Changes in the temperature sensitivity of surface ozone production: a case-study based on long-term observations in Austria

As the production of ozone in surface air is determined by ambient temperature and by the prevalent chemical regime, a very different temperature dependence of ozone production emerges for NOx and VOC limited regions. In this study we evaluated the temperature sensitivity of ozone production for rural, suburban as well as urban sites in Austria on seasonal basis. The analysis is based on observational data from Austrian monitoring networks for the time period spanning 1990 - 2018. Surface ozone, nitrogen oxides (NOx), daily sums of global radiation and minimum daily temperature are used as covariates in our study. The observed NOx to VOC ratio at individual sites is variable over time due to changes in precursor emissions and/or the variability of meteorological parameters such as mixing layer height. At the site level we relate the temperature sensitivity of ozone production to the daily mean NOx mixing ratio and the daily minimum temperature. This information allows us to determine the impact of past/future temperature changes on surface ozone abundance in the context of reductions of NOx emissions and changing methane backgrounds.