The Effect of Deep Convection on Ozone Levels in Southeast Pennsylvania

Like many variable gases, ozone concentration fluctuates throughout each layer of the atmosphere. In particular, ground-level ozone has been known to spike prior to and during deep convection. A more cohesive understanding of the spread of ozone pollution can contribute to understanding and potentially mitigating its effects. In this project, the general patterns associated with the variations in ozone levels during the life cycle of thunderstorms in southeast Pennsylvania are analyzed. Data was collected from Advanced Pollution Instrumentation Model 400A Ozone Analyzer, NOAA HYSPLIT dispersion model, Vaisala AQT400/WXT530 instruments, and the NWS WSR88D weather radar. With these models and measurements, not only are changes in ozone levels detected, but also a general location of the air source prior to the event is identified. After considering the data, there were clear correlations among the outflow boundary, onset of rain, and rising ozone levels. Certain storms caused a secondary peak in ozone levels presumably produced by lightning. Evaluation of data explores the differences in storm footprint on pollutant spread and concentration levels. Predicted CAPE values at the time of the event were noted, with southeast Pennsylvania storms having generally low values, but the correlation with ozone concentration were weak and introduced ambiguities that clouded the interpretation. Higher ozone concentrations were often found to be correlated with the approach of the gust front or outflow boundary from deep convection events. In other specific events, ozone level spikes occurred after the onset of rain. However, variations in ozone concentration associated with weak deep convection were often indistinguishable from that seen in diurnal cycles. These preliminary results support the correlation between the outflow of deep convection and ground-level ozone pollution trends.