Analytical and numerical modelling of coronal mass ejections to understand their space weather impact

Coronal mass ejections (CMEs), the most violent eruptive phenomena occurring in the heliosphere, are recognized as one of the major sources for space weather disturbances. CMEs erupt in the form of gigantic clouds of magnetized plasma from the Sun and can reach Earth within several hours to days. If the magnetic field inside an Earth-directed CME or its associated sheath region has a southward-directed north-south magnetic field component (Bz), then it interacts effectively with the Earth’s magnetosphere, leading to severe geomagnetic storms. Therefore, it is crucial to predict the strength and direction of Bz inside Earth-impacting interplanetary CMEs (ICMEs) in order to forecast their geo-effectiveness. Since the magnetic field of solar eruptions cannot reliably be measured via remote means, and direct continuous measurements of the Earth impacting solar transients are routinely available only very close to our planet, modelling of CME magnetic properties is paramount. In this talk, I will present both analytical and global MHD approaches to predict the CME properties at 1 au, which could prove to be an operation space weather forecasting tool to predict the geo-effectiveness of CMEs. This talk will also showcase the utilisation of multi-wavelength remote-sensing observations as well as multi-spacecraft in-situ observations at different heliocentric distances to constrain the space weather forecasting models. I will also highlight the results based on assessing the performance of different flux-rope models in global MHD simulations to investigate the space weather impact of CMEs.