Case study on the influence of synoptic-scale processes on the paired H₂O–O₃ distribution in the UTLS across a North Atlantic jet stream

Abstract. During a research flight of the Wave-driven ISentropic Exchange (WISE) campaign, which was conducted over eastern North Atlantic on 1 October 2017, composition upper troposphere and lower stratosphere (UTLS) across jet stream observed by airborne, range-resolved differential absorption lidar (DIAL) profiles. We investigate how high variability in paired H2O O3 distribution along two-dimensional cross section is affected synoptic-scale weather systems, as revealed Lagrangian history air masses. To this aim, observations are combined with 10 d backward trajectories meteorological parameters derived turbulence diagnostics traced. The transport mixing characteristics then projected to vertical sections measurements H2O–O3 phase space explore linkages evolution systems their interaction. Tropical, midlatitude, arctic region related explain complex large extent: O3-rich stratospheric from Arctic interacts midlatitude Pacific northward-deflected associated an anticyclone US forms filament extending into tropopause fold beneath stream. In troposphere, lifting convection intertropical convergence zone (ITCZ) two tropical cyclones that continuously injected dry descending form filamentary structures. One cyclone transitioned lifted moist boundary layer air, explaining highest tropospheric values. days before observations, mixed experienced frequent stream, indicating strong influence formation extratropical transition (ExTL). This investigation highlights complexity stirring processes close connection interacting tropics polar regions, strongly influenced fine-scale distributions. identified non-local character should be kept mind when interpreting lines tracer–tracer diagrams.