Air Quality Modelling and Forecasting Guidebook for the States of the Gulf Cooperation Council

The current guidebook presents widely used AQ models employing different modelling approaches for atmospheric and AQ processes, over length scales ranging from the microscale (1 km or less) to the global scale (more than 1000 km). To this end, distinctions are made between operational and experimental models, between dispersion, photochemical, and receptor models, between forecasting and assessment models, and between models adopted and models recommended by regulatory agencies such as the US Environmental Protection Agency (US EPA). This guidebook also highlights recommendations made by regulatory agencies concerning AQ models, including how to evaluate them, data input and other important requirements. It is essential to point out that there is no single model that is optimal for use over a wide range of situations. This is, in part, because the complexity of meteorological phenomena requires different modelling approaches, depending on numerous conditions. This implies that AQ model selection is problem-dependent. Ideally, the optimal AQ model for a given situation is the one that most accurately represents atmospheric transport processes, pollutant dispersion, and chemical reactions in the subject domain.