The Dependence of C IV Broad Absorption Line Properties on Accompanying
  Si IV and Al III Absorption: Relating Quasar-Wind Ionization Levels,
  Kinematics, and Column Densities
  We consider how the profile and multi-year variability properties of a large
sample of C IV Broad Absorption Line (BAL) troughs change when BALs from Si IV
and/or Al III are present at corresponding velocities, indicating that the
line-of-sight intercepts at least some lower ionization gas. We derive a number
of observational results for C IV BALs separated according to the presence or
absence of accompanying lower ionization transitions, including measurements of
composite profile shapes, equivalent width (EW), characteristic velocities,
composite variation profiles, and EW variability. We also measure the
correlations between EW and fractional-EW variability for C IV, Si IV, and Al
III. Our measurements reveal the basic correlated changes between ionization
level, kinematics, and column density expected in accretion-disk wind models;
e.g., lines-of-sight including lower ionization material generally show deeper
and broader C IV troughs that have smaller minimum velocities and that are less
variable. Many C IV BALs with no accompanying Si IV or Al III BALs may have
only mild or no saturation.
