The effect of intraseasonal variability on ground level ozone in Los Angeles, California from 1980-2011

ABSTRACT

High concentrations of surface ozone have been found to be hazardous to human and ecosystem health. Surface ozone is a byproduct of the reaction between nitrous oxide (NOx) and volatile organic compounds (VOCs) in the presence of ultraviolet solar radiation. The amount of ozone created by these chemical reactions is dependent on several factors, most important among them are the ratio of NOx to VOC and the intensity and duration of ultraviolet solar radiation. A secondary relationship has been confirmed between ground level ozone, temperature, precipitation and humidity. Concentrations of ground level ozone have been found to be highest during the summer months of June to September, although variability within those months has not yet been examined extensively. The purpose of this study is to analyze the intraseasonal variability of ground level ozone in Los Angeles, California. Several recent studies, focusing on global regions with geographic characteristics similar to Los Angeles, have found that surface ozone varies by phase of the leading mode of atmospheric intraseasonal variability, the Madden Julian Oscillation (MJO). However, the ground level ozone in the Los Angeles area has not yet been extensively examined for connections to the MJO. Thus, the objective of this study is two-fold; (1) quantify the intraseasonal variability of surface ozone in Los Angeles, and (2) explain the observed variability in ozone by examining composite anomalies of other atmospheric variables known to be modulated by the MJO. This study uses values of ozone in ppm found in Los Angeles from the data collected in the summer months of 1980-2011. Using these values, results will be presented showing which environmental characteristics have the greatest effect on ground level ozone and whether intraseasonal variability is a prominent factor.