Average evolution of the toroidal and poloidal magnetic field due to flux emergences in the HEARS (Schunker et al. 2016) sample. The blue curves show sin(θ₀)∫_Aϕ R_⊙B_rdA (left panel) and ∫_Aθ R_⊙B_rdA (right panel), where θ₀ is the emergence colatitude. The orange curves show the contributions coming from ∫_T∫_AU_ϕB_rdA dt and ∫_T∫_AU_θB_rdA dt in the left and right panels, respectively. The shaded regions show the respective 1σ error ranges. The error of the total and the error of the contributions from the surface flows are correlated. The difference between the blue and orange curves includes the effect of the contributions from horizontal magnetic flux being carried radially outward by small-scale radial flows. This component is small in the right panel, indicating that the field is east-west aligned before emergence, and only gains a north-south component due to north-south surface motions during the emergence process.