Geoscience Reference
In-Depth Information
Fig. 1.
Atmospheric photochemical pathways for the formation of ozone.
ozone concentrations. Temperature changes affect chemical dynamics
and emission rates of anthropogenic and biogenic ozone precursors. It
has also been established that temperature variations have the largest
impact on peak ozone concentrations and ozone exceedances amongst
all meteorological variables as per Dawson
et al.
7
Therefore, it becomes
important to assess the impact of future global temperature changes and
consequently climate change on air quality decision-making processes.
The south Texas region has experienced several exceedances of the
8-h National Ambient Air Quality Standards (NAAQS) within different
urban and semi-urban regions during the recent years. The region is
characterized by a unique climatology of semi-arid coastal and inland areas
and consists of a number of urban areas classified by the Texas Commission
on Environmental Quality (TCEQ) to be in near non-attainment status of
the 8-h ozone standards. These near non-attainment areas (NNA) have
voluntarily opted to develop appropriate planning processes to continue
to remain in attainment of the federal 8-h ozone standards. The future
modeling scenario considered here was developed as a part of an attainment
demonstration process. The emission estimations from anthropogenic
sources were adjusted to account for such factors as anticipated growth
or decline in population and economy as well as the impact of federal,
state, and regional emission reduction measures.
8
The biogenic emissions
inventory for the 2007 future case was the same as that used in the 1999 base
case, and this was developed in accordance with the USEPA guidelines.
1
