Joint multifractal analysis of the influence of temperature and nitrogen dioxide on tropospheric ozone

The joint partition function approach to multifractal analysis (Meneveau et al., Phys Rev A 41:894–913, 1990) has been widely employed in order to characterize scale relationships between two variables coexisting along a single geometric support. The main contribution of this study was conducting a multifractal analysis for three variables coexisting in the same geometric support, in order to describe the influence across temporal scales of a meteorological and chemistry variable (temperature and NO₂) on tropospheric ozone concentrations. Hourly time series were recorded in the city of Seville (Spain) for summer 2011. Joint multifractal analysis was conducted by considering both the strange attractor formalism and the method of moments. Results confirmed the scale dependence among the studied variables and demonstrated the capability of joint multifractal analysis to completely characterize the scaling behaviour among three variables. Temporal variability in temperature is strongly reflected on ozone concentrations across analyzed temporal scales, but the joint multifractal spectrum for nitrogen dioxide and ozone suggest a lower degree of correlation. A loss of multifractality is found when both high temperatures and nitrogen dioxide concentrations occur. By contrast, greater variability is found in the opposite scenario.