  One can estimate the characteristic magnetic field strength in GMCs by
comparing submillimeter polarimetric observations of these sources with
simulated polarization maps developed using a range of different values for the
assumed field strength. The point of comparison is the degree of order in the
distribution of polarization position angles. In a recent paper by H. Li and
collaborators, such a comparison was carried out using SPARO observations of
two GMCs, and employing simulations by E. Ostriker and collaborators. Here we
reexamine this same question, using the same data set and the same simulations,
but using an approach that differs in several respects. The most important
difference is that we incorporate new, higher angular resolution observations
for one of the clouds, obtained using the Hertz polarimeter. We conclude that
the agreement between observations and simulations is best when the total
magnetic energy (including both uniform and fluctuating field components) is at
least as large as the turbulent kinetic energy.
