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Found 3761 entries in the Bibliography.
Showing entries from 301 through 350
| 2021 |
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Abstract Stable auroral red (SAR) arcs are optical events with dominant 630.0-nm emission caused by low-energy electron heat flux into the topside ionosphere from the inner magnetosphere. SAR arcs are observed at subauroral latitudes and often occur during the recovery phase of magnetic storms and substorms. Past studies concluded that these low-energy electrons were generated in the spatial overlap region between the outer plasmasphere and ring-current ions and suggested that Coulomb collisions between plasmaspheric electrons and ring-current ions are more feasible for the SAR-arc generation mechanism rather than Landau damping by electromagnetic ion cyclotron waves or kinetic Alfvén waves. This paper studies three separate SAR-arc events with conjunctions, using all-sky imagers and inner magnetospheric satellites (Arase and RBSP) during non-storm-time substorms on 19 December 2012 (event 1), 17 January 2015 (event 2), and 4 November 2019 (event 3). We evaluated for the first time the heat flux via Coulomb collision using full-energy-range ion data obtained by the satellites. The electron heat fluxes due to Coulomb collisions reached ∼109 eV/cm2/s for events 1 and 2, indicating that Coulomb collisions could have caused the SAR arcs. RBSP-A also observed local enhancements of 7–20-mHz electromagnetic wave power above the SAR arc in event 2. The heat flux for the freshly-detached SAR arc in event 3 reached ∼108 eV/cm2/s, which is insufficient to have caused the SAR arc. In event 3, local flux enhancement of electrons (<200 eV) and various electromagnetic waves were observed, these are likely to have caused the freshly-detached SAR arc. Inaba, Yudai; Shiokawa, Kazuo; Oyama, Shin-Ichiro; Otsuka, Yuichi; Connors, Martin; Schofield, Ian; Miyoshi, Yoshizumi; Imajo, Shun; Shinbori, Atsuki; Gololobov, Artem; Kazama, Yoichi; Wang, Shiang-Yu; W. Y. Tam, Sunny; Chang, Tzu-Fang; Wang, Bo-Jhou; Asamura, Kazushi; Yokota, Shoichiro; Kasahara, Satoshi; Keika, Kunihiro; Hori, Tomoaki; Matsuoka, Ayako; Kasahara, Yoshiya; Kumamoto, Atsushi; Matsuda, Shoya; Kasaba, Yasumasa; Tsuchiya, Fuminori; Shoji, Masafumi; Kitahara, Masahiro; Nakamura, Satoko; Shinohara, Iku; Spence, Harlan; Reeves, Geoff; MacDowall, Robert; Smith, Charles; Wygant, John; Bonnell, John; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA029081 SAR arc; Arase; RBSP; ring current; Non-storm-time substorm; Plasmapause; Van Allen Probes |
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Abstract Stable auroral red (SAR) arcs are optical events with dominant 630.0-nm emission caused by low-energy electron heat flux into the topside ionosphere from the inner magnetosphere. SAR arcs are observed at subauroral latitudes and often occur during the recovery phase of magnetic storms and substorms. Past studies concluded that these low-energy electrons were generated in the spatial overlap region between the outer plasmasphere and ring-current ions and suggested that Coulomb collisions between plasmaspheric electrons and ring-current ions are more feasible for the SAR-arc generation mechanism rather than Landau damping by electromagnetic ion cyclotron waves or kinetic Alfvén waves. This paper studies three separate SAR-arc events with conjunctions, using all-sky imagers and inner magnetospheric satellites (Arase and RBSP) during non-storm-time substorms on 19 December 2012 (event 1), 17 January 2015 (event 2), and 4 November 2019 (event 3). We evaluated for the first time the heat flux via Coulomb collision using full-energy-range ion data obtained by the satellites. The electron heat fluxes due to Coulomb collisions reached ∼109 eV/cm2/s for events 1 and 2, indicating that Coulomb collisions could have caused the SAR arcs. RBSP-A also observed local enhancements of 7–20-mHz electromagnetic wave power above the SAR arc in event 2. The heat flux for the freshly-detached SAR arc in event 3 reached ∼108 eV/cm2/s, which is insufficient to have caused the SAR arc. In event 3, local flux enhancement of electrons (<200 eV) and various electromagnetic waves were observed, these are likely to have caused the freshly-detached SAR arc. Inaba, Yudai; Shiokawa, Kazuo; Oyama, Shin-Ichiro; Otsuka, Yuichi; Connors, Martin; Schofield, Ian; Miyoshi, Yoshizumi; Imajo, Shun; Shinbori, Atsuki; Gololobov, Artem; Kazama, Yoichi; Wang, Shiang-Yu; W. Y. Tam, Sunny; Chang, Tzu-Fang; Wang, Bo-Jhou; Asamura, Kazushi; Yokota, Shoichiro; Kasahara, Satoshi; Keika, Kunihiro; Hori, Tomoaki; Matsuoka, Ayako; Kasahara, Yoshiya; Kumamoto, Atsushi; Matsuda, Shoya; Kasaba, Yasumasa; Tsuchiya, Fuminori; Shoji, Masafumi; Kitahara, Masahiro; Nakamura, Satoko; Shinohara, Iku; Spence, Harlan; Reeves, Geoff; MacDowall, Robert; Smith, Charles; Wygant, John; Bonnell, John; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA029081 SAR arc; Arase; RBSP; ring current; Non-storm-time substorm; Plasmapause; Van Allen Probes |
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Abstract Stable auroral red (SAR) arcs are optical events with dominant 630.0-nm emission caused by low-energy electron heat flux into the topside ionosphere from the inner magnetosphere. SAR arcs are observed at subauroral latitudes and often occur during the recovery phase of magnetic storms and substorms. Past studies concluded that these low-energy electrons were generated in the spatial overlap region between the outer plasmasphere and ring-current ions and suggested that Coulomb collisions between plasmaspheric electrons and ring-current ions are more feasible for the SAR-arc generation mechanism rather than Landau damping by electromagnetic ion cyclotron waves or kinetic Alfvén waves. This paper studies three separate SAR-arc events with conjunctions, using all-sky imagers and inner magnetospheric satellites (Arase and RBSP) during non-storm-time substorms on 19 December 2012 (event 1), 17 January 2015 (event 2), and 4 November 2019 (event 3). We evaluated for the first time the heat flux via Coulomb collision using full-energy-range ion data obtained by the satellites. The electron heat fluxes due to Coulomb collisions reached ∼109 eV/cm2/s for events 1 and 2, indicating that Coulomb collisions could have caused the SAR arcs. RBSP-A also observed local enhancements of 7–20-mHz electromagnetic wave power above the SAR arc in event 2. The heat flux for the freshly-detached SAR arc in event 3 reached ∼108 eV/cm2/s, which is insufficient to have caused the SAR arc. In event 3, local flux enhancement of electrons (<200 eV) and various electromagnetic waves were observed, these are likely to have caused the freshly-detached SAR arc. Inaba, Yudai; Shiokawa, Kazuo; Oyama, Shin-Ichiro; Otsuka, Yuichi; Connors, Martin; Schofield, Ian; Miyoshi, Yoshizumi; Imajo, Shun; Shinbori, Atsuki; Gololobov, Artem; Kazama, Yoichi; Wang, Shiang-Yu; W. Y. Tam, Sunny; Chang, Tzu-Fang; Wang, Bo-Jhou; Asamura, Kazushi; Yokota, Shoichiro; Kasahara, Satoshi; Keika, Kunihiro; Hori, Tomoaki; Matsuoka, Ayako; Kasahara, Yoshiya; Kumamoto, Atsushi; Matsuda, Shoya; Kasaba, Yasumasa; Tsuchiya, Fuminori; Shoji, Masafumi; Kitahara, Masahiro; Nakamura, Satoko; Shinohara, Iku; Spence, Harlan; Reeves, Geoff; MacDowall, Robert; Smith, Charles; Wygant, John; Bonnell, John; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA029081 SAR arc; Arase; RBSP; ring current; Non-storm-time substorm; Plasmapause; Van Allen Probes |
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Abstract Stable auroral red (SAR) arcs are optical events with dominant 630.0-nm emission caused by low-energy electron heat flux into the topside ionosphere from the inner magnetosphere. SAR arcs are observed at subauroral latitudes and often occur during the recovery phase of magnetic storms and substorms. Past studies concluded that these low-energy electrons were generated in the spatial overlap region between the outer plasmasphere and ring-current ions and suggested that Coulomb collisions between plasmaspheric electrons and ring-current ions are more feasible for the SAR-arc generation mechanism rather than Landau damping by electromagnetic ion cyclotron waves or kinetic Alfvén waves. This paper studies three separate SAR-arc events with conjunctions, using all-sky imagers and inner magnetospheric satellites (Arase and RBSP) during non-storm-time substorms on 19 December 2012 (event 1), 17 January 2015 (event 2), and 4 November 2019 (event 3). We evaluated for the first time the heat flux via Coulomb collision using full-energy-range ion data obtained by the satellites. The electron heat fluxes due to Coulomb collisions reached ∼109 eV/cm2/s for events 1 and 2, indicating that Coulomb collisions could have caused the SAR arcs. RBSP-A also observed local enhancements of 7–20-mHz electromagnetic wave power above the SAR arc in event 2. The heat flux for the freshly-detached SAR arc in event 3 reached ∼108 eV/cm2/s, which is insufficient to have caused the SAR arc. In event 3, local flux enhancement of electrons (<200 eV) and various electromagnetic waves were observed, these are likely to have caused the freshly-detached SAR arc. Inaba, Yudai; Shiokawa, Kazuo; Oyama, Shin-Ichiro; Otsuka, Yuichi; Connors, Martin; Schofield, Ian; Miyoshi, Yoshizumi; Imajo, Shun; Shinbori, Atsuki; Gololobov, Artem; Kazama, Yoichi; Wang, Shiang-Yu; W. Y. Tam, Sunny; Chang, Tzu-Fang; Wang, Bo-Jhou; Asamura, Kazushi; Yokota, Shoichiro; Kasahara, Satoshi; Keika, Kunihiro; Hori, Tomoaki; Matsuoka, Ayako; Kasahara, Yoshiya; Kumamoto, Atsushi; Matsuda, Shoya; Kasaba, Yasumasa; Tsuchiya, Fuminori; Shoji, Masafumi; Kitahara, Masahiro; Nakamura, Satoko; Shinohara, Iku; Spence, Harlan; Reeves, Geoff; MacDowall, Robert; Smith, Charles; Wygant, John; Bonnell, John; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA029081 SAR arc; Arase; RBSP; ring current; Non-storm-time substorm; Plasmapause; Van Allen Probes |
