Temporal Variation of Atmospheric Fossil and Modern CO 2 Excess at a Central European Rural Tower Station between 2008 and 2014

• Published in: Radiocarbon Vol. 60; no. 5; pp. 1285 - 1299
• Main Authors: Major, István, Haszpra, László, Rinyu, László, Futó, István, Bihari, Árpád, Hammer, Samuel, Jull, A J Timothy, Molnár, Mihály
• Format: Journal Article
• Language: English
• Published: 01.10.2018
• ISSN: 0033-8222; 1945-5755
• DOI: 10.1017/RDC.2018.79

Abstract In 2008, the atmospheric CO 2 measurements at the Hegyhátsál rural tower station were extended further by 14 CO 2 air sampling from two elevations (115 and 10 m a.g.l.), in cooperation with HEKAL (ICER). Since then, a complete six-year-long (2008–2014) dataset of atmospheric CO 2 , Δ 14 C, fossil, and modern CO 2 excess (relative to Jungfraujoch) has been assembled and evaluated. Based on our results, the annual mean CO 2 mole fraction rose at both elevations in this period. The annual mean Δ 14 CO 2 values decreased with a similar average annual decline. Based on our comparison, planetary boundary layer height obtained by modeling has a larger influence on the variation of mole fraction of CO 2 (relative to Jungfraujoch), than on its carbon isotopic composition, i.e. the boundary layer rather represents a physical constraint. Fossil fuel CO 2 excess at both elevations can rather be observed in wintertime and mainly due to the increased anthropogenic emission of nearby cities in the region. The mean modern CO 2 excess at both elevations was even larger in winter, but it drastically decreased at 115 m by summer, while it remained at the winter level at 10 m.