# EPP

### 地球与行星物理

ISSN  2096-3955

CN  10-1502/P

Citation: Yuan, C. J., Zuo, Y. Q., Roussos, E., Wei, Y., Hao, Y. X., Sun, Y. X. and Krupp, N. (2021). Large-scale episodic enhancements of relativistic electron intensities in Jupiter's radiation belt. Earth Planet. Phys., 5(4), 314–326. http://doi.org/10.26464/epp2021037

2021, 5(4): 314-326.

PLANETARY SCIENCES

## Large-scale episodic enhancements of relativistic electron intensities in Jupiter's radiation belt

 1 Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China 2 Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 100029, China 3 University of Chinese Academy of Sciences, Beijing 100049, China 4 Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, Göttingen, 37077, Germany 5 Institute of Space Physics and Applied Technology, Peking University, Beijing 100871, China

Corresponding author: Elias Roussos, roussos@mps.mpg.de

Web Publishing Date: 2021-06-18

Previous studies indicate that, in the Jovian magnetosphere, the long-term trend of the radial profile of relativistic electron intensities is primarily shaped by slow radial diffusion. However, measurements by the Galileo spacecraft reveal the existence of transient increases in MeV electron intensities well above the ambient distribution. It is unclear how common such transient enhancements are, and to which dynamic processes in Jupiter's magnetosphere their occurrence is linked. We investigate the radial distributions of $>$11 MeV and $>$1 MeV electron intensities from $9R_{J}$ to $40R_{J}$ ($R_{J}=71492\;{\rm{km}}$ denotes the Jovian radius), measured by the Galileo spacecraft from 1996 to 2002. We find transient enhancements of MeV electrons during seven Galileo crossings, mostly occurring around ~20RJ. An apparent dawn-dusk asymmetry of their occurrence is resolved, with a majority of events discovered at dawn. This dawn-dusk asymmetry, as well as the average recurrence time scale of a few days, implies a potential relationship between the MeV electron transients and the storm-like dynamics in the middle and outer magnetosphere detected using a variety of Galileo, Juno and remote sensing aurora observations. We suggest that the observations of some of these transients in the inner magnetosphere may result from a synergy between the convective transport by a large-scale dawn-dusk electric field and the sources provided by injections in the middle magnetosphere.