Case study on the influence of synoptic-scale processes on the paired H<sub>2</sub>O–O<sub>3</sub> distribution in the UTLS across a North Atlantic jet stream

<p>During a research flight of the Wave-driven ISentropic Exchange (WISE) campaign, which was conducted over the eastern North Atlantic on 1 October 2017, the composition of the upper troposphere and lower stratosphere (UTLS) across the North Atlantic jet stream was observed by airborne, range...

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Main Authors: A. Schäfler, M. Sprenger, H. Wernli, A. Fix, M. Wirth
Format: Article
Language:English
Published: Copernicus Publications 2023-01-01
Series:Atmospheric Chemistry and Physics
Online Access:https://acp.copernicus.org/articles/23/999/2023/acp-23-999-2023.pdf
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author A. Schäfler
M. Sprenger
H. Wernli
A. Fix
M. Wirth
author_facet A. Schäfler
M. Sprenger
H. Wernli
A. Fix
M. Wirth
author_sort A. Schäfler
collection DOAJ
description <p>During a research flight of the Wave-driven ISentropic Exchange (WISE) campaign, which was conducted over the eastern North Atlantic on 1 October 2017, the composition of the upper troposphere and lower stratosphere (UTLS) across the North Atlantic jet stream was observed by airborne, range-resolved differential absorption lidar (DIAL) profiles. We investigate how the high variability in the paired H<span class="inline-formula"><sub>2</sub></span>O and O<span class="inline-formula"><sub>3</sub></span> distribution along the two-dimensional lidar cross section is affected by synoptic-scale weather systems, as revealed by the Lagrangian history of the observed air masses. To this aim, the lidar observations are combined with 10 d backward trajectories along which meteorological parameters and derived turbulence diagnostics are traced. The transport and mixing characteristics are then projected to the vertical cross sections of the lidar measurements and to the H<span class="inline-formula"><sub>2</sub></span>O–O<span class="inline-formula"><sub>3</sub></span> phase space to explore linkages with the evolution of synoptic-scale weather systems and their interaction. Tropical, midlatitude, and arctic weather systems in the region of the jet stream and the related transport and mixing explain the complex H<span class="inline-formula"><sub>2</sub></span>O and O<span class="inline-formula"><sub>3</sub></span> distribution to a large extent: O<span class="inline-formula"><sub>3</sub></span>-rich stratospheric air from the high Arctic interacts with midlatitude air from the North Pacific in a northward-deflected jet stream associated with an anticyclone over the US and forms a filament extending into the tropopause fold beneath the jet stream. In the troposphere, lifting related to convection in the intertropical convergence zone (ITCZ) and two tropical cyclones that continuously injected H<span class="inline-formula"><sub>2</sub></span>O into dry descending air from the tropical Atlantic and Pacific form filamentary H<span class="inline-formula"><sub>2</sub></span>O structures. One tropical cyclone that transitioned into a midlatitude cyclone lifted moist boundary layer air, explaining the highest tropospheric H<span class="inline-formula"><sub>2</sub></span>O values. During the two days before the observations, the air with mixed tropospheric and stratospheric characteristics experienced frequent turbulence along the North Atlantic jet stream, indicating a strong influence of turbulence on the formation of the extratropical transition layer (ExTL). This investigation highlights the complexity of stirring and mixing processes and their close connection to interacting tropospheric weather systems from the tropics to the polar regions, which strongly influenced the observed fine-scale H<span class="inline-formula"><sub>2</sub></span>O and O<span class="inline-formula"><sub>3</sub></span> distributions. The identified non-local character of mixing should be kept in mind when interpreting mixing lines in tracer–tracer phase space diagrams.</p>
