Day-to-Day Variability and Predictability of the Ionosphere

Recent observational and modeling studies have revealed clear reaches of terrestrial weather far beyond the mesosphere lower thermosphere region into the topside ionosphere. At the same time, the ionosphere lends itself to forcing originating from the Sun and solar-wind magnetosphere interactions. Understanding and predicting day-to-day ionospheric variability is a major scientific challenge in space weather, and calls for a paradigm shift from a deterministic to a probabilistic modeling framework that facilitates characterization of variability and model uncertianty through multiple sensitivity simulations and systematic model-observation comparison. We will systematically compare and combine simulations of a comprehensive coupled whole atmosphere, ionosphere, and plasmasphere model with global space-based and ground-based ionospheric observations (1) to understand how the day-to-day variability of lower atmosphere wave forcing and solar and magnetospheric forcing is transformed through nonlinear coupling into the observed features of ionospheric variability; and (2) to assess the ability of Geospace observing systems to reduce model uncertainty to the extent that it has a quantifiable impact on the forecastability of the ionosphere.