[Observational study of ozone production efficiency at the Shangdianzi regional background station]

Ambient O3, NOx, NOy, and CO were measured at the Shangdianzi regional background station from 26 March to 9 October 2008, and VOCs samples were taken and analyzed. This paper uses the data to obtain the ozone production efficiency (OPE) at Shangdianzi and studies the relationship of OPE with NO, and VOCs. In addition, the potential impact from the dry deposition of NOx oxidation products on the calculated OPE was estimated and tentatively corrected. Based on this study, the daily OPE varied in the range of 0.2-21.1, with an average of 4.9 +/- 3.6. An overall OPE average of 4.3 +/- 1.5 can be obtained. The dependence of OPE on the NO, concentration can be described using an empirical parabolic function. If the concentration of NOx is lower than 14 x 10(-9), OPE increases with NO,; while if the concentration of NOx is higher than 14 x 10(-9), OPE decreases with NOx. The correlation analysis indicates that the concentrations of aromatics and OVOCs are positively correlated to OPE. Dry deposition of HNO3 and other NO, oxidation products may significantly impact the calculated OPE values, leading to overestimate. It is possible to correct such overestimate using the NOy/CO ratios obtained at an urban site and at Shangdianzi. However, this correction is less rigorous and the corrected OPE data remain to be validated. The uncorrected data can be viewed as the upper limit of the real OPE.