Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic
Item
Title (Dublin Core)
Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic
Description (Dublin Core)
The photochemical evolution of an anthropogenic plume from the New-York/Boston region during its transport at low altitudes over the North Atlantic to the European west coast has been studied using a Lagrangian framework. This plume, originally strongly polluted, was sampled by research aircraft just off the North American east coast on 3 successive days, and then 3 days downwind off the west coast of Ireland where another aircraft re-sampled a weakly polluted plume. Changes in trace gas concentrations during transport are reproduced using a photochemical trajectory model including deposition and mixing effects. Chemical and wet deposition processing dominated the evolution of all pollutants in the plume. The mean net photochemical O<sub>3</sub> production is estimated to be −5 ppbv/day leading to low O<sub>3</sub> by the time the plume reached Europe. Model runs with no wet deposition of HNO<sub>3</sub> predicted much lower average net destruction of −1 ppbv/day O<sub>3</sub>, arising from increased levels of NO<sub>x</sub> via photolysis of HNO<sub>3</sub>. This indicates that wet deposition of HNO<sub>3</sub> is indirectly responsible for 80% of the net destruction of ozone during plume transport. If the plume had not encountered precipitation, it would have reached Europe with O<sub>3</sub> concentrations of up to 80 to 90 ppbv and CO between 120 and 140 ppbv. Photochemical destruction also played a more important role than mixing in the evolution of plume CO due to high levels of O<sub>3</sub> and water vapour showing that CO cannot always be used as a tracer for polluted air masses, especially in plumes transported at low altitudes. The results also show that, in this case, an increase in O<sub>3</sub>/CO slopes can be attributed to photochemical destruction of CO and not to photochemical O<sub>3</sub> production as is often assumed.
Creator (Dublin Core)
Real, E.
Law, K. S.
Schlager, H.
Roiger, A.
Huntrieser, H.
Methven, J.
Cain, M.
Holloway, J.
Neuman, J. A.
Ryerson, T.
Flocke, F.
Gouw, J.
Atlas, E.
Donnelly, S.
Parrish, D.
Date (Dublin Core)
2018-01-15
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-8-7737-2008
https://acp.copernicus.org/articles/8/7737/2008/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
