We are developing the semi-empirical model 3DCORE for the solar storm magnetic core. An interactive software has been built as a front end, which allows, for the first time, to receive immediate feedback on changing parameters of the model manually. Automatically, 3DCORE can produce ensemble runs, checking many outcomes of the model by making a large number of runs with slightly varying parameters. Our model can make those runs in such a short time that it can compute forecasts in real-time as the solar storm is sweeping over the Earth.
However, we need to figure out if the model represents well how a solar storm magnetic field looks in 3D in the heliosphere. For using the simulation for forecasting solar storms at Earth, we need to know how to set its parameters in the best way possible. We have applied the simulation to solar storms that have been observed by both the Parker Solar Probe and Solar Orbiter, or both at STEREO-A and the Wind spacecraft near Earth. The main result is that a newly developed deformable model version describes the data better than a more rigid shape. We have also made simulations for probing the structure of the 3DCORE model, with synthetic spacecraft that fly through the model at different positions. We found that flank encounters that often show constant components of the magnetic field can be explained by a very low twist of this field, which is a major result for improving both solar storm forecasting.
Due to high solar activity and the fortunate placement of spacecraft orbits with respect to Earth, we have used STEREO-A and Solar Orbiter for analyses of how to use in situ data from closer to the Sun to improve the forecast accuracy and lead time. We have made the first real-time prediction of the geomagnetic effects of a solar storm with Solar Orbiter in March 2024. With STEREO-A we are testing the feasibility of a possible future spacecraft mission on a distant retrograde orbit, in which one of several spacecraft would always be in between the Sun and Earth to provide in situ data for warnings with longer lead time. On 10 May 2024, STEREO-A saw a solar superstorm arrive 2.5 hours before its arrival at Earth, and we informed the public worldwide through social media, and through classical media in central Europe, that a strong solar storm is imminent, which turned out to be the strongest geomagnetic storm in 20 years. An analysis of the interaction of the five solar storms involved in this event is ongoing.
