Establishing Lagrangian connections between observations within air masses crossing the Atlantic during the International Consortium for Atmospheric Research on Transport and Transformation experiment

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Methven, J., Arnold, S. R., Stohl, A., Evans, M. J., Avery, M., Law, Kathy S., Lewis, A. C., Monks, P. S., Parrish, D. D., Reeves, C. E., Schlager, H., Atlas, E., Blake, D. R., Coe, H., Crosier, J., Flocke, F. M., Holloway, J. S., Hopkins, J. R., Mcquaid, J., Purvis, R., Rappenglück, B., Singh, H. B., Watson, N. M., Whalley, L. K., Williams, P. I.
• Other Authors: Department of Meteorology Reading, University of Reading (UOR), School of Earth and Environment Leeds (SEE), University of Leeds, Norwegian Institute for Air Research (NILU), NASA Langley Research Center Hampton (LaRC), 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), Department of Chemistry York, UK, University of York York, UK, Department of Chemistry Leicester, University of Leicester, NOAA Earth System Research Laboratory (ESRL), National Oceanic and Atmospheric Administration (NOAA), School of Environmental Sciences Norwich, University of East Anglia Norwich (UEA), Deutsches Zentrum für Luft- und Raumfahrt Oberpfaffenhofen-Wessling (DLR), Rosenstiel School of Marine and Atmospheric Science (RSMAS), University of Miami Coral Gables, Department of Chemistry Irvine, University of California Irvine (UC Irvine), University of California (UC)-University of California (UC), School of Earth, Atmospheric and Environmental Sciences Manchester (SEAES), University of Manchester Manchester, Atmospheric Chemistry Division Boulder, National Center for Atmospheric Research Boulder (NCAR), Facility for Airborne Atmospheric Measurements ( Cranfield (FAAM), National Centre for Atmospheric Science Leeds (NCAS), Natural Environment Research Council (NERC)-Natural Environment Research Council (NERC), Institut für Meteorologie und Klimaforschung - Atmosphärische Umweltforschung (IMK-IFU), Karlsruher Institut für Technologie (KIT), NASA Ames Research Center (ARC), School of Chemistry Leeds
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2006
• Subjects: [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; North Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-00144993; https://hal.archives-ouvertes.fr/hal-00144993/document; https://hal.archives-ouvertes.fr/hal-00144993/file/Methven_et_al-2006-Journal_of_Geophysical_Research__Atmospheres_%281984-2012%29.pdf; https://doi.org/10.1029/2006JD007540

The ITCT-Lagrangian-2K4 (Intercontinental Transport and Chemical Transformation) experiment was conceived with an aim to quantify the effects of photochemistry and mixing on the transformation of air masses in the free troposphere away from emissions. To this end, attempts were made to intercept and sample air masses several times during their journey across the North Atlantic using four aircraft based in New Hampshire (USA), Faial (Azores) and Creil (France). This article begins by describing forecasts from two Lagrangian models that were used to direct the aircraft into target air masses. A novel technique then identifies Lagrangian matches between flight segments. Two independent searches are conducted: for Lagrangian model matches and for pairs of whole air samples with matching hydrocarbon fingerprints. The information is filtered further by searching for matching hydrocarbon samples that are linked by matching trajectories. The quality of these “coincident matches” is assessed using temperature, humidity and tracer observations. The technique pulls out five clear Lagrangian cases covering a variety of situations and these are examined in detail. The matching trajectories and hydrocarbon fingerprints are shown, and the downwind minus upwind differences in tracers are discussed.