“…Studies have long shown that transport computations using analyzed winds are very sensitive to how the large-scale flow is specified (e.g., Schoeberl et al, 2003;Meijer et al, 2004;Pawson et al, 2007). However, for historical reasons these sensitivities have been most rigorously explored in the context of offline chemical transport models (CTMs) and Lagrangian trajectory models, with several studies demonstrating the sensitivity of stratospheric transport to both the temporal sampling and averaging of the prescribed fields (e.g., Waugh et al, 1997;Bregman et al, 2006;Legras et al, 2005;Pawson et al, 2007;Monge-Sanz et al, 2007, 2013. By comparison, relatively less attention has been paid to assessing the credibility of large-scale transport in simulations using general circulation models constrained with reanalysis products either using so-called "nudging", wherein the simulated meteorological fields are relaxed towards analysis fields (Kunz et al, 2012), or using approaches derived from data assimilation (e.g., Orbe et al, 2017b).…”