Ozone Concentration Profiles in the Los Angeles Basin A Possible Similarity in the Build-up Mechanism of Inland Surface Ozone in Israel

Abstract

This paper analyzes some measurements of the Southern California Air Quality Study, which collected a comprehensive air quality, meteorological, and emissions database in the Los Angeles Basin. This analysis emphasizes the interaction of the enriched ozone layer existing aloft with the top of the convective boundary layer (CBL) in the early afternoon of warm summer days, leading to downward mixing (fumigation) of the ozone cloud toward the ground. This process was shown to contribute to the high ozone concentrations measured at inland elevated sites. It is suggested that this mechanism also exists in Israel and contributes to the elevated concentrations observed in the summer on the slopes of the Judean Hills. This analogy is based on the similarity between the Los Angeles Basin and central Israel regarding the climate, the local circulation (sea breeze), the orientation of the coast, and the upwind location of ozone precursor sources. The temporal fluctuations of the synoptic configuration persisting over Israel during the summer cause rapid variations in the depth of the CBL inland and its subsequent interaction with an ozone layer aloft.