ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-6-2241-2006 The North Atlantic Marine Boundary Layer Experiment(NAMBLEX). Overview of the campaign held at Mace Head, Ireland, in summer 2002 Heard D. E. 1 Read K. A. 1 Methven J. 2 Al-Haider S. 1 Bloss W. J. 1 Johnson G. P. 1 Pilling M. J. 1 Seakins P. W. 1 Smith S. C. 1 Sommariva R. 1 15 Stanton J. C. 1 Still T. J. 1 Ingham T. 1 Brooks B. 3 De Leeuw G. 13 Jackson A. V. 3 McQuaid J. B. 3 Morgan R. 3 Smith M. H. 3 Carpenter L. J. 4 Carslaw N. 4 Hamilton J. 4 Hopkins J. R. 4 Lee J. D. 4 Lewis A. C. 4 Purvis R. M. 14 Wevill D. J. 4 Brough N. 5 Green T. 5 Mills G. 5 Penkett S. A. 5 Plane J. M. C. 5 Saiz-Lopez A. 5 Worton D. 5 Monks P. S. 6 Fleming Z. 6 16 Rickard A. R. 1 6 Alfarra M. R. 7 17 Allan J. D. 7 Bower K. 7 Coe H. 7 Cubison M. 7 Flynn M. 7 McFiggans G. 7 Gallagher M. 7 Norton E. G. 7 O'Dowd C. D. 12 Shillito J. 7 Topping D. 7 Vaughan G. 7 Williams P. 7 Bitter M. 8 Ball S. M. 8 Jones R. L. 8 Povey I. M. 8 O'Doherty S. 9 Simmonds P. G. 9 Allen A. 10 Kinnersley R. P. 10 Beddows D. C. S. 10 Dall'Osto M. 10 Harrison R. M. 10 Donovan R. J. 11 Heal M. R. 11 Jennings S. G. 12 Noone C. 12 Spain G. 12 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 ofYork, Heslington, York, YO10 5DD, UK School ofEnvironmental Sciences, University of East Anglia, Norwich, Norfolk,NR4 7TJ, UK Department of Chemistry, University ofLeicester, Leicester, LE1 7RH, UK School of Earth,Atmospheric and Environmental Sciences (SEAES), University ofManchester, Manchester, M60 1QD, UK University ChemicalLaboratory, Cambridge University, Cambridge, UK Schoolof Chemistry, University of Bristol, Cantock's Close, Bristol BS81TH, UK School of Geography, Earth and EnvironmentalSciences, Univ. Birmingham, Dept. of Physics,Birmingham, B15 2TT, UK School of Chemistry, Universityof 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 AtmosphericMeasurement (FAAM), Cranfield University, Cranfield, MK43 0AL, UK now at: Aeronomy Laboratory, National Oceanic andAtmospheric Administration, Boulder, CO, USA now at:Depart. Environmental Science and Technology, Imperial Collegeof Science, Technology and Medicine, Prince Consort Road, SouthKensington, London, SW7 2AZ, UK now at: Paul ScherrerInstitute, Villigen, Switzerland 21 06 2006 6 8 2241 2272 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/6/2241/2006/acp-6-2241-2006.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/6/2241/2006/acp-6-2241-2006.pdf

The North Atlantic Marine Boundary Layer Experiment (NAMBLEX), involving over 50 scientists from 12 institutions, took place at Mace Head, Ireland (53.32&deg; N, 9.90&deg; 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<sub>x</sub> 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 (O<sub>3</sub>, CO, H<sub>2</sub>, DMS, CH<sub>4</sub>, NMHC, NO<sub>x</sub>, NO<sub>y</sub>, 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 (I<sub>2</sub>, OIO, IO, BrO), NO<sub>3</sub> radicals, photolysis frequencies, the free radicals OH, HO<sub>2</sub> and (HO<sub>2</sub>+&Sigma; RO<sub>2</sub>), 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 for the duration of the campaign 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.

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