Effect of Substorm Proton Injection On the Excitation of EMIC Waves observed by Van Allen Probes

We report simultaneous data of EMIC wave excitation and energetic proton (from 10 to 50 keV) injection observed by Van Allen Probe at L~6 during the substorm on 10 October, 2013. The EMIC waves occur at the H+ band with the intensity up to ~102 nT2/Hz, and the proton fluxes rapidly increase by 3~6 times with the strong pitch-angle anisotropy. Using the linear theory, we calculated the temperature anisotropy, the instability parameter and the EMIC growth parameter for this event base on the observational data. All those parameters are comparable to the excited conditions of EMIC waves. The current results provide further observational evidence that the substorm proton injection is the dominant mechanism responsible for exciting the EMIC waves.