Vertical Ozone Distribution in the Lower Troposphere Near an Urban Pollution Complex

Abstract

Balloon-borne chemiluminescent ozonesondes frequently reveal high ozone amounts in the lowest kilometer over Point Mugu, Calif. The most severe cases, at least, are presumably associated with influx of smoggy pollution from the nearby Los Angeles Basin. Surprisingly, the soundings show a pronounced tendency for maximum ozone to occur above the base of the low-level temperature inversion. A possible explanation might involve lifting of Los Angeles pollutant into the inversion by convection and orography, followed by modification enroute to Point Mugu by differential erosion and differential advection. From the persistence of observed ozone maxima in the soundings, the semipermanent temperature inversion over coastal southern California appears to be an effective reservoir for atmospheric ozone. It seems likely that ozone stored therein can at times reach the surface and contribute to localized pollution.