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

• 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), 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
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; North Atlantic
• Online Access: https://hal.science/hal-00328323; https://hal.science/hal-00328323/document; https://hal.science/hal-00328323/file/acpd-8-7509-2008.pdf; https://doi.org/10.5194/acpd-8-7509-2008

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 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 were 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 O 3 production was evaluated to be -5 ppbv/day leading to low values of O 3 by the time the plume reached Europe. Wet deposition of nitric acid was responsible for an 80% reduction in this O 3 production. If the plume had not encountered precipitation, it would have reached the Europe with O 3 levels up to 80-90 ppbv, and CO levels 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 both O 3 and water vapour showing that CO cannot always be used as a tracer for polluted air masses, especially for plumes transported at low altitudes. The results also show that, in this case, an important increase in the O 3 /CO slope can be attributed to chemical destruction of CO and not to photochemical O 3 production as is often assumed.