Geoscience Reference
In-Depth Information
1. Introduction
The United States Environmental Protection Agency (USEPA) has pres-
cribed the usage of certain types of air quality models to analyze character-
istic ozone episodes and conceptualize ozone abatement strategies for
ozone non-attainment regions in the corresponding State Implementation
Plan (SIP).
1
Each SIP must demonstrate through computer modeling
analyses and estimates that any suggested regulatory proposals will enable
the pollution levels in the region to meet federal air quality standards
in the future. The modeled future case helps determine a hypothetical
future scenario using contemporary meteorology and potential emission
reductions and enables the planners to determine whether the decision-
making processes to reduce emissions are relevant in the context of future
growth and development. However, the current decision-making process
does not account for possible variations in ozone concentrations in the
future due to potential changes in climate. The interaction between air
quality and climate is an interactive process since resultant climate changes
impact global atmospheric chemistry and background levels of air pollutant
concentrations. The Intergovernmental Panel on Climate Change report by
Meehl
,
2
based on results from most recent climatic models, predicts
an average rise of global temperature between 1.4
◦
Cand5.8
◦
Cbythe
year 2100. This significant rise in ambient temperature can impact global
tropospheric chemistry as suggested by Fiore
et al.
,
3
and can therefore
alter the chemical composition of the troposphere and affect both the
surface ozone concentrations and ozone exceedances on regional and urban
scales. Figure 1 highlights the key temperature-dependent photochemistry
involved in the ozone formation.
Meteorological parameters which influence advection, dispersion,
dilution, and rates of atmospheric chemical mechanisms affect air quality
variabilities in most regions. Therefore, it is imperative to account for
climate changes in numerical modeling experiments while developing
emission control policies for the future. Several past studies, such as
those by Seaman
et al.
,
5
have made detailed impact
assessment of meteorological conditions on the surface ozone concentrations
and ozone exceedance events. The study of ozone sensitivity to different
modifications in temperatures employing process modeling and chemical
transport models as described by Baertsch-Ritter
,
4
and Sillman
et al.
et al.
,
6
has revealed that
increases in peak ozone concentrations are directly related to temperature
increases and higher temperatures are usually associated with elevated
et al.
