion gyro-radius (ρi) and less. Cross-spectral analysis of the electric and magnetic fields reveals phase transitions at frequencies correlated with enhancements and depressions in the ratio of the electric and magnetic fields. Modeling shows that these observations are consistent with the excitation of field-line resonances over a broad range of wave numbers perpendicular to the magnetic field (k⊥) extending to k⊥ρi >> 1. The amplitude of these waves is such that E/Bo ≳ Ωi/k⊥ (E, Bo, and Ωi are the wave amplitude, background field strength, and ion gyro-frequency, respectively) leading to ion demagnetization and acceleration for multiple transitions through the wave potential. Chaston, Christopher; Bonnell, J; Wygant, John; Mozer, Forrest; Bale, Stuart; Kersten, Kris; Breneman, Aaron; Kletzing, Craig; Kurth, William; Hospodarsky, George; Smith, Charles; MacDonald, Elizabeth; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058507 |
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Observations of kinetic scale field line resonances We identify electromagnetic field variations from the Van Allen Probes which have the properties of Doppler shifted kinetic scale Alfv\ enic field line resonances. These variations are observed during injections of energetic plasmas into the inner magnetosphere. These waves have scale sizes perpendicular to the magnetic field which are determined to be of the order of an ion gyro-radius (ρi) and less. Cross-spectral analysis of the electric and magnetic fields reveals phase transitions at frequencies correlated with enhancements and depressions in the ratio of the electric and magnetic fields. Modeling shows that these observations are consistent with the excitation of field-line resonances over a broad range of wave numbers perpendicular to the magnetic field (k⊥) extending to k⊥ρi >> 1. The amplitude of these waves is such that E/Bo ≳ Ωi/k⊥ (E, Bo, and Ωi are the wave amplitude, background field strength, and ion gyro-frequency, respectively) leading to ion demagnetization and acceleration for multiple transitions through the wave potential. Chaston, Christopher; Bonnell, J; Wygant, John; Mozer, Forrest; Bale, Stuart; Kersten, Kris; Breneman, Aaron; Kletzing, Craig; Kurth, William; Hospodarsky, George; Smith, Charles; MacDonald, Elizabeth; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058507 |
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One year of on-orbit performance of the Colorado Student Space Weather Experiment (CSSWE) The Colorado Student Space Weather Experiment is a 3-unit (10cm \texttimes 10cm \texttimes 30cm) CubeSat funded by the National Science Foundation and constructed at the University of Colorado (CU). The CSSWE science instrument, the Relativistic Electron and Proton Telescope integrated little experiment (REPTile), provides directional differential flux measurements of 0.5 to >3.3 MeV electrons and 9 to 40 MeV protons. Though a collaboration of 60+ multidisciplinary graduate and undergraduate students working with CU professors and engineers at the Laboratory for Atmospheric and Space Physics (LASP), CSSWE was designed, built, tested, and delivered in 3 years. On September 13, 2012, CSSWE was inserted to a 477 \texttimes 780 km, 65\textdegree orbit as a secondary payload on an Atlas V through the NASA Educational Launch of Nanosatellites (ELaNa) program. The first successful contact with CSSWE was made within a few hours of launch. CSSWE then completed a 20 day system commissioning phase which validated the performance of the communications, power, and attitude control systems. This was immediately followed by an accelerated 24 hour REPTile commissioning period in time for a geomagnetic storm. The high quality, low noise science data return from REPTile is complementary to the NASA Van Allen Probes mission, which launched two weeks prior to CSSWE. On September 13, 2013, CSSWE completed one year of on-orbit operations. In this talk we will discuss the issues encountered with designing and operating a cubesat in orbit. Data from the mission will be presented and discussed in the larger context of ionospheric and magnetospheric physics. Palo, Scott; Gerhardt, David; Li, Xinlin; Blum, Lauren; Schiller, Quintin; Kohnert, Rick; Published by: Published on: 01/2014 YEAR: 2014 DOI: 10.1109/USNC-URSI-NRSM.2014.6928087 artificial satellites; atmospheric measuring apparatus; Ionosphere; Magnetic Storms; Magnetosphere; Van Allen Probes |
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One year of on-orbit performance of the Colorado Student Space Weather Experiment (CSSWE) The Colorado Student Space Weather Experiment is a 3-unit (10cm \texttimes 10cm \texttimes 30cm) CubeSat funded by the National Science Foundation and constructed at the University of Colorado (CU). The CSSWE science instrument, the Relativistic Electron and Proton Telescope integrated little experiment (REPTile), provides directional differential flux measurements of 0.5 to >3.3 MeV electrons and 9 to 40 MeV protons. Though a collaboration of 60+ multidisciplinary graduate and undergraduate students working with CU professors and engineers at the Laboratory for Atmospheric and Space Physics (LASP), CSSWE was designed, built, tested, and delivered in 3 years. On September 13, 2012, CSSWE was inserted to a 477 \texttimes 780 km, 65\textdegree orbit as a secondary payload on an Atlas V through the NASA Educational Launch of Nanosatellites (ELaNa) program. The first successful contact with CSSWE was made within a few hours of launch. CSSWE then completed a 20 day system commissioning phase which validated the performance of the communications, power, and attitude