Simulation on the IMF Bz control of the whistler mode wave excitation associated with the high-speed coronal hole streams

Electron flux of the outer belt tends to increase when the high-speed solar wind interacts with the magnetosphere. The flux enhancement depends not only on the solar wind speed but also on the offset in the north-south component of the interplanetary magnetic field, i.e. the southward offset causes larger flux enhancement than the northward offset, although large-amplitude Alfvenic fluctuations always exist in the high-speed solar wind. If the acceleration process of the outer-belt electrons via the whistler-wave particle interaction is dominant, the populations of hot electrons, plasmasphere, and whistler waves enhance all together during the SBz stream, while they weakens all together during the NBz stream. We have observationally shown the north-south IMF dependence. In this study, we use the relativistic-RAM electron model to confirm the north-south IMF dependences of the key parameters. The data measured by LANL/MPA is used as a boundary condition at L=6.6. As a result, in the SBz stream, there are enhancements of hot electrons of ~30 keV and lower-band whistler mode waves around L=4 at dawn-side, while they are at L>5 in the NBz stream. It is found that, in our simulations, these differences are primarily originated from the magnetospheric convection. It is also found that the plasma sheet temperature in the SBz stream is higher than that in the NBz stream, but the difference in the plasma sheet temperature do not essentially play important role to excite the whistler waves. We further discuss a new methodology to dynamically include the results of cutting-edge particle simulation which self-consistently reproduce the non-linear evolution of chorus waves.