Influence of plant ecophysiology on ozone dry deposition: comparing between multiplicative and photosynthesis-based dry deposition schemes and their responses to rising CO<sub>2</sub> level

Abstract

Abstract. Dry deposition is a key process for surface ozone (O3) removal. Stomatal uptake is a major component of O3 dry deposition, which is parameterized differently in current land surface models and chemical transport models. We developed and used a standalone terrestrial biosphere model, driven by a unified set of prescribed meteorology, to evaluate two widely used dry deposition modeling frameworks, Wesely (1989) and Zhang et al. (2003), with different configurations of stomatal resistance: (1) the default multiplicative method in the Wesely scheme (W89) and Zhang et al. (2003) scheme (Z03), (2) the traditional photosynthesis-based Farquhar–Ball–Berry (FBB) stomatal algorithm, and (3) the Medlyn stomatal algorithm (MED) based on optimization theory. We found that using the FBB stomatal approach that captures ecophysiological responses to environmental factors, especially to water stress, can generally improve the simulated dry deposition velocities compared with multiplicative schemes. The MED stomatal approach produces higher stomatal conductance than FBB and is likely to overestimate dry deposition velocities for major vegetation types, but its performance is greatly improved when spatially varying slope parameters based on annual mean precipitation are used. Large discrepancies were also found in stomatal responses to rising CO2 levels from 390 to 550 ppm: the multiplicative stomatal method with an empirical CO2 response function produces reduction (−35 %) in global stomatal conductance on average much larger than that with the photosynthesis-based stomatal method (−14 %–19 %). Our results show the potential biases in O3 sink caused by errors in model structure especially in the Wesely dry deposition scheme and the importance of using photosynthesis-based representation of stomatal resistance in dry deposition schemes under a changing climate and rising CO2 concentration.

A single-point modeling approach for the intercomparison and evaluation of ozone dry deposition across chemical transport models (Activity 2 of AQMEII4)

“…Several papers illustrate challenges in determining which ozone dry deposition parameterization is best given observations compiled from the literature (Wong et al, 2019;Cao et al, 2022;Sun et al, 2022) or comparing seasonal differences for ozone and sulfur dioxide deposition velocities at Borden Forest (Wu et al, 2018). While we agree with these earlier findings with our completer and more diverse testbed, we take the evaluation a step further by pinpointing how different pathways contribute to the spread.…”

Contrasting the Biophysical and Radiative Effects of Rising CO2 Concentrations on Ozone Dry Deposition Fluxes

“…However, it is likely that the elevated LAI in the Northern Hemisphere contributes to the elevated deposition fluxes in the fully coupled simulation. In the physiologically coupled simulation the limited changes in deposition fluxes are consistent with elevated LAI (through CO 2 fertilization) offsetting stomatal closure from increased CO 2 concentrations (e.g., Sun et al., 2021). If model output of individual deposition pathways described previously were included in this simulation campaign, we would be able to diagnose the different competing processes in more detail.…”

Biogenic isoprene emissions, dry deposition velocity, and surface ozone concentration during summer droughts, heatwaves, and normal conditions in southwestern Europe

“…Several studies show that non-stomatal conductance in the Mediterranean counts as much as stomatal conductance in the O 3 sink budget (e.g. Gerosa et al, 2009;Sun et al, 2022). Moreover, non-stomatal conductance also seems to be significantly affected during droughts and heatwaves.…”

“…In contrast to stomatal conductance, droughts and heatwaves should have opposite effects, i.e. an increase in non-stomatal conductance during heatwaves and a decrease during droughts (Wong et al, 2022). However, such changes are not taken into account in the EMEP deposition scheme implemented in CHIMERE.…”

“…Dry deposition velocity in the Mediterranean depends on both stomatal and non-stomatal conductance (Lin et al, 2020;Sun et al, 2022). Stomatal conductance that can be considerably affected under hot and dry conditions depends on several parameters.…”