Electromagnetic ion cyclotron (EMIC) waves in the Pc1-2 frequency range (0.1–5 Hz) are generated by unstable ion distributions in the Earth’s magnetosphere owing to magnetospheric compressions or magnetotail particle injections. These waves play a major role in the Earth’s magnetospheric dynamics especially in the radiation belts. They contribute to the ring current ion and relativistic electron loss during geomagnetic storm times. However, the relationship of EMIC wave occurrence to geomagnetic storm and non storm periods and to storm phases has not been found to be consistent. This shall be the topic of the proposed team work. Several studies have characterized the occurrence of EMIC waves by geomagnetic indices, however, only a few, for example Halford et al., 2016, have studied the variation of EMIC wave occurrence versus different storm phases in conjunction with SymH, Kp and AE indices. The physics behind the generation of EMIC waves and eventually the loss of particles by these waves differ during different storm phases. Hence, it is extremely important to understand the EMIC wave occurrence and typical wave and plasma parameters during various storm phases.
The proposed focus group will bring together theorists, simulators, and observationalists to predict when and where the waves should occur for verification by large statistical study preliminarily using Van Allen Probes observations. The team will focus on understanding the storm phase dependence of the EMIC waves and relevant plasma parameters, along with their dependence on various geomagnetic indices and solar wind parameters, and incorporate the results in global numerical simulations. Our aim is to build on the existing understanding of the strong geomagnetic activity and storm phase dependence of EMIC waves and bring together the wave and plasma dynamics in order to construct a comprehensive picture of magnetospheric dynamics. We will do so by comparing our results with all other available in-situ EMIC wave data, past and present (and future), for example, CRRES which was the predecessor to the Van Allen Probes with a very similar orbit and set of instrumentation, but precessed through the Earth’s magnetosphere during a very active solar cycle, THEMIS which has a wider radial (L shell) coverage, CLUSTER which has a polar orbit covering wider latitudes, AMPTE with similar orbits as Van Allen Probes which precessed during the ascent of solar cycle 22 and Japan’s recently launched ARASE (ERG), another mission with orbits similar to Van Allen Probes. The choice of the data sets/mission will largely depend on the availability of the measured plasma parameters. The new results will help us better understand the role of EMIC waves in the radiation belt dynamics with respect to the storms and storm phases during varied solar cycle activity. This study will greatly enhance our capability to model EMIC wave effects in global simulations. Finally, we will compile a state-of-art review article incorporating the new results.