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Abstract Stable auroral red (SAR) arcs are optical events with dominant 630.0-nm emission caused by low-energy electron heat flux into the topside ionosphere from the inner magnetosphere. SAR arcs are observed at subauroral latitudes and often occur during the recovery phase of magnetic storms and substorms. Past studies concluded that these low-energy electrons were generated in the spatial overlap region between the outer plasmasphere and ring-current ions and suggested that Coulomb collisions between plasmaspheric electrons and ring-current ions are more feasible for the SAR-arc generation mechanism rather than Landau damping by electromagnetic ion cyclotron waves or kinetic Alfvén waves. This paper studies three separate SAR-arc events with conjunctions, using all-sky imagers and inner magnetospheric satellites (Arase and RBSP) during non-storm-time substorms on 19 December 2012 (event 1), 17 January 2015 (event 2), and 4 November 2019 (event 3). We evaluated for the first time the heat flux via Coulomb collision using full-energy-range ion data obtained by the satellites. The electron heat fluxes due to Coulomb collisions reached ∼109 eV/cm2/s for events 1 and 2, indicating that Coulomb collisions could have caused the SAR arcs. RBSP-A also observed local enhancements of 7–20-mHz electromagnetic wave power above the SAR arc in event 2. The heat flux for the freshly-detached SAR arc in event 3 reached ∼108 eV/cm2/s, which is insufficient to have caused the SAR arc. In event 3, local flux enhancement of electrons (<200 eV) and various electromagnetic waves were observed, these are likely to have caused the freshly-detached SAR arc. Inaba, Yudai; Shiokawa, Kazuo; Oyama, Shin-Ichiro; Otsuka, Yuichi; Connors, Martin; Schofield, Ian; Miyoshi, Yoshizumi; Imajo, Shun; Shinbori, Atsuki; Gololobov, Artem; Kazama, Yoichi; Wang, Shiang-Yu; W. Y. Tam, Sunny; Chang, Tzu-Fang; Wang, Bo-Jhou; Asamura, Kazushi; Yokota, Shoichiro; Kasahara, Satoshi; Keika, Kunihiro; Hori, Tomoaki; Matsuoka, Ayako; Kasahara, Yoshiya; Kumamoto, Atsushi; Matsuda, Shoya; Kasaba, Yasumasa; Tsuchiya, Fuminori; Shoji, Masafumi; Kitahara, Masahiro; Nakamura, Satoko; Shinohara, Iku; Spence, Harlan; Reeves, Geoff; MacDowall, Robert; Smith, Charles; Wygant, John; Bonnell, John; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA029081 SAR arc; Arase; RBSP; ring current; Non-storm-time substorm; Plasmapause; Van Allen Probes |
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In situ Observations of Whistler-mode Chorus Waves Guided by Density Ducts Abstract In this paper, we report the proof of the existence of density ducts in the Earth’s magnetosphere by studying in situ observations of whistler-mode chorus waves using NASA’s Van Allen Probe-A data. Chorus waves, originally excited inside the density ducts with wave normal angles (WNAs) smaller than the Gendrin angle at near equator region, are efficiently confined to a limited area inside density ducts (i.e., ducted regions), and remain with small WNAs as they propagate towards high latitudes. The ducted region becomes narrower for the higher-frequency waves. Chorus waves with WNAs larger than the Gendrin angle are not guided by density ducts. Our study reveals that density ducts can effectively control the property and distribution of chorus waves, and may ultimately regulate electron dynamics in the Earth’s or other planetary radiation belts. This article is protected by copyright. All rights reserved. Chen, Rui; Gao, Xinliang; Lu, Quanming; Chen, Lunjin; Tsurutani, Bruce; Li, Wen; Ni, Binbin; Wang, Shui; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028814 Radiation belt; Chorus wave; density duct; ducted region; Van Allen Probes |
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In situ Observations of Whistler-mode Chorus Waves Guided by Density Ducts Abstract In this paper, we report the proof of the existence of density ducts in the Earth’s magnetosphere by studying in situ observations of whistler-mode chorus waves using NASA’s Van Allen Probe-A data. Chorus waves, originally excited inside the density ducts with wave normal angles (WNAs) smaller than the Gendrin angle at near equator region, are efficiently confined to a limited area inside density ducts (i.e., ducted regions), and remain with small WNAs as they propagate towards high latitudes. The ducted region becomes narrower for the higher-frequency waves. Chorus waves with WNAs larger than the Gendrin angle are not guided by density ducts. Our study reveals that density ducts can effectively control the property and distribution of chorus waves, and may ultimately regulate electron dynamics in the Earth’s or other planetary radiation belts. This article is protected by copyright. All rights reserved. Chen, Rui; Gao, Xinliang; Lu, Quanming; Chen, Lunjin; Tsurutani, Bruce; Li, Wen; Ni, Binbin; Wang, Shui; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028814 Radiation belt; Chorus wave; density duct; ducted region; Van Allen Probes |
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In situ Observations of Whistler-mode Chorus Waves Guided by Density Ducts Abstract In this paper, we report the proof of the existence of density ducts in the Earth’s magnetosphere by studying in situ observations of whistler-mode chorus waves using NASA’s Van Allen Probe-A data. Chorus waves, originally excited inside the density ducts with wave normal angles (WNAs) smaller than the Gendrin angle at near equator region, are efficiently confined to a limited area inside density ducts (i.e., ducted regions), and remain with small WNAs as they propagate towards high latitudes. The ducted region becomes narrower for the higher-frequency waves. Chorus waves with WNAs larger than the Gendrin angle are not guided by density ducts. Our study reveals that density ducts can effectively control the property and distribution of chorus waves, and may ultimately regulate electron dynamics in the Earth’s or other planetary radiation belts. This article is protected by copyright. All rights reserved. Chen, Rui; Gao, Xinliang; Lu, Quanming; Chen, Lunjin; Tsurutani, Bruce; Li, Wen; Ni, Binbin; Wang, Shui; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028814 Radiation belt; Chorus wave; density duct; ducted region; Van Allen Probes |
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Abstract We have conducted a statistical study of toroidal mode standing Alfvén waves detected by the Van Allen Probes spacecraft in the dayside inner magnetosphere, with an emphasis on the nodal structure of the fundamental through fifth harmonics. We developed a technique to accurately assign harmonic mode numbers to peaks in the power spectra of the electric (Eν) and magnetic (Bϕ) field components of toroidal waves and then determine the spectral intensities of Eν and Bϕ and the coherence and cross-phase between these field components for each harmonic. The magnetic latitude (MLAT) dependence of these quantities was statistically examined to determine the location of the nodes. In addition to the equatorial nodes located close to the equator (MLAT = 0), we identified several nodes away from the equator within the MLAT range from − 20° to + 20°. We found that the Eν-Bϕ cross-phase is very close to ±90° except near the nodes, indicating that the fixed-end approximation is appropriate in modeling dayside toroidal waves. Noting that the node latitudes depend on the distribution of the mass density (ρ) along the background magnetic field, we inferred the distribution from the nodes observed at L = 4–6. If we adopt a model field line mass density (ρ) distribution of the form ρ ∝ (1/r)α, where r is geocentric distance to the field line and α is a free parameter, the statistically determined node latitudes indicate that α ∼ 1.5 is appropriate for both the plasmasphere and the plasmatrough. Takahashi, Kazue; Denton, Richard; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028981 Toroidal Alfven waves; inner magnetosphere; Nodal structure; Field line mass density distribution; Van Allen Probes |
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Abstract The impact of radial diffusion in storm time radiation belt dynamics is well-debated. In this study we quantify the changes and variability in radial diffusion coefficients during geomagnetic storms. A statistical analysis of Van Allen Probes data (2012 − 2019) is conducted to obtain measurements of the magnetic and electric power spectral densities for Ultra Low Frequency (ULF) waves, and corresponding radial diffusion coefficients. The results show global wave power enhancements occur during the storm main phase, and continue into the recovery phase. Local time asymmetries show sources of wave power are both external solar wind driving and internal sources from coupling with ring current ions and substorms. Wave power enhancements are also observed at low L values (L < 4). The accessibility of wave power to low L is attributed to a depression of the Alfvén continuum. The increased wave power drives enhancements in both the magnetic and electric field diffusion coefficients by more than an order of magnitude. Significant variability in diffusion coefficients is observed, with values ranging over several orders of magnitude. A comparison to the Kp parameterised empirical model of Ozeke et al. (2014) is conducted and indicates important differences during storm times. Although the electric field diffusion coefficient is relatively well described by the empirical model, the magnetic field diffusion coefficient is approximately ∼ 10 times larger than predicted. We discuss how differences could be attributed to dataset limitations and assumptions. Alternative storm-time radial diffusion coefficients are provided as a function of L* and storm phase. Sandhu, J.; Rae, I.; Wygant, J.; Breneman, A.; Tian, S.; Watt, C.; Horne, R.; Ozeke, L.; Georgiou, M.; Walach, M.-T.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA029024 ULF waves; radial diffusion; outer radiation belt; Van Allen Probes; Geomagnetic storms |
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Abstract The impact of radial diffusion in storm time radiation belt dynamics is well-debated. In this study we quantify the changes and variability in radial diffusion coefficients during geomagnetic storms. A statistical analysis of Van Allen Probes data (2012 − 2019) is conducted to obtain measurements of the magnetic and electric power spectral densities for Ultra Low Frequency (ULF) waves, and corresponding radial diffusion coefficients. The results show global wave power enhancements occur during the storm main phase, and continue into the recovery phase. Local time asymmetries show sources of wave power are both external solar wind driving and internal sources from coupling with ring current ions and substorms. Wave power enhancements are also observed at low L values (L < 4). The accessibility of wave power to low L is attributed to a depression of the Alfvén continuum. The increased wave power drives enhancements in both the magnetic and electric field diffusion coefficients by more than an order of magnitude. Significant variability in diffusion coefficients is observed, with values ranging over several orders of magnitude. A comparison to the Kp parameterised empirical model of Ozeke et al. (2014) is conducted and indicates important differences during storm times. Although the electric field diffusion coefficient is relatively well described by the empirical model, the magnetic field diffusion coefficient is approximately ∼ 10 times larger than predicted. We discuss how differences could be attributed to dataset limitations and assumptions. Alternative storm-time radial diffusion coefficients are provided as a function of L* and storm phase. Sandhu, J.; Rae, I.; Wygant, J.; Breneman, A.; Tian, S.; Watt, C.; Horne, R.; Ozeke, L.; Georgiou, M.; Walach, M.-T.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA029024 ULF waves; radial diffusion; outer radiation belt; Van Allen Probes; Geomagnetic storms |
