Periodic Reporting for period 4 - SolMAG (Unravelling The Structure and Evolution of Solar Magnetic Flux Ropes and Their Magnetosheaths)
Okres sprawozdawczy: 2021-12-01 do 2023-05-31
The SolMAG project aims to derive realistic estimates of the magnetic field in both CME flux ropes and sheaths from Sun to Earth. The project Work Packages (WPs) and their key overall objectives are
WPA “Quantification of Magnetic Structure and Evolution of CME Flux Ropes” analyses CME flux ropes from the point of their formation at the Sun until sampled in-situ. The key objective of WPA is to deliver realistic information on the intrinsic magnetic structure of CMEs at the time of the eruption and its early evolution in the low corona (few first solar radii).
WPB “Comprehensive Characterization of CME Sheaths Regions” studies CME sheaths using a comprehensive in-situ analysis and simulations. Sheaths accrete gradually as CMEs plough supersonically through interplanetary space and physical processes at the shock and at the flux rope leading edge lead to highly irregular and complex structure. The key objectives of WPB are to quantify the occurrence of various plasma waves in CME sheaths and the nature of turbulence.
WPC “Sheath and CME Interactions” studies coupling of turbulent sheaths to Earth’s magnetosheath and one of the most complex processes related to CMEs - the merging of multiple eruptions. The key objectives are to detail how multi-scale CME sheath fluctuations transfer to the Earth’s magnetosheath and use our data-driven simulations and in-situ observations to study CME-CME interactions with flux ropes that have different magnetic structure.
Our comprehensive analysis showed that certain types of plasma waves (mirror mode and ion acoustic waves) are ubiquitous in CME sheaths, in particular close to the CME-driven shock, and they form at the early stages of CME evolution. Our extensive analyses on magnetic fluctuations and turbulent parameters in CME sheaths have revealed that they are likely combinations of processed fluctuations and new fluctuations generated at shock/sheath processes, but that CME-driven shocks are not resetting the turbulence in a similar manner as planetary bow shocks. The results give information of the properties and locations of the most intense fluctuations and how they relate to driver and upstream properties. The importance of small scale structures and slow CMEs having also prominent sheaths was highlighted by our work. Characterising turbulence and plasma waves in sheaths is also highly important for space weather forecasting. Our project studies have also demonstrated turbulent CME-sheaths perturb particularly strongly the Van Allen radiation belts that circle the Earth. High-energy electrons in the belts are a significant threat to satellites orbiting in that region.
The results have been disseminated to scientific community via publications in the leading journals of the field, active participation of conferences and workshops and via social media (Twitter)
Our analysis of sheath regions has provided a wealth of new understanding of magnetic field fluctuations and turbulence in sheath regions. This has also included using new tools in this context, i.e. information theory tools to explore the nature of fluctuations.
The work has also opened several new horizons to continue to research e.g. expand the use of information theory tools for sheath and other solar wind structure studies and integrating lower coronal simulations as standard space weather forecasting tools.