While we experience the changes of weather every day, most people are not even aware of the dynamic changes of the Sun and its effects on Earth and spacecraft. Space weather describes the various processes in the Sun-Earth system that present danger to human health and technology. Space weather forecasting aims at providing an opportunity to mitigate these negative effects. The University of Michigan has been at the forefront of physics-based space weather modeling. We have developed a flexible and efficient magnetohydrodynamic (MHD) model, the Block-Adaptive Tree Solarwind Roe-type Upwind Scheme (BATS-R-US) code that we use to model the solar convection zone, solar corona, the heliosphere, the magnetosphere around the Earth and other planets, moons and comets. MHD, even with many extensions, is not a valid approximation in many domains of the space weather system. Examples of non-MHD models include the Global Ionosphere-Thermosphere Model (GITM) that simulates the ionized and neutral gases in the upper atmosphere, the Ridley Ionosphere Model (RIM) that solves for the electric potential field in the ionosphere, the Polar Wind Outflow Model (PWOM) that solves for the ions escaping into the magnetosphere along open magnetic field lines and the inner magnetosphere and radiation belt models that describe the high-energy particles trapped on closed field lines. While all of these models were developed independently, they need to be coupled together to represent the space weather system.
The Space Weather Modeling Framework (SWMF) was developed to efficiently couple a subset of the various physics domain models and execute them faster than real time on large parallel computers. The publicly available SWMF is distributed with a full set of domain models. The Community Coordinated Modeling Center (CCMC) at NASA Goddard provides access to the SWMF via runs-on-request. The CCMC also runs the magnetospheric models of the SWMF in real time and has been providing now-casting for many years. The CCMC also performs SWMF-based coronal-heliospere simulations, which predict solar wind conditions at Earth.