Authors: Soumyaranjan Dash (Institute for Astronomy, University of Hawaii at Manoa; CESSI, IISER Kolkata, India), Dibyendu Nandy (CESSI, DPS, IISER Kolkata, India), Ilya Usoskin (Space Physics and Astronomy Research Unit and Sodankylä Geophysical Observatory, University of Oulu, Finland)

Solar internal magnetic field variations driven by the dynamo mechanism shapes the solar activity over a range of time-scales. Direct sunspot observations that provide insight to such modulations is limited to past few centuries. However reconstructed solar cycle variations inferred from cosmogenic isotopes exist over past thousands of years. Such long-term record of solar activity shows presence of extreme solar activity fluctuation in the past. But the causal link between these fluctuations and the millennia scale solar dynamo activity, consequent coronal magnetic field, solar wind, open flux and cosmic ray flux variations remain puzzling and the lack of direct coronal magnetic field observations further compound this issue. By utilizing a stochastically forced solar dynamo model and potential field source surface extrapolation we perform long-term simulations to demonstrate how solar dynamo generated magnetic fields govern the structure of the solar corona and the state of the heliosphere during grand minima, maxima and regular activity phases. We describe the differences in the large-scale structuring of the coronal magnetic field and simulate how the open flux and cosmic ray modulation potential vary across different solar activity phases. Our study provides the theoretical foundation for interpreting long-term solar cycle variations inferred from cosmogenic isotope based reconstructions and establishes causality between solar internal variations to the forcing of the state of the heliosphere.