Abstract
Plasmaspheric hiss was observed by Van Allen Probe B in association with energetic electron injections in the outer plasmasphere. The energy of injected electrons coincides with the minimum resonant energy calculated for the observed hiss wave frequency. Interestingly, the variations in hiss wave intensity, electron flux and ultra low frequency (ULF) wave intensity exhibit remarkable correlations, while plasma density is not correlated with any of these parameters. Our study provides direct evidence for the first time that the injected anisotropic electron population, which is modulated by ULF waves, modulates the hiss intensity in the outer plasmasphere. This also implies that the plasmaspheric hiss observed by Van Allen Probe B in the outer plasmasphere (L > ∼ 5.5) is locally amplified. Meanwhile, Van Allen Probe A observed hiss emission at lower L shells (< 5), which was not associated with electron injections but primarily modulated by the plasma density. The features observed by Van Allen Probe A suggest that the observed hiss deep inside the plasmasphere may have propagated from higher L shells.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 781-791 |
| Number of pages | 11 |
| Journal | Annales Geophysicae |
| Volume | 36 |
| Issue number | 3 |
| DOIs | |
| State | Published - May 23 2018 |
Bibliographical note
Funding Information:Acknowledgements. The work at Boston University is supported by the NASA grants NNX15AI96G, NNX17AG07G, and NNX17AD15G and the NSF grant AGS-1723342. The research at the University of Minnesota was supported by JHU/APL contract UMN 922613 under NASA contract JHU/APL NAS5-01072. We acknowledge the RBSP-ECT and EMFISIS funding provided by JHU/APL contract nos. 967399 and 921647 under NASA’s prime contract no. NAS5-01072. We would like to thank Lei Dai and Xu-Zhi Zhou for very helpful discussions in this study. We would like to acknowledge the EMFISIS data obtained from https://emfisis. physics.uiowa.edu/data/index, the MagEIS data obtained from http: //www.rbsp-ect.lanl.gov/science/DataDirectories.php, and the EFW data obtained from http://rbsp.space.umn.edu/data/rbsp/ (last access: 24 April 2018). We also thank the World Data Center for Geomagnetism, Kyoto for providing the AE index used in this study.
Funding Information:
The work at Boston University is supported by the NASA grants NNX15AI96G, NNX17AG07G, and NNX17AD15G and the NSF grant AGS-1723342. The research at the University of Minnesota was supported by JHU/APL contract UMN 922613 under NASA contract JHU/APL NAS5-01072. We acknowledge the RBSP-ECT and EMFISIS funding provided by JHU/APL contract nos. 967399 and 921647 under NASA's prime contract no. NAS5-01072. We would like to thank Lei Dai and Xu- Zhi Zhou for very helpful discussions in this study. We would like to acknowledge the EMFISIS data obtained from https://emfisis. physics.uiowa.edu/data/index, the MagEIS data obtained from http: //www.rbsp-ect.lanl.gov/science/DataDirectories.php, and the EFW data obtained from http://rbsp.space.umn.edu/data/rbsp/ (last access: 24 April 2018). We also thank the World Data Center for Geomagnetism, Kyoto for providing the AE index used in this study. The topical editor, Minna Palmroth, thanks two anonymous referees for help in evaluating this paper.
Publisher Copyright:
© 2018 Author(s).