The Sun is constantly blowing plasma — a sea of charged particles — at speeds of up to a million kilometres per hour or more. This plasma, called the solar wind, bombards Earth with massive amounts of protons, electrons and ionised atoms. These can pierce the Earth's magnetosphere, the protective invisible shield surrounding our planet. A massive influx of charged particles with their impact on the Earth magnetic field would debilitate power grids, disrupt communications networks and damage electronic devices. The 'Space weather integrated forecasting framework' (SWIFF) project was set up to provide a better understanding of how solar wind and solar storms affect the Earth's magnetosphere and produce space weather effects called magnetic storms. Getting the details of space weather right means capturing everything from the Earth-sized magnetic field — some 1.28 million km across — right down to individual sub-atomic electrons drifting along magnetic field lines, and everything in between. For better mapping, the SWIFF project scientists coupled kinetic and fluid models. In local simulations, electrons and ions were primarily treated as individual particles in regions of the magnetosphere where magnetic reconnection is known to occur. During the process of magnetic reconnection, magnetic field lines in one direction suddenly break and reconnect with lines in the opposite direction, causing an explosive release of energy. This allowed scientists to home in on the most relevant interactions. SWIFF researchers used these details to improve computational models of magnetic reconnection in global simulations, which encompass the entire Earth's magnetosphere. At this scale, the electrons were no longer simulated as individual particles; rather, they were treated as a fluid. Lastly, with improved predictive capabilities, the models were extended to consider disturbances arriving from the Sun. These efforts showed how dynamic the entire system is. The new tools developed can be used to infer what is occurring deep in the Earth's space environment. Besides a deeper understanding, this process helps predicting solar storms more accurately.
Sun, Earth, magnetic field, weather forecast, space weather, solar activity