(Invited Speaker) Relating conceptual models of summer high pollution events and mid-latitude cyclogenesis for air quality forecasting

To investigate the causal relations of air pollution episodes and to assess effectiveness of the emission controls, conceptual models of local and regional meteorological and emissions conditions have been utilized widely. Building similar conceptual models of the pollution events for the Conterminous US (CONUS) domain would be particularly useful to understand the inter-relation of synoptic and regional meteorology to air pollution events as well as to improve chemical weather forecasting capability for the nation. First, a few conceptual models of local/regional air quality episodes are surveyed. Second, an attempt is made to build relations between the conceptual models of air quality episodes with the mid-latitude cyclogenesis and frontal systems associated with the movement of continental and subtropical air masses. Occurrence of a particular air pollution episode is shown to be directly related to the evolutionary change in the relative locations of emission sources to the weather conditions. Transport of pollutants and their precursors, photochemical production of secondary pollutants, and wet/dry removal processes are explained with the general meteorological conditions associated with the mid-latitude cyclogenesis. Effects of the frequent passage of frontal systems on the chemical species budgets in the air quality models are studied for a summer month. Proven conceptual models can be used to identify causes of the model forecast biases and to reveal deficiencies in the science process algorithms and model inputs. Also they can be extended to relate future air quality to the climate change effects such as the altered frequency, seasonal distribution, and intensity of synoptic patterns that favor pollution episodes at different regions.