Disentangling different moisture transport pathways over the eastern subtropical North Atlantic using multi-platform isotope observations and high-resolution numerical modelling
Due to its dryness, the subtropical free troposphere plays a critical role in the radiative balance of the Earth's climate system. But the complex interactions of the dynamical and physical processes controlling the variability in the moisture budget of this sensitive region of the subtropical...
Published in: | Journal of Geophysical Research: Oceans |
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Online Access: | https://refubium.fu-berlin.de/handle/fub188/33058 https://doi.org/10.17169/refubium-32782 https://doi.org/10.5194/acp-21-16319-2021 |
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ftfuberlin:oai:refubium.fu-berlin.de:fub188/33058 2023-05-15T17:30:11+02:00 Disentangling different moisture transport pathways over the eastern subtropical North Atlantic using multi-platform isotope observations and high-resolution numerical modelling Dahinden, Fabienne Aemisegger, Franziska Wernli, Heini Schneider, Matthias Diekmann, Christopher J. Ertl, Benjamin Knippertz, Peter Werner, Martin Pfahl, Stephan 2021 29 Seiten application/pdf https://refubium.fu-berlin.de/handle/fub188/33058 https://doi.org/10.17169/refubium-32782 https://doi.org/10.5194/acp-21-16319-2021 eng eng https://refubium.fu-berlin.de/handle/fub188/33058 http://dx.doi.org/10.17169/refubium-32782 doi:10.5194/acp-21-16319-2021 https://creativecommons.org/licenses/by/4.0/ CC-BY moisture transport pathways eastern subtropical North Atlantic subtropical free troposphere ddc:550 doc-type:article 2021 ftfuberlin https://doi.org/10.17169/refubium-32782 https://doi.org/10.5194/acp-21-16319-2021 2022-06-12T22:23:51Z Due to its dryness, the subtropical free troposphere plays a critical role in the radiative balance of the Earth's climate system. But the complex interactions of the dynamical and physical processes controlling the variability in the moisture budget of this sensitive region of the subtropical atmosphere are still not fully understood. Stable water isotopes can provide important information about several of the latter processes, namely subsidence drying, turbulent mixing, and dry and moist convective moistening. In this study, we use high-resolution simulations of the isotope-enabled version of the regional weather and climate prediction model of the Consortium for Small-Scale Modelling (COSMOiso) to investigate predominant moisture transport pathways in the Canary Islands region in the eastern subtropical North Atlantic. Comparison of the simulated isotope signals with multi-platform isotope observations (aircraft, ground- and space-based remote sensing) from a field campaign in summer 2013 shows that COSMOiso can reproduce the observed variability of stable water vapour isotopes on timescales of hours to days, thus allowing us to study the mechanisms that control the subtropical free-tropospheric humidity. Changes in isotopic signals along backward trajectories from the Canary Islands region reveal the physical processes behind the synoptic-scale isotope variability. We identify four predominant moisture transport pathways of mid-tropospheric air, each with distinct isotopic signatures: 1. air parcels originating from the convective boundary layer of the Saharan heat low (SHL) - these are characterised by a homogeneous isotopic composition with a particularly high delta D (median mid-tropospheric delta D = -122 parts per thousand), which results from dry convective mixing of low-level moisture of diverse origin advected into the SHL; 2. air parcels originating from the free troposphere above the SHL - although experiencing the largest changes in humidity and delta D during their subsidence over West Africa, ... Article in Journal/Newspaper North Atlantic Freie Universität Berlin: Refubium (FU Berlin) Journal of Geophysical Research: Oceans 105 C3 6307 6326 |
institution |
Open Polar |
collection |
Freie Universität Berlin: Refubium (FU Berlin) |
op_collection_id |
ftfuberlin |
language |
English |
topic |
moisture transport pathways eastern subtropical North Atlantic subtropical free troposphere ddc:550 |
spellingShingle |
moisture transport pathways eastern subtropical North Atlantic subtropical free troposphere ddc:550 Dahinden, Fabienne Aemisegger, Franziska Wernli, Heini Schneider, Matthias Diekmann, Christopher J. Ertl, Benjamin Knippertz, Peter Werner, Martin Pfahl, Stephan Disentangling different moisture transport pathways over the eastern subtropical North Atlantic using multi-platform isotope observations and high-resolution numerical modelling |
