The ALE/GAGE site at Cape Meares, Oregon, U.S.A., was operated under the supervision of R.A. Rasmussen and A.J. Crawford of the Oregon Graduate Institute of Science and Technology. The site is located on the Pacific coast of Oregon, immediately overlooking the ocean ~30 m above mean sea level. The site initially appeared to receive largely unpolluted Pacific air, but pollution episodes increased in more recent years. Measurements for CFC-11 began as part of ALE in December 1979. Due to start-up problems, reliable measurements for N2O began in March 1980 and for CFC-12 in November 1980. These measurements continued as part of ALE through July 1984 and as part of GAGE from September 1983 through June 1989.
The monthly mean mixing ratio of CFC-11 increased from 169.4 parts per trillion (ppt) in December 1979 to 253.9 ppt in June 1989. Cunnold et al. (1994) reported that the average rate of increase of CFC-11 was 8.8±0.1 ppt/year from July 1978 to June 1988. The mixing ratio of CFC-12 increased from 326.2 ppt in November 1980 to 481.8 ppt in June 1989. For the period July 1978 to June 1988, Cunnold et al. (1994) determined that the average rate of increase of CFC-12 was 16.7±0.2 ppt/year. For both CFC-11 and CFC-12, the trends are highly significant (P < 0.0001).
The time series of the monthly mean mixing ratios of N2O shows little evidence of an upward trend until about mid-1981, after which the mixing ratio begins to increase in a generally linear fashion. During 1980-89, the monthly values show a highly significant (P < 0.0001) trend. The monthly mixing ratio increased from 301.1 parts per billion (ppb) in March 1980 to a high of 309.1 ppb in December 1988 and then dropped slightly to 307.2 ppb in June 1989. For 1980-88, Prinn et al. (1990) calculated that the mixing ratio of N2O increased by an average of 0.94±0.07 ppb/year. No significant periodic oscillation is evident. Throughout the period of record, the daily N2O variability is generally larger than at equatorial and Southern Hemisphere sites.
Cape
Meares Mixing Ratios Graph
Cape
Meares Mixing Ratios Table
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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