Biblio

Found 3 results
Filters: Author is Cattell, Cynthia A.  [Clear All Filters]
2015
Authors: Dai Lei, Wang Chi, Duan Suping, He Zhaohai, Wygant John R., et al.
Title: Near-Earth Injection of MeV Electrons associated with Intense Dipolarization Electric Fields: Van Allen Probes observations
Abstract: Substorms generally inject 10s-100s keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeV electron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the pre-midnight sector at L∼5.5, Van Allen Probes (RBSP)-A observed a large dipolarization electric field (50mV/m) over ∼40s and a dispersionless injection of electrons up to ∼3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front. Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the in. . .
Date: 07/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL064955 Available at: http://doi.wiley.com/10.1002/2015GL064955
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Authors: Dai Lei, Takahashi Kazue, Lysak Robert, Wang Chi, Wygant John R., et al.
Title: Storm-time occurrence and Spatial distribution of Pc4 poloidal ULF waves in the inner magnetosphere: A Van Allen Probes Statistical study
Abstract: Poloidal ULF waves are capable of efficiently interacting with energetic particles in the ring current and the radiation belt. Using Van Allen Probes (RBSP) data from October 2012 to July 2014, we investigate the spatial distribution and storm-time occurrence of Pc4 (7-25 mHz) poloidal waves in the inner magnetosphere. Pc4 poloidal waves are sorted into two categories: waves with and without significant magnetic compressional components. Two types of poloidal waves have comparable occurrence rates, both of which are much higher during geomagnetic storms. The non-compressional poloidal waves mostly occur in the late recovery phase associated with an increase of Dst toward 0, suggesting that the decay of the ring current provides their free energy source. The occurrence of dayside compressio. . .
Date: 05/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021134 Available at: http://doi.wiley.com/10.1002/2015JA021134
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2014
Authors: Dai Lei, Wygant John R., Cattell Cynthia A., Thaller Scott, Kersten Kris, et al.
Title: Evidence for injection of relativistic electrons into the Earth's outer radiation belt via intense substorm electric fields
Abstract: Observation and model results accumulated in the last decade indicate that substorms can promptly inject relativistic ‘killer’ electrons (≥MeV) in addition to 10–100 keV subrelativistic populations. Using measurements from Cluster, Polar, LANL, and GOES satellites near the midnight sector, we show in two events that intense electric fields, as large as 20 mV/m, associated with substorm dipolarization are associated with injections of relativistic electrons into the outer radiation belt. Enhancements of hundreds of keV electrons at dipolarization in the magnetotail can account for the injected MeV electrons through earthward transport. These observations provide evidence that substorm electric fields inject relativistic electrons by transporting magnetotail electrons into the outer . . .
Date: 02/2014 Publisher: Geophysical Research Letters Pages: 1133 - 1141 DOI: 10.1002/2014GL059228 Available at: http://doi.wiley.com/10.1002/2014GL059228
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