We investigate the characteristics of impulsive electric fields in the Earth's magnetosphere, as measured by the Van Allen Probes, in association with interplanetary shocks, as measured by Advanced Composition Explorer and Wind spacecraft in the solar wind from January 2013 to July 2016. It is shown that electric field impulses are mainly induced by global compressions by the shocks, mostly in the azimuthal direction, and the amplitudes of the initial electric field impulses are positively correlated with the rate of increase of the dynamic pressure across the shock in the dayside. It is also shown that the temporal profile of the impulse is related to the temporal profile of the solar wind dynamic pressure, Pd. It is suggested that during the first period of the impulse, the evolution of the electric field is directly controlled by external solar wind forcing, and thus, finite rates of change of Pd should be considered in the study of the interactions between solar wind and magnetosphere. The implications of shock-induced impulsive electric fields on the acceleration and transport of radiation belt electrons are also discussed.
Bibliographical noteFunding Information:
This work was supported by National Natural Science Foundation of China grant 41574154. This work was also partially supported by NASA/RBSP-EFW funding through JHU/APL contract 967399 under prime National Aeronautics and Space Administration contract NAS5-01072. We thank the Electric Field and Waves instrument and the Electric and Magnetic Field Instrument Suite and Integrated Science instrument teams of the Van Allen Probes mission for making data avail able. Van Allen Probes data, solar wind parameters, and geomagnetic indices are obtained from the Coordinated Data Analysis Web (CDAWeb) (cdaweb.sci. gsfc.nasa.gov). The event list of IPSs used in this study is adopted from the Heliospheric Shock Database main tained by the University of Helsinki (www.ipshocks.fi/database).
- electric field
- inner magnetosphere
- interplanetary shock
- particle acceleration