Constraining natural contributions to tropospheric ozone production over Australia and selected areas of the Southern Ocean

• Main Author: Greenslade, Jesse
• Format: Text
• Language: unknown
• Published: School of Earth, Atmospheric, and Life Sciences 2019
• Subjects: isoprene modelling ozone VOC troposphere; Southern Ocean
• Online Access: https://ro.uow.edu.au/theses1/744; https://ro.uow.edu.au/cgi/viewcontent.cgi?article=1744&context=theses1

Ozone in the troposphere is a toxic pollutant that causes respiratory and agricultural damage. The two main sources of tropospheric ozone are chemical production, and transport from the stratosphere. Australia lacks the extensive in-situ measurement sites (or network) required to fully attribute ozone concentrations to these different sources within either regional or urban areas. The primary source is chemical production, which can occur following biogenic emissions of volatile organic compounds (VOCs) when they mix with polluted urban air. Most tropospheric ozone is formed through chemical reactions involving nitrogen oxides, the hydroxyl radical, and VOCs. Most emitted VOCs are of biogenic origin, and the primary biogenic VOC emitted to the atmosphere from land is isoprene; however, estimates of isoprene emission rates are highly uncertain. The second most important source of tropospheric ozone is the stratosphere, which occasionally mixes into the troposphere bringing ozone-rich air masses down towards the Earth’s surface. Transport of ozone from the stratosphere is uncertain, and difficult to measure. These uncertainties affect atmospheric chemistry models, reducing confidence in modelled atmospheric processes such as radiative forcing and air quality forecasting.