Exploring the relationship between nitrogen dioxide and ground-level ozone by applying the joint multifractal analysis.

High concentrations of ground-level ozone have a negative impact on human health and the environment, especially in urban places. Detailed knowledge on the effects of nitrogen dioxide on the ozone seasonal pattern is convenient to prevent these undesirable effects. Thus, the joint multifractal approach has been used to complete the information provided by descriptive statistics. The joint multifractal spectra were obtained for 10-min [O3] and [NO2] time series, recorded at Córdoba (southern Spain) in 2007, revealing the presence of two main seasonal patterns: autumn-winter and spring-summer. From the study of the joint multifractal spectra, different variability in the high and low [O3] values was found depending on the concentration of NO2 in each season.