The most unpredictable space weather events are substorms, periods of energy loading and explosive release within the nightside of the Earth, resembling solar eruptions.
Substorms are a major open question in space physics, with several decades-long debates:
- Where, when, and why does the substorm onset occur,
- Does it need a trigger, and
- What is the role of the ionosphere in the process?
Vlasiator is the world’s most accurate space environment simulation, recently extended to encompass the solar wind – magnetosphere system in 3D.
First 3D runs already exist, carried out using steady solar wind conditions and using a conducting sphere for the ionosphere. In 2021 a fully dynamic ionosphere and time-varying solar wind conditions were integrated in Vlasiator.
The existing runs and the new capabilities will make it possible, for the first time, to establish
- the cause for the substorm onset,
- whether the solar wind trigger plays a role, and via comparison with the previous runs,
- the role of the dynamic ionosphere in substorm dynamics.
Violent eruptions are universal, occurring at the Sun and other planetary magnetospheres, yet only near the Earth can the processes be researched with novel modelling tools validated by spacecraft constellations.