The science of space weather is concerned with understanding the causes and effects of varying conditions in mainly the Earth's magnetosphere and atmosphere that are mostly driven by the Sun. The solar wind is a supersonic flow of an extremely fast and tenuous plasma that is expelled by the Sun at all times, and interacts with other solar system objects such as planets, comets and asteroids. It carries a magnetic field that is shaped like a spiral due to the rotation of the Sun. Normally, the so-called slow solar wind, which nevertheless impacts Earth with 400 kilometres per second, flows quietly around the Earth's magnetic field. However, during time intervals of strong southward magnetic fields and higher solar wind speeds, which are caused by solar storms (known as coronal mass ejections) and fast solar wind streams, energy is transferred into the magnetosphere and the magnetic field of the Earth is temporarily disturbed.
The prediction of the solar wind impacting the Earth's magnetic field is a major unsolved problem in space science. An accurate solar wind forecast would tell us where and when the aurora lights up the sky, or whether power grids in countries at high latitudes such as Canada or Norway are at risks of failure.
IWF is working on solar wind predictions for high-speed streams and coronal mass ejections, with numerical, analytical and empirical models. Particularly the runtime of the models is optimized, so that ensemble simulations with variations in the input parameters can be produced in order to estimate error bars in the predictions, and to make it possible to apply the models in real-time.
The team members combine observations from as many spacecraft as possible, including Solar Orbiter and BepiColombo, in order to gain a complete picture of how solar storms and high speed solar wind streams propagate from the Sun to the planets. To this end we are working on a complete Sun-to-Earth chain of our self-developed models, covering the background solar wind and solar storms to predict the solar wind near Earth. Then it is calculated how the errors in the solar wind prediction affect the forecasts of geomagnetic indices, ground-induced currents and the aurora location.