Tropospheric transport climate partitioned by surface origin and transit time

We perform the first analysis of tropospheric transport using the global boundary propagator Green function, G, which partitions air at every point and time according to both the transit time since last surface contact and the location of that contact. We compute G for a 3-year period with the MATCH model driven by NCEP reanalyses. Last contact time is resolved in 3-d intervals, and last-contact location is resolved with a global tiling of 41 patches concentrated in the Northern Hemisphere. The transport climate is quantified for four midlatitude receptor regions in terms of the seasonal mean surface-origin and transit-time partitioning of the column burden, the surface flux of newly arriving air, and the distribution of air mass in transit from source to receptor surface. At long transit times a nearly receptor-independent pattern of last-contact location is governed by where air is injected into the upper troposphere by deep convection and the high terrain of Tibet. The receptor origin composition of the column burden changes only slowly after similar to 40 d for winter and fall, while the composition of the flux onto the receptor continues to change at similar to 60 d. European and SE Asian air contribute comparably to the flux onto eastern North America, in spite of SE Asian air having the dominant burden. The flux of European air onto SE Asia in winter and fall is larger than the flux of SE Asian air onto Europe. The surface-to-surface transport mass distribution, R, is used to identify transit-time-dependent source-receptor teleconnections.