Mean and standard deviation (SD) of the Northern hemispheric atmospheric abundance of 14C ‰ from all referenced sources by year as conflated from multiple sources.
References:
[1] Patrick, A.D. & Patrick, B.E., Carbon 14 Decay as a Source of Somatic Point Mutations in Genes Correlated with Cancer Diagnoses, Stable Isotope Foundation, Grants Pass, OR (2017).
[2] Levin, I., B., et. al., Δ14CO2 record from Vermunt. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A. (1994).
[3] US Dept. of Commerce, NOAA, Earth System Research Laboratory, Niwot Ridge, CO US (NWR) C14/C in CO2 Monthly Averages, (2003-2007).
[4] Levin, I., and Kromer, B., The tropospheric Δ14C level in mid-latitudes of the Northern Hemisphere (1959-2003), Radiocarbon 46 (3), (2004).
[5] Hua, Q., and Barbetti, M., Influence of atmospheric circulation on regional 14CO2 differences, J. Geophys. Res. 112, D19102, (2007).
[6] Vay, S. A., et. al., Sources and transport of 14C in CO2 within the Mexico City basin and vicinity, Atmos. Chem. Phys. 9, 4973-4985 (2009).
[7] Levin, I., et. al., Observations and modelling of the global distribution and long-term trend of atmospheric 14CO2, Tellus B 62(1):26-46 (2010).
[8] Graven, H. D., et. al., Observations of radiocarbon in CO2 at La Jolla, California, USA 1992 – 2007: Analysis of the long-term trend, J. Geophys. Res. 117, D02302, (2012).
[9] Levin, I., Kromer, B., and Hammer, S., Atmospheric Δ14CO2 trend in Western European background air from 2000 to 2012, Tellus B 65, 20092 (2013).
[10] Lafranchi, B., et. al., Strong regional atmospheric 14C signature of respired CO2 observed from a tall tower over the mid-western United States: Atmospheric 14C of respired CO2, J. Geophys. Res.: Biogeosciences August 2016, (2016).
Note: ‰ indicates abundance in parts per thousand.