ABSTRACT:
Reevaluating the Carbon Bond-IV Photochemical Mechanism
(Under the Direction of Dr. Harvey E. Jeffries)

The Carbon Bond-IV photochemical mechanism is presented as one of the most
widely used models for simulating tropospheric chemistry. Past mechanistic and
kinetic changes to CB-IV that were never subjected to the USEPA vindication
procedure for regulatory photochemical models are tested through modeling
different UNC smog chamber experiments.  These past changes are officially
documented and vindicated in the first part of this project.  CB-IV_99 is presented
as an updated version of the mechanism and is produced through a critical review
of the relevent literature.  Kinetic and minor mechanistic updates are applied to the
mechanism to make it consistent with the currently best available information.
A new heterogeneous wall mechanism, Auxmech99, is presented as a revised
model of the chemical processes occurring on the chamber walls.  The new
and improved wall model strengthens the smog chamber simulations and allows
for better temporal resolution of the chamber reactivity.  CB-IV_99 is vindicated
through modeling the UNC outdoor smog chambers and the UCR-ITC.
Quantitative and qualitative analyses are presented on the performance of the new
mechanism and its predictions are compared to those of two older versions of
CB-IV.  CB-IV_99 exhibits extremely good performance in modeling a wide range
of experiments in multiple smog chambers.  The new mechanism is recommended
for future applications of regulatory AQSM's.  Areas for further improvement
are discussed.