Specification of the Earth's Plasmasphere with Data Assimilation

The plasmasphere is an important component of the intricate web of interacting processes which cause and are space weather. It is the medium of propagation for waves which are responsible for acceleration and decay of the radiation belts, it causes surface charging, and even affects orbital decay. Although the time-scales in the plasmasphere are significantly larger than for many other magnetospheric regions, the plasmasphere still exhibits significant dynamics, and capturing these dynamics is important in predicting the effects of the plasmasphere. In this paper we will discuss using data assimilation techniques to model the plasmasphere. In particular we will explore using a simple plasmasphere model (Ober et al., 1997) in combination with ensemble Kalman filtering techniques (e.g. Evensen, 2003). The ultimate goal is to produce a physics-based model in which only unknown external inputs are adjusted to maximize agreement between model and data. We will discuss data sources as well as progress to date.