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Abstract The impact of radial diffusion in storm time radiation belt dynamics is well-debated. In this study we quantify the changes and variability in radial diffusion coefficients during geomagnetic storms. A statistical analysis of Van Allen Probes data (2012 − 2019) is conducted to obtain measurements of the magnetic and electric power spectral densities for Ultra Low Frequency (ULF) waves, and corresponding radial diffusion coefficients. The results show global wave power enhancements occur during the storm main phase, and continue into the recovery phase. Local time asymmetries show sources of wave power are both external solar wind driving and internal sources from coupling with ring current ions and substorms. Wave power enhancements are also observed at low L values (L < 4). The accessibility of wave power to low L is attributed to a depression of the Alfvén continuum. The increased wave power drives enhancements in both the magnetic and electric field diffusion coefficients by more than an order of magnitude. Significant variability in diffusion coefficients is observed, with values ranging over several orders of magnitude. A comparison to the Kp parameterised empirical model of Ozeke et al. (2014) is conducted and indicates important differences during storm times. Although the electric field diffusion coefficient is relatively well described by the empirical model, the magnetic field diffusion coefficient is approximately ∼ 10 times larger than predicted. We discuss how differences could be attributed to dataset limitations and assumptions. Alternative storm-time radial diffusion coefficients are provided as a function of L* and storm phase. Sandhu, J.; Rae, I.; Wygant, J.; Breneman, A.; Tian, S.; Watt, C.; Horne, R.; Ozeke, L.; Georgiou, M.; Walach, M.-T.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA029024 ULF waves; radial diffusion; outer radiation belt; Van Allen Probes; Geomagnetic storms |
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Abstract The impact of radial diffusion in storm time radiation belt dynamics is well-debated. In this study we quantify the changes and variability in radial diffusion coefficients during geomagnetic storms. A statistical analysis of Van Allen Probes data (2012 − 2019) is conducted to obtain measurements of the magnetic and electric power spectral densities for Ultra Low Frequency (ULF) waves, and corresponding radial diffusion coefficients. The results show global wave power enhancements occur during the storm main phase, and continue into the recovery phase. Local time asymmetries show sources of wave power are both external solar wind driving and internal sources from coupling with ring current ions and substorms. Wave power enhancements are also observed at low L values (L < 4). The accessibility of wave power to low L is attributed to a depression of the Alfvén continuum. The increased wave power drives enhancements in both the magnetic and electric field diffusion coefficients by more than an order of magnitude. Significant variability in diffusion coefficients is observed, with values ranging over several orders of magnitude. A comparison to the Kp parameterised empirical model of Ozeke et al. (2014) is conducted and indicates important differences during storm times. Although the electric field diffusion coefficient is relatively well described by the empirical model, the magnetic field diffusion coefficient is approximately ∼ 10 times larger than predicted. We discuss how differences could be attributed to dataset limitations and assumptions. Alternative storm-time radial diffusion coefficients are provided as a function of L* and storm phase. Sandhu, J.; Rae, I.; Wygant, J.; Breneman, A.; Tian, S.; Watt, C.; Horne, R.; Ozeke, L.; Georgiou, M.; Walach, M.-T.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA029024 ULF waves; radial diffusion; outer radiation belt; Van Allen Probes; Geomagnetic storms |
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Abstract The impact of radial diffusion in storm time radiation belt dynamics is well-debated. In this study we quantify the changes and variability in radial diffusion coefficients during geomagnetic storms. A statistical analysis of Van Allen Probes data (2012 − 2019) is conducted to obtain measurements of the magnetic and electric power spectral densities for Ultra Low Frequency (ULF) waves, and corresponding radial diffusion coefficients. The results show global wave power enhancements occur during the storm main phase, and continue into the recovery phase. Local time asymmetries show sources of wave power are both external solar wind driving and internal sources from coupling with ring current ions and substorms. Wave power enhancements are also observed at low L values (L < 4). The accessibility of wave power to low L is attributed to a depression of the Alfvén continuum. The increased wave power drives enhancements in both the magnetic and electric field diffusion coefficients by more than an order of magnitude. Significant variability in diffusion coefficients is observed, with values ranging over several orders of magnitude. A comparison to the Kp parameterised empirical model of Ozeke et al. (2014) is conducted and indicates important differences during storm times. Although the electric field diffusion coefficient is relatively well described by the empirical model, the magnetic field diffusion coefficient is approximately ∼ 10 times larger than predicted. We discuss how differences could be attributed to dataset limitations and assumptions. Alternative storm-time radial diffusion coefficients are provided as a function of L* and storm phase. Sandhu, J.; Rae, I.; Wygant, J.; Breneman, A.; Tian, S.; Watt, C.; Horne, R.; Ozeke, L.; Georgiou, M.; Walach, M.-T.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA029024 ULF waves; radial diffusion; outer radiation belt; Van Allen Probes; Geomagnetic storms |
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Abstract The impact of radial diffusion in storm time radiation belt dynamics is well-debated. In this study we quantify the changes and variability in radial diffusion coefficients during geomagnetic storms. A statistical analysis of Van Allen Probes data (2012 − 2019) is conducted to obtain measurements of the magnetic and electric power spectral densities for Ultra Low Frequency (ULF) waves, and corresponding radial diffusion coefficients. The results show global wave power enhancements occur during the storm main phase, and continue into the recovery phase. Local time asymmetries show sources of wave power are both external solar wind driving and internal sources from coupling with ring current ions and substorms. Wave power enhancements are also observed at low L values (L < 4). The accessibility of wave power to low L is attributed to a depression of the Alfvén continuum. The increased wave power drives enhancements in both the magnetic and electric field diffusion coefficients by more than an order of magnitude. Significant variability in diffusion coefficients is observed, with values ranging over several orders of magnitude. A comparison to the Kp parameterised empirical model of Ozeke et al. (2014) is conducted and indicates important differences during storm times. Although the electric field diffusion coefficient is relatively well described by the empirical model, the magnetic field diffusion coefficient is approximately ∼ 10 times larger than predicted. We discuss how differences could be attributed to dataset limitations and assumptions. Alternative storm-time radial diffusion coefficients are provided as a function of L* and storm phase. Sandhu, J.; Rae, I.; Wygant, J.; Breneman, A.; Tian, S.; Watt, C.; Horne, R.; Ozeke, L.; Georgiou, M.; Walach, M.-T.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA029024 ULF waves; radial diffusion; outer radiation belt; Van Allen Probes; Geomagnetic storms |
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Abstract The impact of radial diffusion in storm time radiation belt dynamics is well-debated. In this study we quantify the changes and variability in radial diffusion coefficients during geomagnetic storms. A statistical analysis of Van Allen Probes data (2012 − 2019) is conducted to obtain measurements of the magnetic and electric power spectral densities for Ultra Low Frequency (ULF) waves, and corresponding radial diffusion coefficients. The results show global wave power enhancements occur during the storm main phase, and continue into the recovery phase. Local time asymmetries show sources of wave power are both external solar wind driving and internal sources from coupling with ring current ions and substorms. Wave power enhancements are also observed at low L values (L < 4). The accessibility of wave power to low L is attributed to a depression of the Alfvén continuum. The increased wave power drives enhancements in both the magnetic and electric field diffusion coefficients by more than an order of magnitude. Significant variability in diffusion coefficients is observed, with values ranging over several orders of magnitude. A comparison to the Kp parameterised empirical model of Ozeke et al. (2014) is conducted and indicates important differences during storm times. Although the electric field diffusion coefficient is relatively well described by the empirical model, the magnetic field diffusion coefficient is approximately ∼ 10 times larger than predicted. We discuss how differences could be attributed to dataset limitations and assumptions. Alternative storm-time radial diffusion coefficients are provided as a function of L* and storm phase. Sandhu, J.; Rae, I.; Wygant, J.; Breneman, A.; Tian, S.; Watt, C.; Horne, R.; Ozeke, L.; Georgiou, M.; Walach, M.-T.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA029024 ULF waves; radial diffusion; outer radiation belt; Van Allen Probes; Geomagnetic storms |
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Abstract We present, for the first time, a plasmaspheric hiss event observed by the Van Allen probes in response to two successive interplanetary shocks occurring within an interval of ∼2 hours on December 19, 2015. The first shock arrived at 16:16 UT and caused disappearance of hiss for ∼30 minutes. Combined effect of plasmapause crossing, significant Landau damping by suprathermal electrons and their gradual removal by magnetospheric compression led to the disappearance of hiss. Calculation of electron phase space density and linear wave growth rates showed that the shock did not change the growth rate of whistler waves within the core frequency range of plasmaspheric hiss (0.1 - 0.5 kHz) during this interval making conditions unfavorable for the generation of hiss. The recovery began at ∼16:45 UT which is attributed to an enhancement in local plasma instability initiated by the first shock-induced substorm and additional possible contribution from chorus waves. This time, the wave growth rate peaked within the core frequency range ( ∼350 Hz). The second shock arrived at 18:02 UT and generated patchy hiss persisting up to ∼19:00 UT. It is shown that an enhanced growth rate and additional contribution from shock-induced poloidal Pc5 mode (periodicity ∼240 sec) ULF waves resulted in the excitation of hiss waves during this period. The hiss wave amplitudes were found to be additionally modulated by background plasma density and fluctuating plasmapause location. The investigation highlights the important roles of interplanetary shocks, substorms, ULF waves and background plasma density in the variability of plasmaspheric hiss. Chakraborty, S.; Chakrabarty, D.; Reeves, G.; Baker, D.; Claudepierre, S.; Breneman, A.; Hartley, D.; Larsen, B.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028873 Plasmaspheric Hiss; Van Allen Probe; Interplanetary shocks; substorms; Whistlers; ULF waves; Van Allen Probes |
