Abstract. Soil moisture and water stress play a pivotal role in regulating stomatal
behaviour of plants; however, in the last decade, the role of water
availability has often been neglected in atmospheric chemistry modelling
studies as well as in integrated risk assessments, despite the fact that
plants remove a large amount of atmospheric compounds from the lower
troposphere through stomata. The main aim of this study is to evaluate, within the chemistry transport
model CHIMERE, the effect of soil water limitation on stomatal conductance
and assess the resulting changes in atmospheric chemistry testing various
hypotheses of water uptake by plants in the rooting zone. Results highlight how dry deposition significantly declines when soil
moisture is used to regulate the stomatal opening, mainly in the semi-arid
environments: in particular, over Europe the amount of ozone removed by dry
deposition in one year without considering any soil water limitation to
stomatal conductance is about 8.5 TgO3, while using a dynamic layer
that ensures that plants maximize the water uptake from soil, we found a
reduction of about 10 % in the amount of ozone removed by dry deposition
(∼ 7.7 TgO3). Although dry deposition occurs from the top of canopy to
ground level, it affects the concentration of gases remaining in the lower
atmosphere, with a significant impact on ozone concentration (up to 4 ppb)
extending from the surface to the upper troposphere (up to 650 hPa). Our results shed light on the importance of improving the parameterizations
of processes occurring at plant level (i.e. from the soil to the canopy) as
they have significant implications for concentration of gases in the lower
troposphere and resulting risk assessments for vegetation or human health