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spelling doaj.art-7a189502a1f341d59271b220b34952fc2023-01-20T09:01:13ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242023-01-0123999101810.5194/acp-23-999-2023Case study on the influence of synoptic-scale processes on the paired H<sub>2</sub>O–O<sub>3</sub> distribution in the UTLS across a North Atlantic jet streamA. Schäfler0M. Sprenger1H. Wernli2A. Fix3M. Wirth4Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, GermanyInstitute for Atmospheric and Climate Science, ETH Zurich, Zurich, SwitzerlandInstitute for Atmospheric and Climate Science, ETH Zurich, Zurich, SwitzerlandDeutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, GermanyDeutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany<p>During a research flight of the Wave-driven ISentropic Exchange (WISE) campaign, which was conducted over the eastern North Atlantic on 1 October 2017, the composition of the upper troposphere and lower stratosphere (UTLS) across the North Atlantic jet stream was observed by airborne, range-resolved differential absorption lidar (DIAL) profiles. We investigate how the high variability in the paired H<span class="inline-formula"><sub>2</sub></span>O and O<span class="inline-formula"><sub>3</sub></span> distribution along the two-dimensional lidar cross section is affected by synoptic-scale weather systems, as revealed by the Lagrangian history of the observed air masses. To this aim, the lidar observations are combined with 10 d backward trajectories along which meteorological parameters and derived turbulence diagnostics are traced. The transport and mixing characteristics are then projected to the vertical cross sections of the lidar measurements and to the H<span class="inline-formula"><sub>2</sub></span>O–O<span class="inline-formula"><sub>3</sub></span> phase space to explore linkages with the evolution of synoptic-scale weather systems and their interaction. Tropical, midlatitude, and arctic weather systems in the region of the jet stream and the related transport and mixing explain the complex H<span class="inline-formula"><sub>2</sub></span>O and O<span class="inline-formula"><sub>3</sub></span> distribution to a large extent: O<span class="inline-formula"><sub>3</sub></span>-rich stratospheric air from the high Arctic interacts with midlatitude air from the North Pacific in a northward-deflected jet stream associated with an anticyclone over the US and forms a filament extending into the tropopause fold beneath the jet stream. In the troposphere, lifting related to convection in the intertropical convergence zone (ITCZ) and two tropical cyclones that continuously injected H<span class="inline-formula"><sub>2</sub></span>O into dry descending air from the tropical Atlantic and Pacific form filamentary H<span class="inline-formula"><sub>2</sub></span>O structures. One tropical cyclone that transitioned into a midlatitude cyclone lifted moist boundary layer air, explaining the highest tropospheric H<span class="inline-formula"><sub>2</sub></span>O values. During the two days before the observations, the air with mixed tropospheric and stratospheric characteristics experienced frequent turbulence along the North Atlantic jet stream, indicating a strong influence of turbulence on the formation of the extratropical transition layer (ExTL). This investigation highlights the complexity of stirring and mixing processes and their close connection to interacting tropospheric weather systems from the tropics to the polar regions, which strongly influenced the observed fine-scale H<span class="inline-formula"><sub>2</sub></span>O and O<span class="inline-formula"><sub>3</sub></span> distributions. The identified non-local character of mixing should be kept in mind when interpreting mixing lines in tracer–tracer phase space diagrams.</p>https://acp.copernicus.org/articles/23/999/2023/acp-23-999-2023.pdf
spellingShingle A. Schäfler
M. Sprenger
H. Wernli
A. Fix
M. Wirth
Case study on the influence of synoptic-scale processes on the paired H<sub>2</sub>O–O<sub>3</sub> distribution in the UTLS across a North Atlantic jet stream
Atmospheric Chemistry and Physics
title Case study on the influence of synoptic-scale processes on the paired H<sub>2</sub>O–O<sub>3</sub> distribution in the UTLS across a North Atlantic jet stream
title_full Case study on the influence of synoptic-scale processes on the paired H<sub>2</sub>O–O<sub>3</sub> distribution in the UTLS across a North Atlantic jet stream
title_fullStr Case study on the influence of synoptic-scale processes on the paired H<sub>2</sub>O–O<sub>3</sub> distribution in the UTLS across a North Atlantic jet stream
title_full_unstemmed Case study on the influence of synoptic-scale processes on the paired H<sub>2</sub>O–O<sub>3</sub> distribution in the UTLS across a North Atlantic jet stream
title_short Case study on the influence of synoptic-scale processes on the paired H<sub>2</sub>O–O<sub>3</sub> distribution in the UTLS across a North Atlantic jet stream
title_sort case study on the influence of synoptic scale processes on the paired h sub 2 sub o o sub 3 sub distribution in the utls across a north atlantic jet stream
url https://acp.copernicus.org/articles/23/999/2023/acp-23-999-2023.pdf
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