Understanding Long-term Solar Magnetic Activity Using Dynamo Modelling

Mukhopadhyay, Suprabha (2023) Understanding Long-term Solar Magnetic Activity Using Dynamo Modelling. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS disertation of Suprabha Mukhopadhyay (18MS095)) Thesis_18MS095.pdf - Submitted Version Restricted to Repository staff only Download (14MB)

Abstract

Sun is our host, and it provides us with energy to sustain life at an ambient distance from it. However, multiple studies and observations tell us that there are energetic events occurring on the Sun powered by its magnetic field. This activity has an immense impact on the heliospheric environment and can even destroy life and control the terrestrial climate. Hence, it is essential to study the long-term behaviour of Solar activity to know the future of habitability on our planet. Sun acts as a huge plasma laboratory and also helps us infer the habitability of exoplanets. Solar activity encompasses a lot of interesting dynamic activity due to nonlinear Lorentz feedback and random turbulent motions in the Solar convection zone. One paramount feature of Solar activity is the 11-year Solar cycle marked by the generation and annihilation of magnetic fields by the Solar dynamo acting through the Solar interior. Direct observations and reconstructions of long-term Solar activity clearly exhibit variabilities beyond the decadal timescale – often termed ‘Supermodulations’ – the origin of which is hotly debated. Do such persistent modulations originate from purely deterministic chaos or rather stochastic turbulence in the Sun’s interior plays a more vital role here? Based on our multi-millennial dynamo simulations, we conclusively demonstrate that Solar cycles are inherently stochastic in nature, wherein stochastic forcings indispensably result in multiple bands of Supermodulations in Solar activity. The dynamo simulations used have a qualitatively similar behaviour as the reconstructed Solar activity and can be used for future probes for understanding long-term Solar activity.

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