Dry deposition of ozone is an important sink of ozone in near‐surface air. When dry deposition occurs through plant stomata, ozone can injure the plant, altering water and carbon cycling and reducing crop yields. Quantifying both stomatal and nonstomatal uptake accurately is relevant for understanding ozone's impact on human health as an air pollutant and on climate as a potent short‐lived greenhouse gas and primary control on the removal of several reactive greenhouse gases and air pollutants. Robust ozone dry deposition estimates require knowledge of the relative importance of individual deposition pathways, but spatiotemporal variability in nonstomatal deposition is poorly understood. Here we integrate understanding of ozone deposition processes by synthesizing research from fields such as atmospheric chemistry, ecology, and meteorology. We critically review methods for measurements and modeling, highlighting the empiricism that underpins modeling and thus the interpretation of observations. Our unprecedented synthesis of knowledge on deposition pathways, particularly soil and leaf cuticles, reveals process understanding not yet included in widely used models. If coordinated with short‐term field intensives, laboratory studies, and mechanistic modeling, measurements from a few long‐term sites would bridge the molecular to ecosystem scales necessary to establish the relative importance of individual deposition pathways and the extent to which they vary in space and time. Our recommended approaches seek to close knowledge gaps that currently limit quantifying the impact of ozone dry deposition on air quality, ecosystems, and climate.
Dry deposition is an important sink of tropospheric ozone and influences background and episodic ozone air pollution. Plant canopies remove ozone through uptake by plant stomata, leaf cuticles, and soil. Stomatal uptake of ozone injures vegetation, thereby altering local‐to‐global water and carbon cycling. Observed ozone fluxes are used to inform dry deposition parameterizations in chemical transport models but represent the net influence of several poorly constrained processes. Advancing understanding of the processes controlling dry deposition is key for building predictive ability of the terrestrial ozone sink and plant damage. Here, we constrain the influence of spatial structure in turbulence on ozone dry deposition with large eddy simulation coupled to a multilayer canopy model. We investigate whether organized turbulence separates areas of efficient leaf uptake from areas of high or low ozone mixing ratios. We simulate summertime midday conditions at three homogenous deciduous forests with varying leaf area, soil moisture, and ambient humidity. Sensitivity simulations perturb atmospheric stability, parameters related to ozone dry deposition, how quickly stomata respond to local atmospheric variations, and entrainment of ozone from atmospheric boundary layer growth. Overall, we find a low covariance between ozone and leaf uptake, in part due to counteracting influences from micrometeorological variations on ozone and leaf uptake individually versus the influence of leaf uptake on ozone. The low covariance between ozone and leaf uptake suggests that dry deposition parameterizations and interpretations of ozone flux observations can ignore the influence of organized turbulence on dry deposition.
more » « less- NSF-PAR ID:
- 10445160
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Biogeosciences
- Volume:
- 126
- Issue:
- 6
- ISSN:
- 2169-8953
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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