  We report on a study of the finite-temperature QCD transition region for
temperatures between 139 and 196 MeV, with a pion mass of 200 MeV and two
space-time volumes: $24^3\times8$ and $32^3\times8$, where the larger volume
varies in linear size between 5.6 fm (at T=139 MeV) and 4.0 fm (at T=195 MeV).
These results are compared with the results of an earlier calculation using the
same action and quark masses but a smaller, $16^3\times8$ volume. The chiral
domain wall fermion formulation with a combined Iwasaki and dislocation
suppressing determinant ratio gauge action are used. This lattice action
accurately reproduces the $\sua$ and $\ua$ symmetries of the continuum. Results
are reported for the chiral condensates, connected and disconnected
susceptibilities and the Dirac eigenvalue spectrum. We find a pseudo-critical
temperature, $T_c$, of approximately 165 MeV consistent with previous results
and strong finite volume dependence below $T_c$. Clear evidence is seen for
$\ua$ symmetry breaking above $T_c$ which is quantitatively explained by the
measured density of near-zero modes in accordance with the dilute instanton gas
approximation.
