Sensitivity analysis of O3 formation to its precursors-Multifractal approach

Abstract

Abstract: As a secondary pollutant with strong oxidation, surface O3 is harmful to human health and ecosystem. Accurate identification in the response of ozone formation to its precursors (O3-NOx-NMHCsensitivity) is significant for policy-making of O3 pollution control. Great progress has been made in O3-NOx-NMHC sensitivity analysis based on model-based methods in previous studies. However, large uncertainties from meteorological factors, emission inventory and photochemical mechanism may lead to the deviation between the simulation results and the observations. Properties of nonlinear coupling detrended fluctuation analysis (CDFA) is the ability to reveal the coupling correlations between O3 and its precursors at different time scales, helping us to quantity the contribution degree of NOx and NMHC to O3 formation in our previous work. Here, we further set up a new index to determine directly the O3-NOx-NMHC sensitivity based on CDFA method, and its availability is test by the comparative analysis of classic Empirical Kinetic Modeling Approach (EKMA). Based on this new evaluation index, seasonal change, time dependence and diurnal variation of O3-NOx-NMHC sensitivity for two traffic sites and two general sites located in the north and south of Taiwan respectively are analyzed. The results confirmed that the new index is able to identify the regional difference in temporal variation of O3-NOx-NMHC sensitivity. Thus, the features of quantification, time-saving and easy-operation make it possible for multifractal methods to become an important potential supplement to the methodology of O3-NOx-NMHC sensitivity analysis in the future.