Whitepaper #315 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: space weather applications; basic research. Additional topics: space weather research/operations/research loop; ground-based missions/projects; solar physics.
The Sun’s polar fields have global influence over coronal/heliospheric structure, and are believed to seed activity cycles. However, they are difficult to measure from (near) Earth because (1) they are weak overall, and (2) the viewing angle is large. Full-Stokes spectro-polarimetry for the polar fields is a photon-starved problem that we must address with large-aperture telescopes on the ground.