35 research outputs found
Bridge-Pier Caisson foundations subjected to normal and thrust faulting:physical experiments versus numerical analysis
Evaluation of rocking and coupling rotational linear stiffness coefficients of adjacent foundations
A single-point modeling approach for the intercomparison and evaluation of ozone dry deposition across chemical transport models (Activity 2 of AQMEII4)
A primary sink of air pollutants and their precursors is dry
deposition. Dry deposition estimates differ across chemical transport
models, yet an understanding of the model spread is incomplete. Here, we
introduce Activity 2 of the Air Quality Model Evaluation International
Initiative Phase 4 (AQMEII4). We examine 18 dry deposition schemes
from regional and global chemical transport models as well as standalone
models used for impact assessments or process understanding. We configure
the schemes as single-point models at eight Northern Hemisphere locations
with observed ozone fluxes. Single-point models are driven by a common set
of site-specific meteorological and environmental conditions. Five of eight
sites have at least 3 years and up to 12 years of ozone fluxes. The
interquartile range across models in multiyear mean ozone deposition
velocities ranges from a factor of 1.2 to 1.9 annually across sites and
tends to be highest during winter compared with summer. No model is within
50 % of observed multiyear averages across all sites and seasons, but some
models perform well for some sites and seasons. For the first time, we
demonstrate how contributions from depositional pathways vary across models.
Models can disagree with respect to relative contributions from the pathways, even when
they predict similar deposition velocities, or agree with respect to the relative
contributions but predict different deposition velocities. Both stomatal and
nonstomatal uptake contribute to the large model spread across sites. Our
findings are the beginning of results from AQMEII4 Activity 2, which brings
scientists who model air quality and dry deposition together with scientists
who measure ozone fluxes to evaluate and improve dry deposition schemes in
the chemical transport models used for research, planning, and regulatory
purposes.</p
A single-point modeling approach for the intercomparison and evaluation of ozone dry deposition across chemical transport models (Activity 2 of AQMEII4)
A primary sink of air pollutants and their precursors is dry deposition. Dry deposition estimates differ across chemical transport models, yet an understanding of the model spread is incomplete. Here, we introduce Activity 2 of the Air Quality Model Evaluation International Initiative Phase 4 (AQMEII4). We examine 18 dry deposition schemes from regional and global chemical transport models as well as standalone models used for impact assessments or process understanding. We configure the schemes as single-point models at eight Northern Hemisphere locations with observed ozone fluxes. Single-point models are driven by a common set of site-specific meteorological and environmental conditions. Five of eight sites have at least 3 years and up to 12 years of ozone fluxes. The interquartile range across models in multiyear mean ozone deposition velocities ranges from a factor of 1.2 to 1.9 annually across sites and tends to be highest during winter compared with summer. No model is within 50 % of observed multiyear averages across all sites and seasons, but some models perform well for some sites and seasons. For the first time, we demonstrate how contributions from depositional pathways vary across models. Models can disagree with respect to relative contributions from the pathways, even when they predict similar deposition velocities, or agree with respect to the relative contributions but predict different deposition velocities. Both stomatal and nonstomatal uptake contribute to the large model spread across sites. Our findings are the beginning of results from AQMEII4 Activity 2, which brings scientists who model air quality and dry deposition together with scientists who measure ozone fluxes to evaluate and improve dry deposition schemes in the chemical transport models used for research, planning, and regulatory purposes