Fig. 3From: Investigating regional source and sink patterns of Alpine CO2 and CH4 concentrations based on a back trajectory receptor modelFootprints of the centroid pathways from the site-specific FLEXPART particle dispersion modelling for the receptor observatories Jungfraujoch (JFJ), Plateau Rosa (PRO), Sonnblick (SOB) and Schneefernerhaus (UFS), respectively, visualising the frequentation of the 0.2 × 0.2° grid cells within the individual catchment area by the backward trajectories during the study period 2011–2015Back to article page