The tropospheric 14CO2 level in mid-latitudes of the Northern Hemisphere (1959-2003)

A comprehensive tropospheric (CO2)-C-14 data set of quasi-continuous observations covering the time span from 1959 to 2003 is presented. Samples were collected at 3 European mountain sites at height levels of 1205 m (Schauinsiand), 1800 m (Vermunt), and 3450 m. as] (Jungfraujoch), and analyzed in the Heidelberg Radiocarbon Laboratory. The data set from Jungfraujoch (1986-2003) is considered to represent the free tropospheric background level at mid-latitudes of the Northern Hemisphere, as it compares well with recent (yet unpublished) measurements made at the marine baseline station Mace Head (west coast of Ireland). The Vermunt and Schauinsland records are significantly influenced by regional European fossil fuel CO2 emissions. The respective Delta(CO2)-C-14 depletions, on an annual mean basis, are, however, only 5 parts per thousand less than at Jungfraujoch. Vermunt and Schauinsland both represent the mean continental European troposphere.