Seminar

Abstract

Tropospheric ozone is a secondary air pollutant of concern for its adverse affects on human health and agricultural crops, as well as its climate impact. Formed primarily from photochemical reactions involving nitrogen oxides (NOx), non-methane volatile organic compounds (NMVOCs), and carbon monoxide (CO), emission control measures have targeted significant emission sources of these compounds for reduction. While reductions of these ozone precursors are generally observed across Europe over the past one to two decades, trends in ground-level ozone have not followed the same trajectory. Trends are extracted over urban, suburban, and rural sites across Europe for ozone and nitrogen dioxide and the relationships explored. While long-term records of NMVOCs are sparse, data from London sites are included and allow for an evaluation of how the atmospheric reactivity regime has changed over the past decade. Model results based on and used in conjunction with the observed trends are used to yield insight into the reasons for the lack of decrease in surface ozone. The talk goes onto further explore the basis for the reactivity change and measures that could be applied to monitor from aircraft and reduce urban air pollution for nitrogen oxides. The exploration of reactivity changes finished with new data on the emergent VOC source of fracking from direct emissions from shales.