Air Quality Forecasting: A Review of Federal Programs and Research Needs Page: 15
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Research Needs
Nitrogen oxide and VOC emissions continue to react with ozone at night, leading to
additional reactions involving the nitrate radical. These processes can significantly affect
the reactivity and concentration of the pollutant mix that populates the atmosphere during
the next diurnal cycle. Thus, the accurate prediction of tomorrow's air quality requires a
better understanding the chemistry and transport in the nighttime atmosphere.
Heterogeneous processes: Aerosols participate in a variety of chemical and physical
processes in the troposphere. On a regional scale, these processes are associated with
regional air quality as related to visibility and the effects of fine particles on human
health. In this regard, there is a natural synergism between pollutants like ozone and
sulfur dioxide and fine particles. A basic scientific understanding of the chemistry and
physics of the atmosphere is prerequisite for an effective predictive capability and that
the concentrations of pollutants in the atmosphere are often co-dependent because of
interacting chemical reactions.
With this in mind, new research is needed to elucidate:
* how chemical processing on aerosols influences ozone formation
* how the atmospheric oxidation leading to ozone formation leads to aerosol formation
* how atmospheric chemistry influences the growth and chemical composition of
aerosols.
Emissions: Day-to-day changes in emission rates need to be taken into account to
accurately forecast air quality. The potential effects of changes in temperature include
increased biogenic emissions of VOC, increased VOC emissions from motor vehicles,
and increased nitrogen oxides emissions due to increased power demands. Variations in
activity levels at major industrial facilities will also impact air quality. Research is needed
to develop methods to adjust seasonal emission inventories to reflect the probable
emission levels during the forecast period.
3.3 Evaluating / Improving Models
The models used for forecasting air quality can be divided into two broad categories, 1)
parametric models and 2) deterministic models. Regardless of the form of the model it is
important to evaluate model performance so that there is some way to quantify forecast
reliability and identify areas for improvement. The wide variety of approaches and the
form of the forecast produced in current forecast models make it very difficult to
objectively and quantitatively compare different techniques. Also, the factors that control
pollution levels vary from one region to another and mean that a model/technique that
works well in one region may not perform well in another.
In the case of statistical models, a systematic evaluation of the various techniques and
their relative performance would provide a useful guide for areas that are considering
developing a forecast capability.June 2001 15
15
June 2001
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National Science and Technology Council (U.S.). Air Quality Research Subcommittee. Air Quality Forecasting: A Review of Federal Programs and Research Needs, text, June 2001; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc25969/m1/19/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; .