Overview of Results of Analysis of Data from the South-Central Coast Cooperative Aerometric Monitoring Program (SCCCAMP 1985)

Abstract

The subject of this paper is an overview of the data analysis collected during the comprehensive five-week South-Central Coast Cooperative Air Monitoring Program (SCCCAMP 1985) in California during September and October 1985. The various data analyses have been designed to develop a better understanding of the atmospheric processes that cause elevated ozone concentrations in the region, which includes Ventura and Santa Barbara counties. The data analyses lead to the conclusion that the ozone episodes observed during the field study are typical of those occurring during the past several years and are most strongly correlated with clear skies, high temperatures (i.e., warm high pressure), and with pressure gradients that would imply an easterly component to the wind flow. These episodes are also marked by mixing depths of 100 m or less over the water and by low mixing depths (i.e., a few hundred meters) over the coastal plains. While it is clear that much of the local ozone is caused by local sources, it is also evident that during many ozone episodes, ozone and its precursors are advected into the region from sources to the east, in the vicinity of Los Angeles. Observed ozone and wind patterns suggest that this advection sometimes takes place at elevations of a few hundred meters through inland valleys and along the coast, and sometimes it takes place in a shallow layer near the surface over the coastal ocean. Because of the presence of time-varying sea breezes and mesoscale eddies, it is possible for recirculation of pollutants to occur, as verified by tracer experiments conducted during the field study.