Electric Fields Measured by MMS and Van Allen Probes in the Inner Magnetosphere

The electric field is a key quantity in the inner magnetosphere to determine particle motion. More data are recently accumulated by the Magnetospheric Multiscale (MMS) and Van Allen Probes missions. The MMS mission carries two electric field instruments, the Electron Drift Instrument (EDI) and the Electric field Double Probe (EDP) instrument, while the Van Allen Probes mission carries one, the Electric Fields and Waves (EFW) instrument. The orbit of MMS precesses once per year, while that of Van Allen Probes precesses once per two years. Therefore, close conjunctions in magnetic local times (MLTs) and L values occasionally take place. We will compare electric fields measured by the above three instruments and provide their implications on dynamics of the inner magnetosphere, including the region coupled to the subauroral ionosphere.