Statistical characteristics of the EMIC wave propagation obtained from conjugate observations between space and ground

Abstract:

Electromagnetic ion cyclotron (EMIC) waves have long been known to play a critical role in both radiation belt and ring current dynamics. EMIC waves are generated by the anisotropic proton velocity distribution near the equator and propagate parallel to the background magnetic field. A long history of ground observations has provided solid scientific understanding of EMIC waves which are also known as Pc1-2 waves. However, satellite measurements of EMIC waves often show different characteristics from ground observations. For example, EMIC waves observed on the ground appear to persist over longer hours while only the snapshot of such waves are observed by fast-moving spacecraft. Their spectral features such as wave power and polarization senses often change during propagation. In this presentation, we statistically investigate EMIC waves using a magnetically conjugate ground station and satellite pair. For ground observations, we utilize the search coil magnetometer at Sanikiluaq station (SNK, 56.32˚N, 280.86˚E). The fluxgate magnetometer on GOES 13 (at geosynchronous orbit, 285˚E) provides data near the wave source region. We statistically compare wave properties between the observations from the GOES 13 and SNK station. We also investigate what plasma states and geomagnetic conditions control wave propagation.