Development of the Deposition of Ozone for Stomatal Exchange (DO3SE) model

DO₃SE – which is embedded within the EMEP chemistry transfer model (CTM) – has been instrumental in establishing a climate-dependant O₃ flux approach in Europe that was formally adopted by the UNECE/Long Range Transboundary Air Pollution (LRTAP) Convention for the assessment of threats posed by O₃ to ecosystems and human health across the continent. The wide-spread use of DO₃SE requires it to be continuously developed further and evaluated.

One of the main achievements recently has been the launch of the interfaced version of DO₃SE (http://www.sei.org/do3se) so that the model can now be accessed online. Also, to optimise the modelling of the dry deposition of tropospheric ozone (O₃) to terrestrial surfaces and at the same time improve our understanding of how ecosystems (forests, crops and grassland) and human health are impacted by this phytotoxic air pollutant, DO₃SE estimates of seasonal variation in O₃ deposition and flux have been evaluated. This included the development and evaluation of the DO₃SE soil moisture module for the assessment of the effect of soil water stress on stomatal O₃ flux.

In the near future, DO₃SE will be further developed for application to more complex semi-natural communities (a multi-layer, multi-component approach has already been developed), which will help to understand the influence of O₃ on ecosystem services provided by grasslands across the UK.

Related to this, effects of O₃ on productive pastures, forage quality and hence commodities related to livestock farming could be targeted, which together with assessments of future changes in crop productivity under conditions of climate change could identify the potential impacts of O₃ on food security.

Furthermore, it is becoming increasingly important to understand the influence of hemispheric and intra-continental O₃ transport on the air quality and associated impacts to human health and ecosystems in the UK and Europe. Improvements in the estimation of O₃ dry deposition will be crucial to quantify the amount of imported O₃ both from continental Europe as well as intercontinental hemispheric transport that influence UK air quality, and DO₃SE will provide the opportunity to allow these assessments.

Finally, DO₃SE is currently being prepared and promoted for local and regional applications in South Asia and southern Africa, which will eventually enable the quantification of the impacts of a changing chemical and physical atmosphere on large- as well as small-scale farming in these regions.

The development and evaluation of DO₃SE has been funded by the Defra, UK.