Nitrogen (N) deposition in the western United States is most severe near major urban areas or downwind of agricultural regions, particularly in areas where confined animal feeding operations such as dairies or feedlots are located. Nitrogen saturated ecosystems are predominantly found in hotspots located within 60 km of urban or agricultural emissions source areas, where N deposition inputs are...

High ground-level ozone concentrations are typical of Mediterranean climates. Plant exposure to this oxidant is known to reduce carbon assimilation. Ozone damage has been traditionally measured through manipulative experiments that do not consider long-term exposure and propagate large uncertainty by up-scaling leaf-level observations to ecosystem-level interpretations. We analyzed long-term co...

A global three-dimensional Lagrangian chemistry-transport model STOCHEM is used to describe the European regional acid deposition and ozone air quality impacts along the Atlantic Ocean seaboard of Europe, from the SO2, NOx, VOCs and CO emissions from international shipping under conditions appropriate to the year 2000. Model-derived total sulfur deposition from international shipping reaches ov...

What are the largest uncertainties in modelling ozone in the troposphere, and how do they affect the calculated ozone budget? Published chemistry-transport model studies of tropospheric ozone differ significantly in their conclusions regarding the importance of the key processes controlling the ozone budget: influx from the stratosphere, chemical processing and surface deposition. This study su...

Anthropogenic land use change (LUC) since preindustrial (1850) has altered the vegetation distribution and density around the world. We use a global model (GEOSChem) to assess the attendant changes in surface air quality and the direct radiative forcing (DRF). We focus our analysis on secondary particulate matter and tropospheric ozone formation. The general trend of expansion of managed ecosys...

[1] Continuous surface-layer ozone flux measurements over the polar, year-round snowpack at Summit, Greenland, resulted in deposition velocities (vd) that were smaller than most previous assumptions and model inputs. Substantial seasonal differences were seen in the ozone vd behavior. Spring, daytime ozone vd values showed low variability and were consistently 0.01 cm s . During summer, ozone f...

Urban ozone concentrations are determined by the balance between ozone destruction, chemical production and supply through advection and turbulent down-mixing from higher levels. At high latitudes, low levels of solar insolation and high horizontal advection speeds reduce photochemical production and the spatial ozone concentration patterns are largely determined by the reaction of ozone with n...

This paper presents an analysis of ozone deposition to a Scots pine forest based on a 1D multi-layer chemical transport model. The study includes an implementation of a resistance scheme for ozone deposition into an existing model, simulations for a one-month period and comparisons with measurement data. The results highlight the importance of non-stomatal sinks, both within the forest canopy a...