Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 5 6 2005 10.5194/acpd-5-12177-2005 http://www.atmos-chem-phys-discuss.net/5/12177/2005/ http://www.atmos-chem-phys-discuss.net/5/12177/2005/acpd-5-12177-2005.html http://www.atmos-chem-phys-discuss.net/5/12177/2005/acpd-5-12177-2005.pdf 12177 12254 2005-11-24 The North Atlantic Marine Boundary Layer Experiment (NAMBLEX). Overview of the campaign held at Mace Head, Ireland, in summer 2002 D. E. Heard d.e.heard@leeds.ac.uk K. A. Read J. Methven S. Al-Haider W. J. Bloss G. P. Johnson M. J. Pilling P. W. Seakins S. C. Smith R. Sommariva J. C. Stanton T. J. Still B. Brooks G. De Leeuw A. V. Jackson J. B. McQuaid R. Morgan M. H. Smith L. J. Carpenter N. Carslaw J. Hamilton J. R. Hopkins J. D. Lee A. C. Lewis R. M. Purvis D. J. Wevill N. Brough T. Green G. Mills S. A. Penkett J. M. C. Plane A. Saiz-Lopez D. Worton P. S. Monks Z. Fleming A. R. Rickard M. Alfarra J. D. Allan K. Bower H. Coe M. Cubison M. Flynn G. McFiggans M. Gallagher E. G. Norton C. D. O’Dowd J. Shillito D. Topping G. Vaughan P. Williams M. Bitter S. M. Ball R. L. Jones I. M. Povey S. O’Doherty P. G. Simmonds A. Allen R. P. Kinnersley D. C. S. Beddows M. Dall’Osto R. M. Harrison R. J. Donovan M. R. Heal S. G. Jennings C. Noone G. Spain School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK Department of Meteorology, University of Reading, Whiteknights, P.O. Box 217, Reading, Berkshire, RG6 6AH, UK School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK School of Environmental Sciences, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK Department of Chemistry, University of Leicester, Leicester, LE1 7RH, UK School of Earth, Atmospheric and Environmental Sciences (SEAES), University of Manchester, Manchester, M60 1QD, UK University Chemical Laboratory, Cambridge University, Cambridge, UK School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TH, UK School of Geography, Earth and Environmental Sciences, University of Birmingham, Department of Physics, Birmingham, B15 2TT, UK School of Chemistry, University of Edinburgh, West Mains Rd, Edinburgh EH9 3JJ, UK National University of Ireland, Galway, University Road, Galway, Ireland TNO, P.O. Box 96864, 2509 JG, The Hague, The Netherlands Facility for Airborne Atmospheric Measurement (FAAM), Cranfield University, Cranfield, MK43 0AL, UK now at: Aeronomy Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA now at: Department of Environmental Science and Technology, Imperial College of Science, Technology and Medicine, Prince Consort Road, South Kensington, London, SW7 2AZ, UK The North Atlantic Marine Boundary Layer Experiment (NAMBLEX), involving over 50 scientists from 12 institutions, took place at Mace Head, Ireland (53.32° N, 9.90° W), between 23 July and 4 September 2002. A wide range of state-of-the-art instrumentation enabled detailed measurements of the boundary layer structure and atmospheric composition in the gas and aerosol phase to be made, providing one of the most comprehensive in situ studies of the marine boundary layer to date. This overview paper describes the aims of the NAMBLEX project in the context of previous field campaigns in the Marine Boundary Layer (MBL), the overall layout of the site, a summary of the instrumentation deployed, the temporal coverage of the measurement data, and the numerical models used to interpret the field data. Measurements of some trace species were made for the first time during the campaign, which was characterised by predominantly clean air of marine origin, but more polluted air with higher levels of NO_x originating from continental regions was also experienced. This paper provides a summary of the meteorological measurements and Planetary Boundary Layer (PBL) structure measurements, presents time series of some of the longer-lived trace species (O₃, CO, H₂, DMS, CH₄, NMHC, NO_x, NO_y, PAN) and summarises measurements of other species that are described in more detail in other papers within this special issue, namely oxygenated VOCs, HCHO, peroxides, organo-halogenated species, a range of shorter lived halogen species (I₂, OIO, IO, BrO), NO₃ radicals, photolysis frequencies, the free radicals OH, HO₂ and (HO₂+ΣRO₂), as well as a summary of the aerosol measurements. NAMBLEX was supported by measurements made in the vicinity of Mace Head using the NERC Dornier-228 aircraft. Using ECMWF wind-fields, calculations were made of the air-mass trajectories arriving at Mace Head during NAMBLEX, and were analysed together with both meteorological and trace-gas measurements. In this paper a chemical climatology is presented to interpret the distribution of air-mass origins and emission sources, and to provide a convenient framework of air-mass classification that is used by other papers in this issue for the interpretation of observed variability in levels of trace gases and aerosols.