control systems. This was immediately followed by an accelerated 24 hour REPTile commissioning period in time for a geomagnetic storm. The high quality, low noise science data return from REPTile is complementary to the NASA Van Allen Probes mission, which launched two weeks prior to CSSWE. On September 13, 2013, CSSWE completed one year of on-orbit operations. In this talk we will discuss the issues encountered with designing and operating a cubesat in orbit. Data from the mission will be presented and discussed in the larger context of ionospheric and magnetospheric physics. Palo, Scott; Gerhardt, David; Li, Xinlin; Blum, Lauren; Schiller, Quintin; Kohnert, Rick; Published by: Published on: 01/2014 YEAR: 2014 DOI: 10.1109/USNC-URSI-NRSM.2014.6928087 artificial satellites; atmospheric measuring apparatus; Ionosphere; Magnetic Storms; Magnetosphere; Van Allen Probes |
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One year of on-orbit performance of the Colorado Student Space Weather Experiment (CSSWE) The Colorado Student Space Weather Experiment is a 3-unit (10cm \texttimes 10cm \texttimes 30cm) CubeSat funded by the National Science Foundation and constructed at the University of Colorado (CU). The CSSWE science instrument, the Relativistic Electron and Proton Telescope integrated little experiment (REPTile), provides directional differential flux measurements of 0.5 to >3.3 MeV electrons and 9 to 40 MeV protons. Though a collaboration of 60+ multidisciplinary graduate and undergraduate students working with CU professors and engineers at the Laboratory for Atmospheric and Space Physics (LASP), CSSWE was designed, built, tested, and delivered in 3 years. On September 13, 2012, CSSWE was inserted to a 477 \texttimes 780 km, 65\textdegree orbit as a secondary payload on an Atlas V through the NASA Educational Launch of Nanosatellites (ELaNa) program. The first successful contact with CSSWE was made within a few hours of launch. CSSWE then completed a 20 day system commissioning phase which validated the performance of the communications, power, and attitude control systems. This was immediately followed by an accelerated 24 hour REPTile commissioning period in time for a geomagnetic storm. The high quality, low noise science data return from REPTile is complementary to the NASA Van Allen Probes mission, which launched two weeks prior to CSSWE. On September 13, 2013, CSSWE completed one year of on-orbit operations. In this talk we will discuss the issues encountered with designing and operating a cubesat in orbit. Data from the mission will be presented and discussed in the larger context of ionospheric and magnetospheric physics. Palo, Scott; Gerhardt, David; Li, Xinlin; Blum, Lauren; Schiller, Quintin; Kohnert, Rick; Published by: Published on: 01/2014 YEAR: 2014 DOI: 10.1109/USNC-URSI-NRSM.2014.6928087 artificial satellites; atmospheric measuring apparatus; Ionosphere; Magnetic Storms; Magnetosphere; Van Allen Probes |
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On 17 March 2013, a large magnetic storm significantly depleted the multi-MeV radiation belt. We present multi-instrument observations from the Van Allen Probes spacecraft Radiation Belt Storm Probe A and Radiation Belt Storm Probe B at ~6 Re in the midnight sector magnetosphere and from ground-based ionospheric sensors during a substorm dipolarization followed by rapid reenergization of multi-MeV electrons. A 50\% increase in magnetic field magnitude occurred simultaneously with dramatic increases in 100 keV electron fluxes and a 100 times increase in VLF wave intensity. The 100 keV electrons and intense VLF waves provide a seed population and energy source for subsequent radiation belt enhancements. Highly relativistic (>2 MeV) electron fluxes increased immediately at L* ~ 4.5 and 4.5 MeV flux increased >90 times at L* = 4 over 5 h. Although plasmasphere expansion brings the enhanced radiation belt multi-MeV fluxes inside the plasmasphere several hours postsubstorm, we localize their prompt reenergization during the event to regions outside the plasmasphere. Foster, J.; Erickson, P.; Baker, D.; Claudepierre, S.; Kletzing, C.; Kurth, W.; Reeves, G.; Thaller, S.; Spence, H.; Shprits, Y; Wygant, J.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058438 |
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On 17 March 2013, a large magnetic storm significantly depleted the multi-MeV radiation belt. We present multi-instrument observations from the Van Allen Probes spacecraft Radiation Belt Storm Probe A and Radiation Belt Storm Probe B at ~6 Re in the midnight sector magnetosphere and from ground-based ionospheric sensors during a substorm dipolarization followed by rapid reenergization of multi-MeV electrons. A 50\% increase in magnetic field magnitude occurred simultaneously with dramatic increases in 100 keV electron fluxes and a 100 times increase in VLF wave intensity. The 100 keV electrons and intense VLF waves provide a seed population and energy source for subsequent radiation belt enhancements. Highly relativistic (>2 MeV) electron fluxes increased immediately at L* ~ 4.5 and 4.5 MeV flux increased >90 times at L* = 4 over 5 h. Although plasmasphere expansion brings the enhanced radiation belt multi-MeV fluxes inside the plasmasphere several hours postsubstorm, we localize their prompt reenergization during the event to regions outside the plasmasphere. Foster, J.; Erickson, P.; Baker, D.; Claudepierre, S.; Kletzing, C.; Kurth, W.; Reeves, G.; Thaller, S.; Spence, H.; Shprits, Y; Wygant, J.; Published by: Geophysical Research Letters Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013GL058438 |