Observations of AR 11429 on 2012 March 6 23:36 UT derived from the SHARP CEA vector magnetogram. (a) Vertical component of the photospheric magnetic field, B_z(x, y), over the SHARP region. The NLFFF models are constructed over the entire field of view, and subsequent analysis is carried out in the region within the dashed green box. (b) Vertical current density J_z(x, y) at the photosphere in the region represented by the dashed green box in panel (a). The black B_z = 0 contours in both panels indicate the main PILs.