ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-8017-2011 European source and sink areas of CO<sub>2</sub> retrieved from Lagrangian transport model interpretation of combined O<sub>2</sub> and CO<sub>2</sub> measurements at the high alpine research station Jungfraujoch Uglietti C. 1 2 Leuenberger M. 1 2 Brunner D. 3 Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstr. 5, 3012 Bern, Switzerland Oeschger Centre for Climate Change Research, Zähringerstr. 25, 3012 Bern, Switzerland Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstr. 129, 8600 Dübendorf, Switzerland 08 08 2011 11 15 8017 8036 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/11/8017/2011/acp-11-8017-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/8017/2011/acp-11-8017-2011.pdf

The University of Bern monitors carbon dioxide (CO<sub>2</sub>) and oxygen (O<sub>2</sub>) at the High Altitude Research Station Jungfraujoch since the year 2000 by means of flasks sampling and since 2005 using a continuous in situ measurement system. This study investigates the transport of CO<sub>2</sub> and O<sub>2</sub> towards Jungfraujoch using backward Lagrangian Particle Dispersion Model (LPDM) simulations and utilizes CO<sub>2</sub> and O<sub>2</sub> signatures to classify air masses. By investigating the simulated transport patterns associated with distinct CO<sub>2</sub> concentrations it is possible to decipher different source and sink areas over Europe. The highest CO<sub>2</sub> concentrations, for example, were observed in winter during pollution episodes when air was transported from Northeastern Europe towards the Alps, or during south Foehn events with rapid uplift of polluted air from Northern Italy, as demonstrated in two case studies. <br><br> To study the importance of air-sea exchange for variations in O<sub>2</sub> concentrations at Jungfraujoch the correlation between CO<sub>2</sub> and APO (Atmospheric Potential Oxygen) deviations from a seasonally varying background was analyzed. Anomalously high APO concentrations were clearly associated with air masses originating from the Atlantic Ocean, whereas low APO concentrations were found in air masses advected either from the east from the Eurasian continent in summer, or from the Eastern Mediterranean in winter. Those air masses with low APO in summer were also strongly depleted in CO<sub>2</sub> suggesting a combination of CO<sub>2</sub> uptake by vegetation and O<sub>2</sub> uptake by dry summer soils. Other subsets of points in the APO-CO<sub>2</sub> scatter plot investigated with respect to air mass origin included CO<sub>2</sub> and APO background values and points with regular APO but anomalous CO<sub>2</sub> concentrations. Background values were associated with free tropospheric air masses with little contact with the boundary layer during the last few days, while high or low CO<sub>2</sub> concentrations reflect the various levels of influence of anthropogenic emissions and the biosphere. The pronounced cycles of CO<sub>2</sub> and O<sub>2</sub> exchanges with the biosphere and the ocean cause clusters of points and lead to a seasonal pattern.

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