Inter-basin ozone transport issues within N. California

The assessment and quantification of inter-basin ozone transport has been the subject of substantial work in northern California. There are a number of ozone nonattainment areas in the region, and several transport couples between these different areas have been identified. Previous work has utilized both data analysis and modeling approaches to investigate transport, although quantification has proven difficult. The geography and meteorology of California's Central Valley are quite complex and challenging to model, and also complicate the interpretation of data-based analyses. However, the transition from a 1-hour to 8-hour ozone standard has made the assessment of transport even more important for the development of equitable control strategies, since the 8-hour standard is more stringent and transport may represent a more significant burden to downwind districts.

This paper will summarize previous transport assessment work, and the challenges that remain. It will also describe recent efforts by air agencies and industry to coordinate and conduct transport assessment and quantification analyses in northern California. The results of this effort are expected to be used in the design of equitable emission control strategies for the region.