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Abstract We present, for the first time, a plasmaspheric hiss event observed by the Van Allen probes in response to two successive interplanetary shocks occurring within an interval of ∼2 hours on December 19, 2015. The first shock arrived at 16:16 UT and caused disappearance of hiss for ∼30 minutes. Combined effect of plasmapause crossing, significant Landau damping by suprathermal electrons and their gradual removal by magnetospheric compression led to the disappearance of hiss. Calculation of electron phase space density and linear wave growth rates showed that the shock did not change the growth rate of whistler waves within the core frequency range of plasmaspheric hiss (0.1 - 0.5 kHz) during this interval making conditions unfavorable for the generation of hiss. The recovery began at ∼16:45 UT which is attributed to an enhancement in local plasma instability initiated by the first shock-induced substorm and additional possible contribution from chorus waves. This time, the wave growth rate peaked within the core frequency range ( ∼350 Hz). The second shock arrived at 18:02 UT and generated patchy hiss persisting up to ∼19:00 UT. It is shown that an enhanced growth rate and additional contribution from shock-induced poloidal Pc5 mode (periodicity ∼240 sec) ULF waves resulted in the excitation of hiss waves during this period. The hiss wave amplitudes were found to be additionally modulated by background plasma density and fluctuating plasmapause location. The investigation highlights the important roles of interplanetary shocks, substorms, ULF waves and background plasma density in the variability of plasmaspheric hiss. Chakraborty, S.; Chakrabarty, D.; Reeves, G.; Baker, D.; Claudepierre, S.; Breneman, A.; Hartley, D.; Larsen, B.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028873 Plasmaspheric Hiss; Van Allen Probe; Interplanetary shocks; substorms; Whistlers; ULF waves; Van Allen Probes |
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Abstract We present, for the first time, a plasmaspheric hiss event observed by the Van Allen probes in response to two successive interplanetary shocks occurring within an interval of ∼2 hours on December 19, 2015. The first shock arrived at 16:16 UT and caused disappearance of hiss for ∼30 minutes. Combined effect of plasmapause crossing, significant Landau damping by suprathermal electrons and their gradual removal by magnetospheric compression led to the disappearance of hiss. Calculation of electron phase space density and linear wave growth rates showed that the shock did not change the growth rate of whistler waves within the core frequency range of plasmaspheric hiss (0.1 - 0.5 kHz) during this interval making conditions unfavorable for the generation of hiss. The recovery began at ∼16:45 UT which is attributed to an enhancement in local plasma instability initiated by the first shock-induced substorm and additional possible contribution from chorus waves. This time, the wave growth rate peaked within the core frequency range ( ∼350 Hz). The second shock arrived at 18:02 UT and generated patchy hiss persisting up to ∼19:00 UT. It is shown that an enhanced growth rate and additional contribution from shock-induced poloidal Pc5 mode (periodicity ∼240 sec) ULF waves resulted in the excitation of hiss waves during this period. The hiss wave amplitudes were found to be additionally modulated by background plasma density and fluctuating plasmapause location. The investigation highlights the important roles of interplanetary shocks, substorms, ULF waves and background plasma density in the variability of plasmaspheric hiss. Chakraborty, S.; Chakrabarty, D.; Reeves, G.; Baker, D.; Claudepierre, S.; Breneman, A.; Hartley, D.; Larsen, B.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028873 Plasmaspheric Hiss; Van Allen Probe; Interplanetary shocks; substorms; Whistlers; ULF waves; Van Allen Probes |
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Abstract We present, for the first time, a plasmaspheric hiss event observed by the Van Allen probes in response to two successive interplanetary shocks occurring within an interval of ∼2 hours on December 19, 2015. The first shock arrived at 16:16 UT and caused disappearance of hiss for ∼30 minutes. Combined effect of plasmapause crossing, significant Landau damping by suprathermal electrons and their gradual removal by magnetospheric compression led to the disappearance of hiss. Calculation of electron phase space density and linear wave growth rates showed that the shock did not change the growth rate of whistler waves within the core frequency range of plasmaspheric hiss (0.1 - 0.5 kHz) during this interval making conditions unfavorable for the generation of hiss. The recovery began at ∼16:45 UT which is attributed to an enhancement in local plasma instability initiated by the first shock-induced substorm and additional possible contribution from chorus waves. This time, the wave growth rate peaked within the core frequency range ( ∼350 Hz). The second shock arrived at 18:02 UT and generated patchy hiss persisting up to ∼19:00 UT. It is shown that an enhanced growth rate and additional contribution from shock-induced poloidal Pc5 mode (periodicity ∼240 sec) ULF waves resulted in the excitation of hiss waves during this period. The hiss wave amplitudes were found to be additionally modulated by background plasma density and fluctuating plasmapause location. The investigation highlights the important roles of interplanetary shocks, substorms, ULF waves and background plasma density in the variability of plasmaspheric hiss. Chakraborty, S.; Chakrabarty, D.; Reeves, G.; Baker, D.; Claudepierre, S.; Breneman, A.; Hartley, D.; Larsen, B.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028873 Plasmaspheric Hiss; Van Allen Probe; Interplanetary shocks; substorms; Whistlers; ULF waves; Van Allen Probes |
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Abstract We present, for the first time, a plasmaspheric hiss event observed by the Van Allen probes in response to two successive interplanetary shocks occurring within an interval of ∼2 hours on December 19, 2015. The first shock arrived at 16:16 UT and caused disappearance of hiss for ∼30 minutes. Combined effect of plasmapause crossing, significant Landau damping by suprathermal electrons and their gradual removal by magnetospheric compression led to the disappearance of hiss. Calculation of electron phase space density and linear wave growth rates showed that the shock did not change the growth rate of whistler waves within the core frequency range of plasmaspheric hiss (0.1 - 0.5 kHz) during this interval making conditions unfavorable for the generation of hiss. The recovery began at ∼16:45 UT which is attributed to an enhancement in local plasma instability initiated by the first shock-induced substorm and additional possible contribution from chorus waves. This time, the wave growth rate peaked within the core frequency range ( ∼350 Hz). The second shock arrived at 18:02 UT and generated patchy hiss persisting up to ∼19:00 UT. It is shown that an enhanced growth rate and additional contribution from shock-induced poloidal Pc5 mode (periodicity ∼240 sec) ULF waves resulted in the excitation of hiss waves during this period. The hiss wave amplitudes were found to be additionally modulated by background plasma density and fluctuating plasmapause location. The investigation highlights the important roles of interplanetary shocks, substorms, ULF waves and background plasma density in the variability of plasmaspheric hiss. Chakraborty, S.; Chakrabarty, D.; Reeves, G.; Baker, D.; Claudepierre, S.; Breneman, A.; Hartley, D.; Larsen, B.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028873 Plasmaspheric Hiss; Van Allen Probe; Interplanetary shocks; substorms; Whistlers; ULF waves; Van Allen Probes |
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Abstract We present, for the first time, a plasmaspheric hiss event observed by the Van Allen probes in response to two successive interplanetary shocks occurring within an interval of ∼2 hours on December 19, 2015. The first shock arrived at 16:16 UT and caused disappearance of hiss for ∼30 minutes. Combined effect of plasmapause crossing, significant Landau damping by suprathermal electrons and their gradual removal by magnetospheric compression led to the disappearance of hiss. Calculation of electron phase space density and linear wave growth rates showed that the shock did not change the growth rate of whistler waves within the core frequency range of plasmaspheric hiss (0.1 - 0.5 kHz) during this interval making conditions unfavorable for the generation of hiss. The recovery began at ∼16:45 UT which is attributed to an enhancement in local plasma instability initiated by the first shock-induced substorm and additional possible contribution from chorus waves. This time, the wave growth rate peaked within the core frequency range ( ∼350 Hz). The second shock arrived at 18:02 UT and generated patchy hiss persisting up to ∼19:00 UT. It is shown that an enhanced growth rate and additional contribution from shock-induced poloidal Pc5 mode (periodicity ∼240 sec) ULF waves resulted in the excitation of hiss waves during this period. The hiss wave amplitudes were found to be additionally modulated by background plasma density and fluctuating plasmapause location. The investigation highlights the important roles of interplanetary shocks, substorms, ULF waves and background plasma density in the variability of plasmaspheric hiss. Chakraborty, S.; Chakrabarty, D.; Reeves, G.; Baker, D.; Claudepierre, S.; Breneman, A.; Hartley, D.; Larsen, B.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028873 Plasmaspheric Hiss; Van Allen Probe; Interplanetary shocks; substorms; Whistlers; ULF waves; Van Allen Probes |
