title: Impact of Enhanced Ozone Deposition and Halogen Chemistry on Tropospheric Ozone over the Northern Hemisphere.
abstract: Fate of ozone in marine environments has been receiving increased attention due to the tightening of ambient air quality standards. The role of deposition and halogen chemistry is examined through incorporation of an enhanced ozone deposition algorithm and inclusion of halogen chemistry in a comprehensive atmospheric modeling system. The enhanced ozone deposition treatment accounts for the interaction of iodide in seawater with ozone and increases deposition velocities by 1 order of magnitude. Halogen chemistry includes detailed chemical reactions of organic and inorganic bromine and iodine species. Two different simulations are completed with the halogen chemistry: without and with photochemical reactions of higher iodine oxides. Enhanced deposition reduces mean summer-time surface ozone by ∼3% over marine regions in the Northern Hemisphere. Halogen chemistry without the photochemical reactions of higher iodine oxides reduces surface ozone by ∼15% whereas simulations with the photochemical reactions of higher iodine oxides indicate ozone reductions of ∼48%. The model without these processes overpredicts ozone compared to observations whereas the inclusion of these processes improves predictions. The inclusion of photochemical reactions for higher iodine oxides leads to ozone predictions that are lower than observations, underscoring the need for further refinement of the halogen emissions and chemistry scheme in the model.
authors.affiliation: †National Exposure Research Laboratory, Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States.
authors.forename: Golam
authors.initials: G
authors.lastname: Sarwar
authors.affiliation: †National Exposure Research Laboratory, Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States.
authors.forename: Brett
authors.initials: B
authors.lastname: Gantt
authors.affiliation: †National Exposure Research Laboratory, Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States.
authors.forename: Donna
authors.initials: D
authors.lastname: Schwede
authors.affiliation: †National Exposure Research Laboratory, Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States.
authors.forename: Kristen
authors.initials: K
authors.lastname: Foley
authors.affiliation: †National Exposure Research Laboratory, Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States.
authors.forename: Rohit
authors.initials: R
authors.lastname: Mathur
authors.affiliation: ‡Atmospheric Chemistry and Climate Group, Institute of Physical Chemistry Rocasolano, CSIC, Madrid 28006, Spain.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Saiz-Lopez
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D001272:Atmosphere / Q000737:chemistry*; D006219:Halogens / Q000737:chemistry*; D007700:Kinetics; D008962:Models, Theoretical; D010126:Ozone / Q000032:analysis*; D012621:Seasons; D013997:Time Factors
chemical_list: D000393:Air Pollutants; D006219:Halogens; D010126:Ozone