Biblio

Found 7 results
Filters: Author is Rae, I. J.  [Clear All Filters]
2019
Authors: Mann I. R., Ozeke L. G., Morley S. K., Murphy K. R., Claudepierre S G, et al.
Title: Reply to 'The dynamics of Van Allen belts revisited'
Abstract: N/A
Date: 02/2019 Publisher: Nature Physics Pages: 103 - 104 DOI: 10.1038/nphys4351 Available at: http://www.nature.com/doifinder/10.1038/nphys4351
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Authors: Sandhu J. K., Rae I. J., Freeman M. P., Gkioulidou M., Forsyth C., et al.
Title: Substorm‐Ring Current Coupling: A Comparison of Isolated and Compound Substorms
Abstract: Substorms are a highly variable process, which can occur as an isolated event or as part of a sequence of multiple substorms (compound substorms). In this study we identify how the low‐energy population of the ring current and subsequent energization varies for isolated substorms compared to the first substorm of a compound event. Using observations of H+ and O+ ions (1 eV to 50 keV) from the Helium Oxygen Proton Electron instrument onboard Van Allen Probe A, we determine the energy content of the ring current in L‐MLT space. We observe that the ring current energy content is significantly enhanced during compound substorms as compared to isolated substorms by ∼20–30%. Furthermore, we observe a significantly larger magnitude of energization (by ∼40–50%) following the onset of c. . .
Date: 08/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 6776 - 6791 DOI: 10.1029/2019JA026766 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026766
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Authors: Watt C. E. J., Allison H. J., Meredith N P, Thompson R. L., Bentley S. N., et al.
Title: Variability of Quasilinear Diffusion Coefficients for Plasmaspheric Hiss
Abstract: In the outer radiation belt, the acceleration and loss of high‐energy electrons is largely controlled by wave‐particle interactions. Quasilinear diffusion coefficients are an efficient way to capture the small‐scale physics of wave‐particle interactions due to magnetospheric wave modes such as plasmaspheric hiss. The strength of quasilinear diffusion coefficients as a function of energy and pitch angle depends on both wave parameters and plasma parameters such as ambient magnetic field strength, plasma number density, and composition. For plasmaspheric hiss in the magnetosphere, observations indicate large variations in the wave intensity and wave normal angle, but less is known about the simultaneous variability of the magnetic field and number density. We use in situ measurements. . .
Date: 10/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026401 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026401
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2018
Authors: Sandhu J. K., Rae I. J., Freeman M. P., Forsyth C., Gkioulidou M., et al.
Title: Energisation of the ring current by substorms
Abstract: The substorm process releases large amounts of energy into the magnetospheric system, although where the energy is transferred to and how it is partitioned remains an open question. In this study, we address whether the substorm process contributes a significant amount of energy to the ring current. The ring current is a highly variable region, and understanding the energisation processes provides valuable insight into how substorm ‐ ring current coupling may contribute to the generation of storm conditions and provide a source of energy for wave driving. In order to quantify the energy input into the ring current during the substorm process, we analyse RBSPICE and HOPE ion flux measurements for H+, O+, and He+. The energy content of the ring current is estimated and binned spatially for. . .
Date: 09/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025766 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025766
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2016
Authors: Mann I. R., Ozeke L. G., Murphy K. R., Claudepierre S G, Turner D. L., et al.
Title: Explaining the dynamics of the ultra-relativistic third Van Allen radiation belt
Abstract: Since the discovery of the Van Allen radiation belts over 50 years ago, an explanation for their complete dynamics has remained elusive. Especially challenging is understanding the recently discovered ultra-relativistic third electron radiation belt. Current theory asserts that loss in the heart of the outer belt, essential to the formation of the third belt, must be controlled by high-frequency plasma wave–particle scattering into the atmosphere, via whistler mode chorus, plasmaspheric hiss, or electromagnetic ion cyclotron waves. However, this has failed to accurately reproduce the third belt. Using a datadriven, time-dependent specification of ultra-low-frequency (ULF) waves we show for the first time how the third radiation belt is established as a simple, elegant consequence o. . .
Date: 06/2016 Publisher: Nature Physics DOI: 10.1038/nphys3799 Available at: http://www.nature.com/doifinder/10.1038/nphys3799
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Authors: Forsyth C., Rae I. J., Murphy K. R., Freeman M. P., Huang C.-L., et al.
Title: What effect do substorms have on the content of the radiation belts?
Abstract: Substorms are fundamental and dynamic processes in the magnetosphere, converting captured solar wind magnetic energy into plasma energy. These substorms have been suggested to be a key driver of energetic electron enhancements in the outer radiation belts. Substorms inject a keV “seed” population into the inner magnetosphere which is subsequently energized through wave-particle interactions up to relativistic energies; however, the extent to which substorms enhance the radiation belts, either directly or indirectly, has never before been quantified. In this study, we examine increases and decreases in the total radiation belt electron content (TRBEC) following substorms and geomagnetically quiet intervals. Our results show that the radiation belts are inherently lossy, shown by a negat. . .
Date: 06/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022620 Available at: http://doi.wiley.com/10.1002/2016JA022620
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2013
Authors: Mann Ian R., Lee E. A., Claudepierre S G, Fennell J. F., Degeling A., et al.
Title: Discovery of the action of a geophysical synchrotron in the Earth’s Van Allen radiation belts
Abstract: Although the Earth’s Van Allen radiation belts were discovered over 50 years ago, the dominant processes responsible for relativistic electron acceleration, transport and loss remain poorly understood. Here we show evidence for the action of coherent acceleration due to resonance with ultra-low frequency waves on a planetary scale. Data from the CRRES probe, and from the recently launched multi-satellite NASA Van Allen Probes mission, with supporting modeling, collectively show coherent ultra-low frequency interactions which high energy resolution data reveals are far more common than either previously thought or observed. The observed modulations and energy-dependent spatial structure indicate a mode of action analogous to a geophysical synchrotron; this new mode of response represents . . .
Date: 11/2013 Publisher: Nature Communications DOI: 10.1038/ncomms3795 Available at: http://www.nature.com/doifinder/10.1038/ncomms3795
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