This investigation is the second of two centering on the parameter α=(∇×Bh)z/Bz=μ0Jz/Bzand its derivation from photospheric vector magnetogram data. While α can be evaluated at every spatial position where the vector B is measured, for many reasons it is useful to determine a single value of α to parameterize the magnetic complexity of an entire active region, here called αAR(see Leka and Skumanich, 1999). As such, the limitations in today's vector magnetograph data, e.g., finite spatial resolution and limited field of view, may influence any final 'αAR' value. We apply three methods of calculating 'αAR' to degraded high-spatial-resolution data and find that in general the discrepancies worsen for decreasing resolution compared to the original. We apply the three methods to sub-regions centered on the constituent sunspots for AR 7815. Two of the sub-regions are shown to have magnetic twist with significant magnitude but opposite sign. We show by mosaicing or otherwise combining separate sunspot observations that a measure of αARcan be calculated which is consistent with a single large field-of-view observation. Still, the αAR≈0 assigned for the entire active region is an average, and does not accurately represent the magnetic morphology of this flux system. To measure the validity of the αARparameterization, we demonstrate that, from each method, a relevant quantity can be calculated which describes the 'goodness of fit' of the resulting αAR. Given the spatial variation of α(x,y) over an active region, it is suggested that such a second parameter be used either to indicate uncertainty in αARor as a criterion for data selection, as appropriate.