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Abstract We present, for the first time, a plasmaspheric hiss event observed by the Van Allen probes in response to two successive interplanetary shocks occurring within an interval of ∼2 hours on December 19, 2015. The first shock arrived at 16:16 UT and caused disappearance of hiss for ∼30 minutes. Combined effect of plasmapause crossing, significant Landau damping by suprathermal electrons and their gradual removal by magnetospheric compression led to the disappearance of hiss. Calculation of electron phase space density and linear wave growth rates showed that the shock did not change the growth rate of whistler waves within the core frequency range of plasmaspheric hiss (0.1 - 0.5 kHz) during this interval making conditions unfavorable for the generation of hiss. The recovery began at ∼16:45 UT which is attributed to an enhancement in local plasma instability initiated by the first shock-induced substorm and additional possible contribution from chorus waves. This time, the wave growth rate peaked within the core frequency range ( ∼350 Hz). The second shock arrived at 18:02 UT and generated patchy hiss persisting up to ∼19:00 UT. It is shown that an enhanced growth rate and additional contribution from shock-induced poloidal Pc5 mode (periodicity ∼240 sec) ULF waves resulted in the excitation of hiss waves during this period. The hiss wave amplitudes were found to be additionally modulated by background plasma density and fluctuating plasmapause location. The investigation highlights the important roles of interplanetary shocks, substorms, ULF waves and background plasma density in the variability of plasmaspheric hiss. Chakraborty, S.; Chakrabarty, D.; Reeves, G.; Baker, D.; Claudepierre, S.; Breneman, A.; Hartley, D.; Larsen, B.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028873 Plasmaspheric Hiss; Van Allen Probe; Interplanetary shocks; substorms; Whistlers; ULF waves; Van Allen Probes |
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A Comparison of the Location of the Mid-latitude Trough and Plasmapause Boundary Abstract We have compared the location of the mid-latitude trough observed in two dimensional vertical total electron content (vTEC) maps with four plasmapause boundary models, Radiation Belt Storm Probes observations, and IMAGE EUV observations all mapped to the ionosphere pierce point using the Tsyganenko [1996] magnetic field line model. For this study we examine four events over North America: one just after the 13 October 2012 storm, one during the 20 April 2002 double storm, another during a large substorm on 26 January 2013, and one quiet event on 19 May 2001. We have found that in general, the equatorward edge of the mid-latitude trough is within several degrees in geographic latitude of the mapped model plasmapause boundary location, the plasmapause boundary identified with IMAGE EUV, and the location identified by the Radiation Belt Storm Probes spacecraft. When the mid-latitude trough is mapped to the inner magnetosphere, the observed boundary agrees with the plasmapause boundary models within 2 Earth Radii at nearly all local times in the nightside and the observed mid-latitude boundary is within the uncertainty of the observations at most local times in the nightside. Furthermore, during dynamic solar wind conditions of 20 April 2002, the mid-latitude trough observed in the vTEC maps propagates equatorward as the plasmapause boundary identified with IMAGE EUV moves earthward. Our results indicate that the mid-latitude trough observed within the vTEC maps represents an additional means of identifying the plasmapause boundary location, which could result in improved plasmapause boundary models. This article is protected by copyright. All rights reserved. Weygand, J.M.; Zhelavskaya, I.; Shprits, Y.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028213 mid-latitude trough; plasmapause boundary; vTECs; plasmapause models; Van Allen Probes |
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A Comparison of the Location of the Mid-latitude Trough and Plasmapause Boundary Abstract We have compared the location of the mid-latitude trough observed in two dimensional vertical total electron content (vTEC) maps with four plasmapause boundary models, Radiation Belt Storm Probes observations, and IMAGE EUV observations all mapped to the ionosphere pierce point using the Tsyganenko [1996] magnetic field line model. For this study we examine four events over North America: one just after the 13 October 2012 storm, one during the 20 April 2002 double storm, another during a large substorm on 26 January 2013, and one quiet event on 19 May 2001. We have found that in general, the equatorward edge of the mid-latitude trough is within several degrees in geographic latitude of the mapped model plasmapause boundary location, the plasmapause boundary identified with IMAGE EUV, and the location identified by the Radiation Belt Storm Probes spacecraft. When the mid-latitude trough is mapped to the inner magnetosphere, the observed boundary agrees with the plasmapause boundary models within 2 Earth Radii at nearly all local times in the nightside and the observed mid-latitude boundary is within the uncertainty of the observations at most local times in the nightside. Furthermore, during dynamic solar wind conditions of 20 April 2002, the mid-latitude trough observed in the vTEC maps propagates equatorward as the plasmapause boundary identified with IMAGE EUV moves earthward. Our results indicate that the mid-latitude trough observed within the vTEC maps represents an additional means of identifying the plasmapause boundary location, which could result in improved plasmapause boundary models. This article is protected by copyright. All rights reserved. Weygand, J.M.; Zhelavskaya, I.; Shprits, Y.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028213 mid-latitude trough; plasmapause boundary; vTECs; plasmapause models; Van Allen Probes |
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Formation of the mass density peak at the magnetospheric equator triggered by EMIC waves Abstract We report a simultaneous observation of two band electromagnetic ion cyclotron (EMIC) waves and toroidal Alfvén waves by the Van Allen Probe mission. Through wave frequency analyses, the mass density ρ is found to be locally peaked at the magnetic equator. Perpendicular fluxes of ions (< 100 eV) increase simultaneously with the appearances of EMIC waves, indicating a heating of these ions by EMIC waves. In addition, the measured ion distributions also support the equatorial peak formation, which accords with the result of the frequency analyses. The formation of local mass density peaks at the equator should be due to enhancements of equatorial ion concentrations, which are triggered by EMIC waves’ perpendicular heating on low energy ions. Xue, Zuxiang; Yuan, Zhigang; Yu, Xiongdong; Shiyong, Huang; Qiao, Zheng; Published by: Earth and Planetary Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.26464/epp2021008 Toroidal Alfven waves; EMIC waves; magnetoseismology; equatorial mass density peak; Van Allen Probes |
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Formation of the mass density peak at the magnetospheric equator triggered by EMIC waves Abstract We report a simultaneous observation of two band electromagnetic ion cyclotron (EMIC) waves and toroidal Alfvén waves by the Van Allen Probe mission. Through wave frequency analyses, the mass density ρ is found to be locally peaked at the magnetic equator. Perpendicular fluxes of ions (< 100 eV) increase simultaneously with the appearances of EMIC waves, indicating a heating of these ions by EMIC waves. In addition, the measured ion distributions also support the equatorial peak formation, which accords with the result of the frequency analyses. The formation of local mass density peaks at the equator should be due to enhancements of equatorial ion concentrations, which are triggered by EMIC waves’ perpendicular heating on low energy ions. Xue, Zuxiang; Yuan, Zhigang; Yu, Xiongdong; Shiyong, Huang; Qiao, Zheng; Published by: Earth and Planetary Physics Published on: 03/2021 YEAR: 2021 DOI: https://doi.org/10.26464/epp2021008 Toroidal Alfven waves; EMIC waves; magnetoseismology; equatorial mass density peak; Van Allen Probes |
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Abstract We evaluate the location, extent and energy range of electron precipitation driven by ElectroMagnetic Ion Cyclotron (EMIC) waves using coordinated multi-satellite observations from near-equatorial and Low-Earth-Orbit (LEO) missions. Electron precipitation was analyzed using the Focused Investigations of Relativistic Electron Burst Intensity, Range and Dynamics (FIREBIRD-II) CubeSats, in conjunction either with typical EMIC-driven precipitation signatures observed by Polar Orbiting Environmental Satellites (POES) or with in situ EMIC wave observations from Van Allen Probes. The multi-event analysis shows that electron precipitation occurred in a broad region near dusk (16–23 MLT), mostly confined to 3.5–7.5 L- shells. Each precipitation event occurred on localized radial scales, on average ∼0.3 L. Most importantly, FIREBIRD-II recorded electron precipitation from ∼200–300 keV to the expected ∼MeV energies for most cases, suggesting that EMIC waves can efficiently scatter a wide energy range of electrons. Capannolo, L.; Li, W.; Spence, H.; Johnson, A.; Shumko, M.; Sample, J.; Klumpar, D.; Published by: Geophysical Research Letters Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020GL091564 electron precipitation; EMIC waves; inner magnetosphere; electron losses; proton precipitation; wave-particle interactions; Van Allen Probes |
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Abstract We evaluate the location, extent and energy range of electron precipitation driven by ElectroMagnetic Ion Cyclotron (EMIC) waves using coordinated multi-satellite observations from near-equatorial and Low-Earth-Orbit (LEO) missions. Electron precipitation was analyzed using the Focused Investigations of Relativistic Electron Burst Intensity, Range and Dynamics (FIREBIRD-II) CubeSats, in conjunction either with typical EMIC-driven precipitation signatures observed by Polar Orbiting Environmental Satellites (POES) or with in situ EMIC wave observations from Van Allen Probes. The multi-event analysis shows that electron precipitation occurred in a broad region near dusk (16–23 MLT), mostly confined to 3.5–7.5 L- shells. Each precipitation event occurred on localized radial scales, on average ∼0.3 L. Most importantly, FIREBIRD-II recorded electron precipitation from ∼200–300 keV to the expected ∼MeV energies for most cases, suggesting that EMIC waves can efficiently scatter a wide energy range of electrons. Capannolo, L.; Li, W.; Spence, H.; Johnson, A.; Shumko, M.; Sample, J.; Klumpar, D.; Published by: Geophysical Research Letters Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020GL091564 electron precipitation; EMIC waves; inner magnetosphere; electron losses; proton precipitation; wave-particle interactions; Van Allen Probes |
