Atmospheric Δ 14 CO 2 trend in Western European background air from 2000 to 2012

TLDR: In this article, long-term measurements of atmospheric Δ 14 CO 2 from two monitoring stations, one in the European Alps (Jungfraujoch, Switzerland) and the other in the Black Forest (Schauinsland, Germany), are presented.

Abstract: Long-term measurements of atmospheric Δ 14 CO 2 from two monitoring stations, one in the European Alps (Jungfraujoch, Switzerland) and the other in the Black Forest (Schauinsland, Germany), are presented. Both records show a steady decrease, changing from about 6‰ per year at the beginning of the century to only 3‰ per year on average in the last 4 yr. A significant seasonal variation of Δ 14 CO 2 is observed at both sites with maxima during late summer and minima in late winter/early spring. While the Δ 14 C maxima are similar at Jungfraujoch and Schauinsland, the minima at Schauinsland are lower by up to 10‰, due to a larger influence from 14 C-free fossil fuel CO 2 emissions in the footprint of the Schauinsland station in winter. Summer mean Δ 14 C values at Schauinsland are considered best suited as input for studies of biospheric carbon cycling in mid-northern latitudes or for dating of organic material of the last half century. Keywords: carbon dioxide, radiocarbon, clean air reference (Published: 18 March 2013) Citation: Tellus B 2013, 65 , 20092, http://dx.doi.org/10.3402/tellusb.v65i0.20092