A five year record of high-frequency in situ measurements of non-methane hydrocarbons at Mace Head, Ireland

Aoife Grant, E. L. Yates, P. G. Simmonds, R. G. Derwent, A. J. Manning, D. Young, D. E. Shallcross, S. O'Doherty

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Abstract

Continuous high-frequency in situ measurements of a range of non-methane hydrocarbons have been made at Mace Head since January 2005. Mace Head is a background Northern Hemispheric site situated on the eastern edge of the Atlantic. Five year measurements (2005-2009) of six C-2-C-5 non-methane hydrocarbons have been separated into baseline Northern Hemispheric and European polluted air masses, among other sectors. Seasonal cycles in baseline Northern Hemispheric air masses and European polluted air masses arriving at Mace Head have been studied. Baseline air masses show a broad summer minima between June and September for shorter lived species, longer lived species show summer minima in July/August. All species displayed a winter maxima in February. European air masses showed baseline elevated mole fractions for all non-methane hydrocarbons. Largest elevations (of up to 360 ppt for ethane maxima) from baseline data were observed in winter maxima, with smaller elevations observed during the summer. Analysis of temporal trends using the Mann-Kendall test showed small (<6% yr(-1)) but statistically significant decreases in the butanes and i-pentane between 2005 and 2009 in European air. No significant trends were found for any species in baseline air.

Original languageEnglish
Pages (from-to)955-964
Number of pages10
JournalAtmospheric Measurement Techniques
Volume4
Issue number5
DOIs
Publication statusPublished - 24 May 2011

Keywords

  • non-methane hydrocarbons
  • Mace Head
  • atmospheric chemistry
  • seasonal cycles
  • volatile organic compounds

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