Speaker
Description
Understanding how Earth’s magnetosphere responds to large-scale variations in the geomagnetic field is essential for constraining long-term space climate and radiation exposure. While the present-day magnetosphere is well characterized under a dipole-dominated field, its configuration during geomagnetic excursions and reversals (GER) remains poorly understood. We investigate solar wind-magnetosphere interaction under weakened and non-dipolar field conditions using global magnetohydrodynamic (MHD) simulation models. Paleomagnetic field configurations are used to represent excursion-like scenarios with reduced dipole strength and enhanced multipolar contributions. It is observed that under such conditions, magnetosphere becomes significantly
asymmetric and can get strongly compressed. The loss of dipole dominance results in more spatially distributed magnetic reconnection, increasing solar wind energy coupling and driving enhanced variability in magnetospheric dynamics. These structural changes imply reduced shielding efficiency and increased access of energetic particles to near-Earth space, with potential impacts on the radiation environment. This study provides a systematic framework for quantifying magnetospheric response under extreme geomagnetic conditions, improving our understanding of
space climate variability over geological timescales.