Terms contributing to the average cE^FE as a function of central emergence latitude and time Panels A and B show the diffusive and advective contributions to cE^FE_θ, and panels C and D show the contributions to cE^FE_ϕ. Here, U′ and B′ are the velocity and magnetic fields without their longitudinal means. Panels E and F show the contributions from U_ϕ′B_r′ and U_θ′B_r′ as well as the total cE^FE_θ and cE^FE_ϕ integrated from one day before emergence (t = −1 day) to one day after emergence (t = 1 day). The shaded regions show the 1σ error range, calculated from the four time-segments used in the analysis. Panel G shows Joy’s law based on the total longitudinal separation (the blue curve from panel E) and the total latitudinal separation (the blue curve from panel F), and Joy’s law based on the separation in latitude due to the latitudinal surface velocity acting on the radial field (the orange curve from panel F). The green line show Joy’s law derived from observations (e.g. Dasi-Espuig et al. 2010).