Modeling the Earth's Inner Magnetosphere

Abstract: 

The Earth's magnetosphere covers a vast region of space that is dominated by the Earth's magnetic field. It is a highly dynamic system that responds nonlinearly to driving by the time-varying solar wind. Conditions in space may turn quickly from quiet to destructive and geomagnetic disturbances may last for days. The near-Earth inner magnetosphere, where many of the nation's civilian and military space assets operate, is one of the most hazardous regions of space in which spacecraft damage and failure could arise. The largest variations in the inner magnetospheric plasma and fields occur during geomagnetic storms and are related to the intensification of the ring current, the magnetically trapped charged particles circling Earth between ~2 to 5 Earth radii. 

Global modeling is a powerful tool to study the storm-time dynamics of the coupled inner magnetosphere. We present simulations from the Ring current-Atmosphere interactions Model with Self-Consistent magnetic (B) field (RAM-SCB) developed as part of the SHIELDS framework at LANL. We investigate the acceleration and loss of energetic particles as they are transported from the magnetotail to the inner magnetosphere during several geomagnetic storms. We find increased anisotropies in the ion and electron velocity distributions due to particle injections and energy dependent drifts and losses. These unstable distributions induce the growth of plasma waves which further affect the near-Earth radiation environment. Model results are compared with in situ plasma and field observations and implications for future model development and new research are discussed.