Air Quality Modeling
7.1 Overview of Air Quality Modeling
7.1.1 Introduction
The atmosphere is an extremely complex reactive system in which numerous physical and chemical processes occur simultaneously. Ambient measurements give us only a snapshot of atmospheric conditions at a particular time and location. Such measurements are often difficult to interpret without a clear conceptual model of atmospheric processes. Moreover measurements alone cannot be used directly by policymakers to establish an effective strategy for solving air quality problems. Mathematical models provide the necessary framework for interactions. A combination of state-of-the-science measurements with state-of-the science models is the best approach for making real progress toward understanding the atmosphere.
Historically, air pollution came to be regarded as a serious problem for certain large cities, but with the advent of the industrial revolution and later coming of the automobile, air quality of most large urban and industrial areas took a nosedive. Air quality problems are growing in complexity and scope, local measurements or local management solutions alone can no longer address many of the questions generally in urban, regional even global air quality studies, such as the following:
What is the contribution of source A (or sources A, B, C, etc) to the concentration of pollutants at site K (or sites K, L, M, N, etc)?
What is the most cost-effective strategy for reducing pollutant concentrations below an air quality standard?
What will be the effect on air quality of increase or the decrease of a specific air pollutant emission?
Where should one place a future source (industrial complex, freeway, etc.) to minimize its environmental impacts?
What will be the air quality tomorrow or the day after? (Does the threat of smog or regional haze exist any more tomorrow? etc)
A model involving descriptions of emission patterns, meteorology, chemical transformations and removal processes is the essential tool for establishing the emission fluxes and ambient concentrations, and so as to provide a link between emission changes from source control measures and resulting changes in airborne concentrations, and finally to asses the air pollution problems and evaluate the alternative control measures and strategies for policy makers.
Before the subject of true air quality modeling is taken up, it is useful to discuss a primitive form of modeling called proportional modeling. Promotional modeling is discussed in Section 7.1.1. This is followed by a discussion of the components of modern air quality modeling. model classifications, and model development. Descriptions of dispersion models and atmospheric reactive models follow in later sections. The air quality model design, simulation and application are then discussed in the final sections using the Models-3 as an example.
Historically, air pollution came to be regarded as a serious problem for certain large cities, but with the advent of the industrial revolution and later coming of the automobile, air quality of most large urban and industrial areas took a nosedive. Air quality problems are growing in complexity and scope, local measurements or local management solutions alone can no longer address many of the questions generally in urban, regional even global air quality studies, such as the following:
What is the contribution of source A (or sources A, B, C, etc) to the concentration of pollutants at site K (or sites K, L, M, N, etc)?
What is the most cost-effective strategy for reducing pollutant concentrations below an air quality standard?
What will be the effect on air quality of increase or the decrease of a specific air pollutant emission?
Where should one place a future source (industrial complex, freeway, etc.) to minimize its environmental impacts?
What will be the air quality tomorrow or the day after? (Does the threat of smog or regional haze exist any more tomorrow? etc)
A model involving descriptions of emission patterns, meteorology, chemical transformations and removal processes is the essential tool for establishing the emission fluxes and ambient concentrations, and so as to provide a link between emission changes from source control measures and resulting changes in airborne concentrations, and finally to asses the air pollution problems and evaluate the alternative control measures and strategies for policy makers.
Before the subject of true air quality modeling is taken up, it is useful to discuss a primitive form of modeling called proportional modeling. Promotional modeling is discussed in Section 7.1.1. This is followed by a discussion of the components of modern air quality modeling. model classifications, and model development. Descriptions of dispersion models and atmospheric reactive models follow in later sections. The air quality model design, simulation and application are then discussed in the final sections using the Models-3 as an example.
