Spread of influence functions. Spatial distribution of influence function (averaged pairwise differences) over the two months (September–October 2013, 17–22UTC) representing the variability in the tower footprints across the different WRF-FDDA experiments. Note that numbers 1–12 indicate the tower locations as detailed in Figure 8 and two towers were not operational during the time period Oct 26–30. DOI: https://doi.org/10.1525/elementa.133.f10