Upper Limit of Electron Fluxes Observed in the Radiation Belts

Authors

• Kun Zhang, University of Colorado BoulderFollow
• Xinlin Li, University of Colorado Boulder
• Hong Zhao, University of Colorado Boulder
• Zheng Xiang, University of Colorado Boulder
• Leng Ying Khoo, University of Colorado Boulder
• Wenxun Zhang, University of Colorado Boulder
• Benjamin Hogan, University of Colorado Boulder
• Michael A. Temerin, University of California, Berkeley

Submitting Campus

Daytona Beach

Department

Physical Sciences

Document Type

Article

Publication/Presentation Date

12-15-2020

Abstract/Description

Radiation belt electrons have a complicated relationship with geomagnetic activity. We select electron measurements from 7 years of DEMETER and 6 years of Van Allen Probes data during geomagnetic storms to conduct statistical analysis focusing on the correlation between electron flux and Dst index. We report, for the first time, an upper limit of electron fluxes observed by both satellites throughout the inner and outer belts across a wide energy range from ∼100s keV to multi-MeV. The upper flux limit is determined at different L's and energies, for example, 1.9 × 107/cm2-s-sr-MeV at 470 keV at L = 1.5 and 3.6 × 105/cm2-s-sr-MeV at 3.4 MeV at L = 4 (Van Allen Probes). We present the energy spectra of the electron flux upper limit at different L shells and find the measured upper flux limit to be at least three times higher than the predicted flux from the AE8/AE9 models, although the spectral shape is remarkably similar. We show that the average flux with an applied time lag is better correlated with the Dst index and that the time lag optimizing the correlation coefficient is larger at lower L and at higher energies. These findings present the underlying challenges to model the dynamic variation of relativistic electrons in the inner magnetosphere and are important information for space weather considerations.

Publication Title

Journal of Geophysical Research: Space Physics

DOI

https://doi.org/10.1029/2020JA028511

Publisher

John Wiley & Sons, Inc

Grant or Award Name

NSF grant AGS 1834971 and NASA grants NNX17AD85G and 80NSSC17K0429, and by NASA/RBSPECT funding through JHU/APL contract 967399 under prime NASA contract NAS5- 01072, NSFC grant 41904143 and the China Postdoctoral Science Foundation Project 2019M662700

Additional Information

Dr. Zhang was not affiliated with Embry-Riddle Aeronautical University at the time this paper was published.

Scholarly Commons Citation

Zhang, K., Li, X., Zhao, H., Xiang, Z., Khoo, L. Y., Zhang, W., et al. (2021). Upper limit of electron fluxes observed in the radiation belts. Journal of Geophysical Research: Space Physics, 126, e2020JA028511. https://doi. org/10.1029/2020JA028511