2024-06-162024-06-162015https://doi.org/10.60810/openumwelt-1369https://openumwelt.de/handle/123456789/7769In this study, observed episodes of CO2 concentrations at eight Northern Hemisphere (NH) sites from 1993 to 2012 were analyzed. Five-day back trajectories were calculated for a potential source contribution function (PSCF) analysis. A normalized weight factor related to the occurrence of the episodes was applied to derive more reasonable CO2 elevations and sequestrations. Weighted elevated (?CO2(W_E)) and sequestered (?CO2(W_S)) CO2 episodes had large spatial discrepancies due to the differentiation of strength and patterns of CO2 emissions/sinks in different regions. The most significant enhancement in CO2 episodes was observed at Asian sites: ?CO2(W_E) increased by approximately 56% at an annual rate of ~4% yr-1 from 1995 to 2010 at Waliguan (WLG) and by approximately 39% (~3% yr-1) from 1997 to 2012 at Yonagunijima (YON). According to the PSCF analysis, these increases are largely attributed to the rapid increase in emissions in China. However, ?CO2(W_S) was also enhanced by 34.4% with a growth rate of 2.3% yr-1 at WLG from 1995 to 2010 and ~26.2% (1.7% yr-1) at YON from 1997 to 2012. Both ?CO2(W_E) and ?CO2(W_S) showed decreasing or relatively flat trends at Monte Cimone and Schauinsland, indicating reductions in emissions and sinks in central Europe. The different intensities/trends in emissions and sinks observed at different sites in the NH show that estimating future CO2 levels is a complex problem. Atmospheric inverse and process-based ecosystem models should use more regional input data at high temporal and spatial resolutions for future carbon flux estimations.<BR>Quelle: www.sciencedirect.comenghttp://rightsstatements.org/vocab/InC/1.0/KohlendioxidWissenschaftlicher Artikel