EMIC wave induced proton precipitation : Comparison of BATSRUS+RAM-SCB simulations with multi-instrument observations

Abstract:

Electro Magnetic Ion Cyclotron (EMIC) waves are known to initiate the ion precipitation into the mid latitude ionosphere during geomagnetic storms. Recent studies have shown that the EMIC wave induced ion precipitation can contribute significantly to the total energy flux deposition into the ionosphere and severely affect the magnetosphere-ionosphere coupling. During the geomagnetic storm of 27-28 May 2017, the Van Allen Probes satellite observed typical signatures of EMIC waves in the inner magnetosphere i.e., at 4 to 6 Re in the afternoon sector. The particle measurements from the DMSP satellites show the presence of enhanced proton precipitation at ionospheric altitudes during the storm. The temporal and spatial evolution of the proton precipitation into the ionosphere and its correspondence to the EMIC wave activity in the inner magnetosphere is examined using simulations from the BATSRUS+RAM-SCB model. The plasma source and distributions of associated temperature anisotropy in the equatorial plane are investigated to understand the excitation of the waves. The subsequent global distribution of the precipitating proton fluxes obtained from the simulations are compared with the particle measurements from the DMSP and NOAA/POES observations. This study highlights the importance of wave-particle interaction in the spatio-temporal evolution of the ion precipitation in the mid latitude ionosphere.