Map of vertical component of vorticity (∇×V_h, ⊥)⋅e_z (orange-to-purple color scale, saturated at ±10⁻⁴ s⁻¹) near the negative footpoints of the main FR (pink dots) and the intertwined FR (black dots) within the western sunspot (see Fig. 1) during the formation processes of the FRs on 21 April 2013 at 19:00 UT. The blue and red contours correspond to the photospheric B_z of ±100 Mx cm⁻² (blue for negative). The black dashed curve encloses a persistent patch of positive vorticity that encloses the FR footpoints. An animated version of this figure is available online.