The Effects of Magnetospheric Processes on Relativistic Electron Dynamics in the Earth

The effects of magnetospheric processes on relativistic electron dynamics in the Earth’s outer radiation belt

C. L. Tang1, 2, Y. X. Wang2, B. Ni3, Z. P. Su4,G. D. Reeves5, J.-C. Zhang6, D. N. Baker7,H. E. Spence6, H. O. Funsten5, and J. B. Blake8

1Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, China,

2Sate Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing, China,

3Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan, China,

4CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary

Sciences, University of Science and Technology of China, Hefei, Anhui, China,

5ISR Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA,

6Space Science Center and Department of Physics, University of New Hampshire, Durham, New Hampshire, USA,

7Laboratoryfor Atmospheric and Space Research, University of Colorado, Boulder, Colorado, USA,

8The Aerospace Corporation, Los Angeles, California, USA.

Abstract Using the electron phase space density (PSD) data measured by Van Allen Probe A from January 2013 to April 2015, we investigate the effects ofmagnetospheric processes on relativistic electron dynamics in the Earth’s outer radiation belt during 50 geomagnetic storms. The statistical study shows that the maximum electron PSDs for various μ (μ=630, 1096, 2290, and 3311 MeV/G) atL*~4.0 after the storm peak have good correlations with storm intensity (cc~0.70).This suggests that the occurrence and magnitude of geomagnetic storms are necessary forrelativistic electron enhancements at the inner edge of the outer radiation belt (L*=4.0).For moderate or weak storm events (SYM-Hmin>~–100 nT) with weak substorm activity (AEmax800 nT)and strong storm events (SYM-Hmin~–100 nT) with intensive substorms(AEmax800 nT) during the recovery phase, the maximumelectron PSDs for various μ atdifferent L* values(L*=4.0, 4.5 and 5.0)are well correlated with storm intensity(cc0.77). For storm events with intensive substorms after the storm peak, relativistic electron enhancements at L*=4.5 and 5.0 are observed.This shows that intensive substorms during the storm recovery phase are crucial for relativistic electron enhancements in the heart of the outer radiation belt. Our statisticsstudy suggests that magnetospheric processes during geomagnetic stormshave significanteffect on relativistic electron dynamics.