Development of an Analytical Technique to Relate Upper Air Meteorological Variables to High Ozone Occurrences in California From 1980 to 1998

The influence of synoptic high pressure and warm temperatures aloft plays a large role in forming high ozone concentrations in the western U.S. Since meteorological data and ozone data have been collected, the trends of episodic ozone concentrations are highly correlated to the presence of large scale upper air ridges with warm temperatures aloft that aid in subsiding air and a shallow mixing layer.

The goal of the paper is to examine the trends of two key upper air variables: a) 500 mb heights and b) 850 mb temperatures and the corresponding trends in ozone statistics such as the number of 1-hour state or federal violations and maximum monthly ozone concentrations. Although indicators such as the presence of El-Nino or La-Nina have been used to characterize ozone patterns in California, the upper air meteorological parameters above are available twice daily, year round and are more robust.

The 500 mb height and 850 mb temperature data were grouped into bins, so that incremental impact on high ozone could be determined. Also, the maximum, minimun, and mean values were calculated and used to display the upper air statisitics versus high ozone concentrations.

The upper air data for all of California, Neveda, southern Oregon, and Arizona were collected from 1980 to 1998. Data were quality assured. Thereafter, these data were plotted along with the ozone indicators described before to show the relationship of high ozone occurrences to impacts of upper air meteorological statistics.

Although not included in this abstract, the final goal is to run the CART program with both meteorological, surface and aloft, and air quality precursor data for the major air basins in California and show the meteorological adjustment that must be made to obtain high ozone concentrations. The present work will serve as background and reference for the longer-term project.