( a) Scatter diagram illustrating the mismatch between the values of α implied by the preprocessed Hinode/SOT–SP boundary data for all points having B _z >0, and the values of α for field lines in the Wh ⁻ model intersecting these same points. For a consistent boundary condition where the α-correspondence relation is satisfied, the values of α on each field line in the Wh ⁻ solution (which are taken from the negative-polarity end of the field line) would match the measured value of α found at the positive-polarity end. ( b) The differential change dΦ/ dα in net flux Φ integrated over all points having α values greater than the abscissa. The unpreprocessed (red) and preprocessed (black) boundary data for AR 10953 are both shown. Data for which the α-correspondence relation holds have dΦ/ dα = 0.