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Abstract We evaluate the location, extent and energy range of electron precipitation driven by ElectroMagnetic Ion Cyclotron (EMIC) waves using coordinated multi-satellite observations from near-equatorial and Low-Earth-Orbit (LEO) missions. Electron precipitation was analyzed using the Focused Investigations of Relativistic Electron Burst Intensity, Range and Dynamics (FIREBIRD-II) CubeSats, in conjunction either with typical EMIC-driven precipitation signatures observed by Polar Orbiting Environmental Satellites (POES) or with in situ EMIC wave observations from Van Allen Probes. The multi-event analysis shows that electron precipitation occurred in a broad region near dusk (16–23 MLT), mostly confined to 3.5–7.5 L- shells. Each precipitation event occurred on localized radial scales, on average ∼0.3 L. Most importantly, FIREBIRD-II recorded electron precipitation from ∼200–300 keV to the expected ∼MeV energies for most cases, suggesting that EMIC waves can efficiently scatter a wide energy range of electrons. Capannolo, L.; Li, W.; Spence, H.; Johnson, A.; Shumko, M.; Sample, J.; Klumpar, D.; Published by: Geophysical Research Letters Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020GL091564 electron precipitation; EMIC waves; inner magnetosphere; electron losses; proton precipitation; wave-particle interactions; Van Allen Probes |
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Reconstruction of the Radiation Belts for Solar Cycles 17 – 24 (1933 – 2017) AbstractWe present a reconstruction of the dynamics of the radiation belts from Solar Cycles 17 – 24 which allows us to study how radiation belt activity has varied between the different solar cycles. The radiation belt simulations are produced using the Versatile Electron Radiation Belt (VERB)-3D code. The VERB-3D code simulations incorporate radial, energy, and pitch angle diffusion to reproduce the radiation belts. Our simulations use the historical measurements of Kp (available since Solar Cycle 17, i.e., 1933) to model the evolution radiation belt dynamics between L* = 1 – 6.6. A nonlinear auto regressive network with exogenous inputs (NARX) neural network was trained off GOES 15 measurements (Jan. 2011 – March 2014) and used to supply the upper boundary condition (L* = 6.6) over the course of Solar Cycles 17 – 24 (i.e., 1933 – 2017). Comparison of the model with long term observations of the Van Allen Probes and CRRES demonstrates that our model, driven by the NARX boundary, can reconstruct the general evolution of the radiation belt fluxes. Solar Cycle 24 (Jan 2008 – 2017) has been the least active of the considered solar cycles which resulted in unusually low electron fluxes. Our results show that Solar Cycle 24 should not be used as a representative solar cycle for developing long term environment models. The developed reconstruction of fluxes can be used to develop or improve empirical models of the radiation belts.This article is protected by copyright. All rights reserved. Saikin, A.; Shprits, Y; Drozdov, A; Landis, D.; Zhelavskaya, I.; Cervantes, S.; Published by: Space Weather Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020SW002524 Radiation belts; numerical modeling; Particle acceleration; Magnetosphere: inner; forecasting; Van Allen Probes |
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Reconstruction of the Radiation Belts for Solar Cycles 17 – 24 (1933 – 2017) AbstractWe present a reconstruction of the dynamics of the radiation belts from Solar Cycles 17 – 24 which allows us to study how radiation belt activity has varied between the different solar cycles. The radiation belt simulations are produced using the Versatile Electron Radiation Belt (VERB)-3D code. The VERB-3D code simulations incorporate radial, energy, and pitch angle diffusion to reproduce the radiation belts. Our simulations use the historical measurements of Kp (available since Solar Cycle 17, i.e., 1933) to model the evolution radiation belt dynamics between L* = 1 – 6.6. A nonlinear auto regressive network with exogenous inputs (NARX) neural network was trained off GOES 15 measurements (Jan. 2011 – March 2014) and used to supply the upper boundary condition (L* = 6.6) over the course of Solar Cycles 17 – 24 (i.e., 1933 – 2017). Comparison of the model with long term observations of the Van Allen Probes and CRRES demonstrates that our model, driven by the NARX boundary, can reconstruct the general evolution of the radiation belt fluxes. Solar Cycle 24 (Jan 2008 – 2017) has been the least active of the considered solar cycles which resulted in unusually low electron fluxes. Our results show that Solar Cycle 24 should not be used as a representative solar cycle for developing long term environment models. The developed reconstruction of fluxes can be used to develop or improve empirical models of the radiation belts.This article is protected by copyright. All rights reserved. Saikin, A.; Shprits, Y; Drozdov, A; Landis, D.; Zhelavskaya, I.; Cervantes, S.; Published by: Space Weather Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020SW002524 Radiation belts; numerical modeling; Particle acceleration; Magnetosphere: inner; forecasting; Van Allen Probes |
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Reconstruction of the Radiation Belts for Solar Cycles 17 – 24 (1933 – 2017) AbstractWe present a reconstruction of the dynamics of the radiation belts from Solar Cycles 17 – 24 which allows us to study how radiation belt activity has varied between the different solar cycles. The radiation belt simulations are produced using the Versatile Electron Radiation Belt (VERB)-3D code. The VERB-3D code simulations incorporate radial, energy, and pitch angle diffusion to reproduce the radiation belts. Our simulations use the historical measurements of Kp (available since Solar Cycle 17, i.e., 1933) to model the evolution radiation belt dynamics between L* = 1 – 6.6. A nonlinear auto regressive network with exogenous inputs (NARX) neural network was trained off GOES 15 measurements (Jan. 2011 – March 2014) and used to supply the upper boundary condition (L* = 6.6) over the course of Solar Cycles 17 – 24 (i.e., 1933 – 2017). Comparison of the model with long term observations of the Van Allen Probes and CRRES demonstrates that our model, driven by the NARX boundary, can reconstruct the general evolution of the radiation belt fluxes. Solar Cycle 24 (Jan 2008 – 2017) has been the least active of the considered solar cycles which resulted in unusually low electron fluxes. Our results show that Solar Cycle 24 should not be used as a representative solar cycle for developing long term environment models. The developed reconstruction of fluxes can be used to develop or improve empirical models of the radiation belts.This article is protected by copyright. All rights reserved. Saikin, A.; Shprits, Y; Drozdov, A; Landis, D.; Zhelavskaya, I.; Cervantes, S.; Published by: Space Weather Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020SW002524 Radiation belts; numerical modeling; Particle acceleration; Magnetosphere: inner; forecasting; Van Allen Probes |
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Reconstruction of the Radiation Belts for Solar Cycles 17 – 24 (1933 – 2017) AbstractWe present a reconstruction of the dynamics of the radiation belts from Solar Cycles 17 – 24 which allows us to study how radiation belt activity has varied between the different solar cycles. The radiation belt simulations are produced using the Versatile Electron Radiation Belt (VERB)-3D code. The VERB-3D code simulations incorporate radial, energy, and pitch angle diffusion to reproduce the radiation belts. Our simulations use the historical measurements of Kp (available since Solar Cycle 17, i.e., 1933) to model the evolution radiation belt dynamics between L* = 1 – 6.6. A nonlinear auto regressive network with exogenous inputs (NARX) neural network was trained off GOES 15 measurements (Jan. 2011 – March 2014) and used to supply the upper boundary condition (L* = 6.6) over the course of Solar Cycles 17 – 24 (i.e., 1933 – 2017). Comparison of the model with long term observations of the Van Allen Probes and CRRES demonstrates that our model, driven by the NARX boundary, can reconstruct the general evolution of the radiation belt fluxes. Solar Cycle 24 (Jan 2008 – 2017) has been the least active of the considered solar cycles which resulted in unusually low electron fluxes. Our results show that Solar Cycle 24 should not be used as a representative solar cycle for developing long term environment models. The developed reconstruction of fluxes can be used to develop or improve empirical models of the radiation belts.This article is protected by copyright. All rights reserved. Saikin, A.; Shprits, Y; Drozdov, A; Landis, D.; Zhelavskaya, I.; Cervantes, S.; Published by: Space Weather Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020SW002524 Radiation belts; numerical modeling; Particle acceleration; Magnetosphere: inner; forecasting; Van Allen Probes |
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Determining the Temporal and Spatial Coherence of Plasmaspheric Hiss Waves in the Magnetosphere Abstract Plasmaspheric hiss is one of the most important plasma waves in the Earth s magnetosphere to contribute to radiation belt dynamics by pitch-angle scattering energetic electrons via wave-particle interactions. There is growing evidence that the temporal and spatial variability of wave-particle interactions are important factors in the construction of diffusion-based models of the radiation belts. Hiss amplitudes are thought to be coherent across large distances and on long timescales inside the plasmapause, which means that hiss can act on radiation belt electrons throughout their drift trajectories for many hours. In this study, we investigate both the spatial and temporal coherence of plasmaspheric hiss between the two Van Allen Probes from November 2012 to July 2019. We find ∼3,264 events where we can determine the correlation of wave amplitudes as a function of both spatial distance and time lag in order to study the spatial and temporal coherence of plasmaspheric hiss. The statistical results show that both the spatial and temporal correlation of plasmaspheric hiss decrease with increasing L-shell, and become incoherent at L > ∼4.5. Inside of L = ∼4.5, we find that hiss is coherent to within a spatial extent of up to ∼1,500 km and a time lag up to ∼10 min. We find that the spatial and temporal coherence of plasmaspheric hiss does not depend strongly on the geomagnetic index (AL*) or magnetic local time. We discuss the ramifications of our results with relevance to understanding the global characteristics of plasmaspheric hiss waves and their role in radiation belt dynamics. Zhang, Shuai; Rae, Jonathan; Watt, Clare; Degeling, Alexander; Tian, Anmin; Shi, Quanqi; Shen, Xiao-Chen; Smith, Andy; Wang, Mengmeng; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028635 |
