Lagrangian analysis of low altitude anthropogenic plume processing across the North Atlantic

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Real, Elsa, Law, Kathy S., Schlager, H., Roiger, Anke, Huntrieser, H., Methven, J., Cain, M., Holloway, J., Neuman, J.A., Ryerson, T., Flocke, F., De Gouw, J., Atlas, E., Donnelly, S., Parrish, D.
• Other Authors: Service d'aéronomie (SA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), DLR Institut für Physik der Atmosphäre (IPA), Deutsches Zentrum für Luft- und Raumfahrt Oberpfaffenhofen-Wessling (DLR), Department of Meteorology Reading, University of Reading (UOR), NOAA Earth System Research Laboratory (ESRL), National Oceanic and Atmospheric Administration (NOAA), Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder -National Oceanic and Atmospheric Administration (NOAA), Atmospheric Chemistry Division Boulder, National Center for Atmospheric Research Boulder (NCAR), Rosenstiel School of Marine and Atmospheric Science (RSMAS), University of Miami Coral Gables, Department of Chemistry Hays, Fort Hays State University, PNCA; PATOM; INSU-CNRS; ADEME; IPSL
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: envir; geo; North Atlantic
• Online Access: https://doi.org/10.5194/acp-8-7737-2008; https://hal.archives-ouvertes.fr/hal-00349278/file/acp-8-7737-2008.pdf; https://hal.archives-ouvertes.fr/hal-00349278

International audience 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 O3 production is estimated to be −5 ppbv/day leading to low O3 by the time the plume reached Europe. Model runs with no wet deposition of HNO3 predicted much lower average net destruction of −1 ppbv/day O3, arising from increased levels of NOx via photolysis of HNO3. This indicates that wet deposition of HNO3 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 O3 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 O3 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 O3/CO slopes can be attributed to photochemical destruction of CO and not to photochemical O3 production as is often assumed.