A Quantitative Study of Magnetic Flux Transport on the Sun

A computational model, based on diffusion, differential rotation, and meridional circulation, has been developed to simulate the transport of magnetic flux on the Sun. Using Kitt Peak magnetograms as input, we have determined a best-fit diffusion constant by comparing the computed and observed fields at later times. Our value of 730 ± 250 km 2 /s is consistent with Leighton's (1964) estimate of 770–1540 km 2 /s and is significantly larger than Mosher's (1977) estimate of 200–400 km 2 /s. This suggests that diffusion may be fast enough to account for the observed polar magnetic field reversal without requiring a significant assist from meridional currents.