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Determining the Temporal and Spatial Coherence of Plasmaspheric Hiss Waves in the Magnetosphere Abstract Plasmaspheric hiss is one of the most important plasma waves in the Earth s magnetosphere to contribute to radiation belt dynamics by pitch-angle scattering energetic electrons via wave-particle interactions. There is growing evidence that the temporal and spatial variability of wave-particle interactions are important factors in the construction of diffusion-based models of the radiation belts. Hiss amplitudes are thought to be coherent across large distances and on long timescales inside the plasmapause, which means that hiss can act on radiation belt electrons throughout their drift trajectories for many hours. In this study, we investigate both the spatial and temporal coherence of plasmaspheric hiss between the two Van Allen Probes from November 2012 to July 2019. We find ∼3,264 events where we can determine the correlation of wave amplitudes as a function of both spatial distance and time lag in order to study the spatial and temporal coherence of plasmaspheric hiss. The statistical results show that both the spatial and temporal correlation of plasmaspheric hiss decrease with increasing L-shell, and become incoherent at L > ∼4.5. Inside of L = ∼4.5, we find that hiss is coherent to within a spatial extent of up to ∼1,500 km and a time lag up to ∼10 min. We find that the spatial and temporal coherence of plasmaspheric hiss does not depend strongly on the geomagnetic index (AL*) or magnetic local time. We discuss the ramifications of our results with relevance to understanding the global characteristics of plasmaspheric hiss waves and their role in radiation belt dynamics. Zhang, Shuai; Rae, Jonathan; Watt, Clare; Degeling, Alexander; Tian, Anmin; Shi, Quanqi; Shen, Xiao-Chen; Smith, Andy; Wang, Mengmeng; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028635 |
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Determining the Temporal and Spatial Coherence of Plasmaspheric Hiss Waves in the Magnetosphere Abstract Plasmaspheric hiss is one of the most important plasma waves in the Earth s magnetosphere to contribute to radiation belt dynamics by pitch-angle scattering energetic electrons via wave-particle interactions. There is growing evidence that the temporal and spatial variability of wave-particle interactions are important factors in the construction of diffusion-based models of the radiation belts. Hiss amplitudes are thought to be coherent across large distances and on long timescales inside the plasmapause, which means that hiss can act on radiation belt electrons throughout their drift trajectories for many hours. In this study, we investigate both the spatial and temporal coherence of plasmaspheric hiss between the two Van Allen Probes from November 2012 to July 2019. We find ∼3,264 events where we can determine the correlation of wave amplitudes as a function of both spatial distance and time lag in order to study the spatial and temporal coherence of plasmaspheric hiss. The statistical results show that both the spatial and temporal correlation of plasmaspheric hiss decrease with increasing L-shell, and become incoherent at L > ∼4.5. Inside of L = ∼4.5, we find that hiss is coherent to within a spatial extent of up to ∼1,500 km and a time lag up to ∼10 min. We find that the spatial and temporal coherence of plasmaspheric hiss does not depend strongly on the geomagnetic index (AL*) or magnetic local time. We discuss the ramifications of our results with relevance to understanding the global characteristics of plasmaspheric hiss waves and their role in radiation belt dynamics. Zhang, Shuai; Rae, Jonathan; Watt, Clare; Degeling, Alexander; Tian, Anmin; Shi, Quanqi; Shen, Xiao-Chen; Smith, Andy; Wang, Mengmeng; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028635 |
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Determining the Temporal and Spatial Coherence of Plasmaspheric Hiss Waves in the Magnetosphere Abstract Plasmaspheric hiss is one of the most important plasma waves in the Earth s magnetosphere to contribute to radiation belt dynamics by pitch-angle scattering energetic electrons via wave-particle interactions. There is growing evidence that the temporal and spatial variability of wave-particle interactions are important factors in the construction of diffusion-based models of the radiation belts. Hiss amplitudes are thought to be coherent across large distances and on long timescales inside the plasmapause, which means that hiss can act on radiation belt electrons throughout their drift trajectories for many hours. In this study, we investigate both the spatial and temporal coherence of plasmaspheric hiss between the two Van Allen Probes from November 2012 to July 2019. We find ∼3,264 events where we can determine the correlation of wave amplitudes as a function of both spatial distance and time lag in order to study the spatial and temporal coherence of plasmaspheric hiss. The statistical results show that both the spatial and temporal correlation of plasmaspheric hiss decrease with increasing L-shell, and become incoherent at L > ∼4.5. Inside of L = ∼4.5, we find that hiss is coherent to within a spatial extent of up to ∼1,500 km and a time lag up to ∼10 min. We find that the spatial and temporal coherence of plasmaspheric hiss does not depend strongly on the geomagnetic index (AL*) or magnetic local time. We discuss the ramifications of our results with relevance to understanding the global characteristics of plasmaspheric hiss waves and their role in radiation belt dynamics. Zhang, Shuai; Rae, Jonathan; Watt, Clare; Degeling, Alexander; Tian, Anmin; Shi, Quanqi; Shen, Xiao-Chen; Smith, Andy; Wang, Mengmeng; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028635 |
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Determining the Temporal and Spatial Coherence of Plasmaspheric Hiss Waves in the Magnetosphere Abstract Plasmaspheric hiss is one of the most important plasma waves in the Earth s magnetosphere to contribute to radiation belt dynamics by pitch-angle scattering energetic electrons via wave-particle interactions. There is growing evidence that the temporal and spatial variability of wave-particle interactions are important factors in the construction of diffusion-based models of the radiation belts. Hiss amplitudes are thought to be coherent across large distances and on long timescales inside the plasmapause, which means that hiss can act on radiation belt electrons throughout their drift trajectories for many hours. In this study, we investigate both the spatial and temporal coherence of plasmaspheric hiss between the two Van Allen Probes from November 2012 to July 2019. We find ∼3,264 events where we can determine the correlation of wave amplitudes as a function of both spatial distance and time lag in order to study the spatial and temporal coherence of plasmaspheric hiss. The statistical results show that both the spatial and temporal correlation of plasmaspheric hiss decrease with increasing L-shell, and become incoherent at L > ∼4.5. Inside of L = ∼4.5, we find that hiss is coherent to within a spatial extent of up to ∼1,500 km and a time lag up to ∼10 min. We find that the spatial and temporal coherence of plasmaspheric hiss does not depend strongly on the geomagnetic index (AL*) or magnetic local time. We discuss the ramifications of our results with relevance to understanding the global characteristics of plasmaspheric hiss waves and their role in radiation belt dynamics. Zhang, Shuai; Rae, Jonathan; Watt, Clare; Degeling, Alexander; Tian, Anmin; Shi, Quanqi; Shen, Xiao-Chen; Smith, Andy; Wang, Mengmeng; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028635 |
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Periodic Rising and Falling Tone ECH Waves from Van Allen Probes Observations AbstractElectron cyclotron harmonic (ECH) waves are known to precipitate plasma sheet electrons into the upper atmosphere and generate diffuse aurorae. In this study, we report quasi-periodic rising (3 events) and falling tone (22 events) ECH waves observed by Van Allen Probes, and evaluate their properties. These rising and falling tone ECH waves prefer to occur during quiet geomagnetic conditions over the dusk to midnight sector in relatively high-density (10–80 cm-3) regions. Their repetition periods increase with increasing L shell at L < 6, ranging from ∼60 to 110 s. The wave element duration varies from 10 s to 130 s peaking at ∼40 s and the chirping rate peaks at ∼50 (∼-50) Hz/s for rising (falling) tones. Our findings reveal intriguing features of the ECH wave properties, which provide new insights into their generation and potential effects on electron precipitation. Shen, Xiao-Chen; Li, Wen; Ma, Qianli; Published by: Geophysical Research Letters Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020GL091330 ECH wave; falling tone; rising tone; Magnetosphere; plasma wave; Van Allen Probes |
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Abstract During geomagnetic storms, magnetospheric wave activity drives the ion precipitation which can become an important source of energy flux into the ionosphere and strongly affect the dynamics of the magnetosphere-ionosphere coupling. In this study, we investigate the role of Electro Magnetic Ion Cyclotron (EMIC) waves in causing ion precipitation into the ionosphere using simulations from the RAM-SCBE model with and without EMIC waves included. The global distribution of H-band and He-band EMIC wave intensity in the model is based on three different EMIC wave models statistically derived from satellite measurements. Comparisons among the simulations and with observations suggest that the EMIC wave model based on recent Van Allen Probes observations is the best in reproducing the realistic ion precipitation into the ionosphere. Specifically, the maximum precipitating proton fluxes appear at L = 4–5 in the afternoon-to-night sector which is in good agreement with statistical results, and the temporal evolution of integrated proton energy fluxes at auroral latitudes is consistent with earlier studies of the stormtime precipitating proton energy fluxes and vary in close relation to the SYM-H index. Besides, the simulations with this wave model can account for the enhanced precipitation of < 20 keV proton energy fluxes at regions closer to Earth (L < 5) as measured by NOAA/POES satellites, and reproduce reasonably well the intensity of <30 keV proton energy fluxes measured by DMSP satellites. It is suggested that the inclusion of H-band EMIC waves improves the intensity of precipitation in the model leading to better agreement with the NOAA/POES data. Shreedevi, P.; Yu, Yiqun; Ni, Binbin; Saikin, Anthony; Jordanova, Vania; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028553 EMIC waves; Geomagnetic storms; proton precipitation; ring current modeling; MI coupling; wave particle interaction; Van Allen Probes |
