Atmospheric CO₂ and δ13C Measurements from 2012 to 2014 at the Environmental Research Station Schneefernerhaus, Germany: Technical Corrections, Temporal Variations and Trajectory Clustering

摘要

This study presents continuous atmospheric CO_(2) and δ~(13)C measurements by wavelength-scanned cavity ring down spectroscopy (Picarro G1101-i) at the high-mountain station Schneefernerhaus, Germany. δ~(13)C values were post-corrected for methane and water spectral interferences using accompanying measurements of CH_(4) and H_(2)O, and CO_(2) in dried air, respectively. The best precision of ±0.2‰ for δ~(13)C and of ±4 ppb for CO_(2) was obtained with an integration time of about 1 hour for δ~(13)C and 2 hours for CO_(2). The seasonality of CO_(2) and δ~(13)C was studied by fitting background curves for a complete 2-year period. Peak-to-peak amplitudes of the averaged seasonal cycle were 15.5 ± 0.15 ppm for CO_(2) and 1.97 ± 0.53‰ for δ~(13)C, respectively. Based on the HYSPLIT Model, air masses were classified into five clusters, with westerly and northeasterly flows being the most and the least frequent, respectively. In the wintertime, northwest and northeast clusters had a higher median level for ΔCO_(2) and a lower median level for Δδ~(13)C (the difference between observed and background concentrations), likely caused by anthropogenic emissions. In the summertime, air masses from the northwest had the lowest ΔCO_(2) and the highest Δδ~(13)C. Potential source contribution functions (PSCFs) were used to identify the potential source and sink areas. In winter, source areas for high CO_(2) mixing ratios (> 75~(th) percentile) were mainly located in northwestern Europe. In summer, areas with high δ~(13)C ratios (> 75~(th) percentile), indicating a carbon sink, were observed in the air from Eastern and Central Poland.