The monitoring station at Mace Head, Ireland, was opened in January 1987 to serve as a middle-latitude Northern Hemisphere site for GAGE. The site is located on the west coast of Ireland in Galway, ~25 m above mean sea level. It is operated under the supervision of P.G. Simmonds of the University of Bristol. Although generally receiving clean oceanic air, the site is at times (particularly in winter) subject to pollution events originating from sources in eastern Ireland, Great Britain, and continental Europe.
The monthly mean mixing ratio of CFC-11 increased from 238.4 parts per trillion (ppt) in February 1987 to 266.2 ppt in December 1991. During the same period, the mixing ratio of CFC-12 increased from 433.7 to 509.9 ppt. According to Cunnold et al. (1994), the average rate of atmospheric CFC increase at Mace Head from July 1988 to June 1991 was 5.3±0.2 ppt/year for CFC-11 and 13.6±0.4 ppt/year for CFC-12. For both CFC-11 and CFC-12, the trends are highly significant (P < 0.0001).
The mean monthly N2O mixing ratio at Mace Head increased from 305.8 parts per billion (ppb) in January 1987 to 309.6 ppb in December 1991. The values show a highly significant (P < 0.0001) trend during this period, with an average rate of increase of 0.857 ppb/year. No significant periodic oscillation is evident.
CITE AS: Prinn, R.G., R. F. Weiss, F.N. Alyea, D. M. Cunnold, P. J. Frazier,
P.G. Simmonds, A.J. Crawford, R.A. Rasmussen, and R.D. Rosen. 1994. Atmospheric CFC-11
(CCl3F), CFC-12 (CCl2F2), and N2O
from the ALE/GAGE network. In Trends: A Compendium of Data on Global Change..
ORNL/CDIAC-65. Carbon Dioxide Information Analysis Center, Oak Ridge National
Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.
Date created 12/06/96 (jaw)
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