Multidimensional and Multiscale Pattern of Western U.S. Ozone.

The multitude of sources and sinks, along with the high reactivity and metastability of ozone make it difficult to attribute ambient ozone concentrations to specific sources. Source attribution over the Western US is particularly complicated by unpredictable forest fires, hemispheric transport from distributed global sources and stratospheric ozone incursions. While advances over the past decades yielded much improved ambient measurements, better emission estimates, detailed mechanistic and statistical and chemical models and statistical techniques, a full reconciliation and ‘closure’ of measured ambient ozone concentrations, with precursor emissions has remained elusive.

In this report, we are applying systematic pattern analysis as an additional tool set for comparing and reconciling emissions, observations and models. A common set of pattern and a pattern language is used to describe atmospheric parameters that are distributed along time, space and parameter dimensions with multiple scales along each dimension. The temporal patterns are at diurnal, weekly, seasonal and secular scales. The weekly and secular-scale pattern is driven mainly by human influences while the diurnal and seasonal pattern are more influenced by nature. The horizontal spatial variation and pattern include plumes, urban domes and regional ‘blobs’ as they occur at micro, meso, synoptic and hemispherical scales. The vertical pattern includes well-mixed layer and ‘bliny’ (pancakes). All atmospheric phenomena are characterized by their respective spatial and temporal pattern.

A pattern catalog along with a consistent pattern description language (1) aids the identification of major drivers of variation; (2) facilitates comprehensive comparison and reconciliation of data and models along multiple dimensions and scales; (3) allows estimation of unusual deviation from standard pattern. Such anomalous pattern along with statistical analyses and chemical transport model results for specific ozone events can be used as evidence and documentation of Exceptional Air Quality Events.