topic_facet |
moisture transport pathways eastern subtropical North Atlantic subtropical free troposphere ddc:550 |
description |
Due to its dryness, the subtropical free troposphere plays a critical role in the radiative balance of the Earth's climate system. But the complex interactions of the dynamical and physical processes controlling the variability in the moisture budget of this sensitive region of the subtropical atmosphere are still not fully understood. Stable water isotopes can provide important information about several of the latter processes, namely subsidence drying, turbulent mixing, and dry and moist convective moistening. In this study, we use high-resolution simulations of the isotope-enabled version of the regional weather and climate prediction model of the Consortium for Small-Scale Modelling (COSMOiso) to investigate predominant moisture transport pathways in the Canary Islands region in the eastern subtropical North Atlantic. Comparison of the simulated isotope signals with multi-platform isotope observations (aircraft, ground- and space-based remote sensing) from a field campaign in summer 2013 shows that COSMOiso can reproduce the observed variability of stable water vapour isotopes on timescales of hours to days, thus allowing us to study the mechanisms that control the subtropical free-tropospheric humidity. Changes in isotopic signals along backward trajectories from the Canary Islands region reveal the physical processes behind the synoptic-scale isotope variability. We identify four predominant moisture transport pathways of mid-tropospheric air, each with distinct isotopic signatures: 1. air parcels originating from the convective boundary layer of the Saharan heat low (SHL) - these are characterised by a homogeneous isotopic composition with a particularly high delta D (median mid-tropospheric delta D = -122 parts per thousand), which results from dry convective mixing of low-level moisture of diverse origin advected into the SHL; 2. air parcels originating from the free troposphere above the SHL - although experiencing the largest changes in humidity and delta D during their subsidence over West Africa, ... |
format |
Article in Journal/Newspaper |
author |
Dahinden, Fabienne Aemisegger, Franziska Wernli, Heini Schneider, Matthias Diekmann, Christopher J. Ertl, Benjamin Knippertz, Peter Werner, Martin Pfahl, Stephan |
author_facet |
Dahinden, Fabienne Aemisegger, Franziska Wernli, Heini Schneider, Matthias Diekmann, Christopher J. Ertl, Benjamin Knippertz, Peter Werner, Martin Pfahl, Stephan |
author_sort |
Dahinden, Fabienne |
title |
Disentangling different moisture transport pathways over the eastern subtropical North Atlantic using multi-platform isotope observations and high-resolution numerical modelling |
title_short |
Disentangling different moisture transport pathways over the eastern subtropical North Atlantic using multi-platform isotope observations and high-resolution numerical modelling |
title_full |
Disentangling different moisture transport pathways over the eastern subtropical North Atlantic using multi-platform isotope observations and high-resolution numerical modelling |
title_fullStr |
Disentangling different moisture transport pathways over the eastern subtropical North Atlantic using multi-platform isotope observations and high-resolution numerical modelling |
title_full_unstemmed |
Disentangling different moisture transport pathways over the eastern subtropical North Atlantic using multi-platform isotope observations and high-resolution numerical modelling |
title_sort |
disentangling different moisture transport pathways over the eastern subtropical north atlantic using multi-platform isotope observations and high-resolution numerical modelling |
publishDate |
2021 |
url |
https://refubium.fu-berlin.de/handle/fub188/33058 https://doi.org/10.17169/refubium-32782 https://doi.org/10.5194/acp-21-16319-2021 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
https://refubium.fu-berlin.de/handle/fub188/33058 http://dx.doi.org/10.17169/refubium-32782 doi:10.5194/acp-21-16319-2021 |
op_rights |
https://creativecommons.org/licenses/by/4.0/ |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.17169/refubium-32782 https://doi.org/10.5194/acp-21-16319-2021 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
105 |
container_issue |
C3 |
container_start_page |
6307 |
op_container_end_page |
6326 |
_version_ |
1766126018938011648 |