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Abstract During geomagnetic storms, magnetospheric wave activity drives the ion precipitation which can become an important source of energy flux into the ionosphere and strongly affect the dynamics of the magnetosphere-ionosphere coupling. In this study, we investigate the role of Electro Magnetic Ion Cyclotron (EMIC) waves in causing ion precipitation into the ionosphere using simulations from the RAM-SCBE model with and without EMIC waves included. The global distribution of H-band and He-band EMIC wave intensity in the model is based on three different EMIC wave models statistically derived from satellite measurements. Comparisons among the simulations and with observations suggest that the EMIC wave model based on recent Van Allen Probes observations is the best in reproducing the realistic ion precipitation into the ionosphere. Specifically, the maximum precipitating proton fluxes appear at L = 4–5 in the afternoon-to-night sector which is in good agreement with statistical results, and the temporal evolution of integrated proton energy fluxes at auroral latitudes is consistent with earlier studies of the stormtime precipitating proton energy fluxes and vary in close relation to the SYM-H index. Besides, the simulations with this wave model can account for the enhanced precipitation of < 20 keV proton energy fluxes at regions closer to Earth (L < 5) as measured by NOAA/POES satellites, and reproduce reasonably well the intensity of <30 keV proton energy fluxes measured by DMSP satellites. It is suggested that the inclusion of H-band EMIC waves improves the intensity of precipitation in the model leading to better agreement with the NOAA/POES data. Shreedevi, P.; Yu, Yiqun; Ni, Binbin; Saikin, Anthony; Jordanova, Vania; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028553 EMIC waves; Geomagnetic storms; proton precipitation; ring current modeling; MI coupling; wave particle interaction; Van Allen Probes |
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Abstract In this paper, analytical approximation is used to solve the wave equations near the plasmapause boundary layer in order to examine the validity of ray tracing approach for fast magnetosonic (MS) wave propagations, and then analytical solutions for electromagnetic fields of MS waves through the plasmapause boundary layer are provided for the first time. Both theoretical calculations from the analytical expressions and observations of Van Allen Probes have indicated that electric fields of MS waves decrease rapidly but magnetic fields increase rapidly when propagating across the plasmapause boundary layer from the outside. Considering effects of width of the plasmapause and wave frequency, parameter analysis has shown that when the width of the plasmapause boundary layer is narrow in comparison with the wavelength of MS waves, a significant part of waves will be reflected. In these circumstances, the WKB approximation and then ray tracing method might become invalid, and analytical approach provided in this paper could be utilized to solve the wave equation. Yu, Xiongdong; Yuan, Zhigang; Ouyang, Zhihai; Yao, Fei; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028330 MS waves; Radial propagation; Analytical approach; WKB approximation; Van Allen Probes |
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Abstract In this paper, analytical approximation is used to solve the wave equations near the plasmapause boundary layer in order to examine the validity of ray tracing approach for fast magnetosonic (MS) wave propagations, and then analytical solutions for electromagnetic fields of MS waves through the plasmapause boundary layer are provided for the first time. Both theoretical calculations from the analytical expressions and observations of Van Allen Probes have indicated that electric fields of MS waves decrease rapidly but magnetic fields increase rapidly when propagating across the plasmapause boundary layer from the outside. Considering effects of width of the plasmapause and wave frequency, parameter analysis has shown that when the width of the plasmapause boundary layer is narrow in comparison with the wavelength of MS waves, a significant part of waves will be reflected. In these circumstances, the WKB approximation and then ray tracing method might become invalid, and analytical approach provided in this paper could be utilized to solve the wave equation. Yu, Xiongdong; Yuan, Zhigang; Ouyang, Zhihai; Yao, Fei; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028330 MS waves; Radial propagation; Analytical approach; WKB approximation; Van Allen Probes |
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Abstract In this paper, analytical approximation is used to solve the wave equations near the plasmapause boundary layer in order to examine the validity of ray tracing approach for fast magnetosonic (MS) wave propagations, and then analytical solutions for electromagnetic fields of MS waves through the plasmapause boundary layer are provided for the first time. Both theoretical calculations from the analytical expressions and observations of Van Allen Probes have indicated that electric fields of MS waves decrease rapidly but magnetic fields increase rapidly when propagating across the plasmapause boundary layer from the outside. Considering effects of width of the plasmapause and wave frequency, parameter analysis has shown that when the width of the plasmapause boundary layer is narrow in comparison with the wavelength of MS waves, a significant part of waves will be reflected. In these circumstances, the WKB approximation and then ray tracing method might become invalid, and analytical approach provided in this paper could be utilized to solve the wave equation. Yu, Xiongdong; Yuan, Zhigang; Ouyang, Zhihai; Yao, Fei; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028330 MS waves; Radial propagation; Analytical approach; WKB approximation; Van Allen Probes |
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RBSP-ECT Combined Pitch Angle Resolved Electron Flux Data Product Abstract We describe a new data product combining pitch angle resolved electron flux measurements from the Radiation Belt Storm Probes (RBSP) Energetic Particle Composition and Thermal Plasma (ECT) suite on the National Aeronautics and Space Administration s Van Allen Probes. We describe the methodology used to combine each of the data sets and produce a consistent set of pitch-angle-resolved spectra for the entire Van Allen Probes mission. Three-minute-averaged flux spectra are provided spanning energies from 15 eV up to 20 MeV. This new data product offers researchers a consistent cross calibrated data set to explore the particle dynamics of the inner magnetosphere across a wide range of energies. This article is protected by copyright. All rights reserved. Boyd, A.J.; Spence, H.E.; Reeves, G.D.; Funsten, H.O; Skoug, R.K.; Larsen, B.A.; Blake, J.B.; Fennell, J.F.; Claudepierre, S.G.; Baker, D.N.; Kanekal, S.K.; Jaynes, A.N.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028637 |
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RBSP-ECT Combined Pitch Angle Resolved Electron Flux Data Product Abstract We describe a new data product combining pitch angle resolved electron flux measurements from the Radiation Belt Storm Probes (RBSP) Energetic Particle Composition and Thermal Plasma (ECT) suite on the National Aeronautics and Space Administration s Van Allen Probes. We describe the methodology used to combine each of the data sets and produce a consistent set of pitch-angle-resolved spectra for the entire Van Allen Probes mission. Three-minute-averaged flux spectra are provided spanning energies from 15 eV up to 20 MeV. This new data product offers researchers a consistent cross calibrated data set to explore the particle dynamics of the inner magnetosphere across a wide range of energies. This article is protected by copyright. All rights reserved. Boyd, A.J.; Spence, H.E.; Reeves, G.D.; Funsten, H.O; Skoug, R.K.; Larsen, B.A.; Blake, J.B.; Fennell, J.F.; Claudepierre, S.G.; Baker, D.N.; Kanekal, S.K.; Jaynes, A.N.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028637 |
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RBSP-ECT Combined Pitch Angle Resolved Electron Flux Data Product Abstract We describe a new data product combining pitch angle resolved electron flux measurements from the Radiation Belt Storm Probes (RBSP) Energetic Particle Composition and Thermal Plasma (ECT) suite on the National Aeronautics and Space Administration s Van Allen Probes. We describe the methodology used to combine each of the data sets and produce a consistent set of pitch-angle-resolved spectra for the entire Van Allen Probes mission. Three-minute-averaged flux spectra are provided spanning energies from 15 eV up to 20 MeV. This new data product offers researchers a consistent cross calibrated data set to explore the particle dynamics of the inner magnetosphere across a wide range of energies. This article is protected by copyright. All rights reserved. Boyd, A.J.; Spence, H.E.; Reeves, G.D.; Funsten, H.O; Skoug, R.K.; Larsen, B.A.; Blake, J.B.; Fennell, J.F.; Claudepierre, S.G.; Baker, D.N.; Kanekal, S.K.; Jaynes, A.N.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028637 |
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RBSP-ECT Combined Pitch Angle Resolved Electron Flux Data Product Abstract We describe a new data product combining pitch angle resolved electron flux measurements from the Radiation Belt Storm Probes (RBSP) Energetic Particle Composition and Thermal Plasma (ECT) suite on the National Aeronautics and Space Administration s Van Allen Probes. We describe the methodology used to combine each of the data sets and produce a consistent set of pitch-angle-resolved spectra for the entire Van Allen Probes mission. Three-minute-averaged flux spectra are provided spanning energies from 15 eV up to 20 MeV. This new data product offers researchers a consistent cross calibrated data set to explore the particle dynamics of the inner magnetosphere across a wide range of energies. This article is protected by copyright. All rights reserved. Boyd, A.J.; Spence, H.E.; Reeves, G.D.; Funsten, H.O; Skoug, R.K.; Larsen, B.A.; Blake, J.B.; Fennell, J.F.; Claudepierre, S.G.; Baker, D.N.; Kanekal, S.K.; Jaynes, A.N.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028637 |
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RBSP-ECT Combined Pitch Angle Resolved Electron Flux Data Product Abstract We describe a new data product combining pitch angle resolved electron flux measurements from the Radiation Belt Storm Probes (RBSP) Energetic Particle Composition and Thermal Plasma (ECT) suite on the National Aeronautics and Space Administration s Van Allen Probes. We describe the methodology used to combine each of the data sets and produce a consistent set of pitch-angle-resolved spectra for the entire Van Allen Probes mission. Three-minute-averaged flux spectra are provided spanning energies from 15 eV up to 20 MeV. This new data product offers researchers a consistent cross calibrated data set to explore the particle dynamics of the inner magnetosphere across a wide range of energies. This article is protected by copyright. All rights reserved. Boyd, A.J.; Spence, H.E.; Reeves, G.D.; Funsten, H.O; Skoug, R.K.; Larsen, B.A.; Blake, J.B.; Fennell, J.F.; Claudepierre, S.G.; Baker, D.N.; Kanekal, S.K.; Jaynes, A.N.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2021 YEAR: 2021 DOI: https://doi.org/10.1029/2020JA028637 |