Water isotopic characterisation of the cloud–circulation coupling in the North Atlantic trades – Part 2: The imprint of the atmospheric circulation at different scales
Water vapour isotopes reflect the history of moist atmospheric processes encountered by the vapour since evaporating from the ocean, offering potential insights into the controls of shallow trade-wind cumuli. Given that these clouds, particularly their amount at the cloud base level, play an importa...
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Online Access: | https://doi.org/10.5194/acp-24-957-2024 https://acp.copernicus.org/articles/24/957/2024/ |
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ftcopernicus:oai:publications.copernicus.org:acp110130 2024-09-15T18:23:44+00:00 Water isotopic characterisation of the cloud–circulation coupling in the North Atlantic trades – Part 2: The imprint of the atmospheric circulation at different scales Villiger, Leonie Aemisegger, Franziska 2024-01-23 application/pdf https://doi.org/10.5194/acp-24-957-2024 https://acp.copernicus.org/articles/24/957/2024/ eng eng doi:10.5194/acp-24-957-2024 https://acp.copernicus.org/articles/24/957/2024/ eISSN: 1680-7324 Text 2024 ftcopernicus https://doi.org/10.5194/acp-24-957-2024 2024-08-28T05:24:15Z Water vapour isotopes reflect the history of moist atmospheric processes encountered by the vapour since evaporating from the ocean, offering potential insights into the controls of shallow trade-wind cumuli. Given that these clouds, particularly their amount at the cloud base level, play an important role in the global radiative budget, improving our understanding of the hydrological cycle associated with them is crucial. This study examines the variability of water vapour isotopes at cloud base in the winter trades near Barbados and explores its connection to the atmospheric circulations ultimately governing cloud fraction. The analyses are based on nested COSMO iso simulations with explicit convection during the EUREC 4 A (Elucidating the role of clouds-circulation coupling in climate) field campaign. It is shown that the contrasting isotope and humidity characteristics in clear-sky versus cloudy environments at cloud base emerge due to vertical transport on timescales of 4 to 14 h associated with local, convective circulations. In addition, the cloud base isotopes are sensitive to variations in the large-scale circulation on timescales of 4 to 6 d, which shows on average a Hadley-type subsidence but occasionally much stronger descent related to extratropical dry intrusions. This investigation, based on high-resolution isotope-enabled simulations in combination with trajectory analyses, reveals how dynamical processes at different timescales act in concert to produce the observed humidity variations at the base of trade-wind cumuli. Text North Atlantic Copernicus Publications: E-Journals Atmospheric Chemistry and Physics 24 2 957 976 |
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Copernicus Publications: E-Journals |
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ftcopernicus |
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English |
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Water vapour isotopes reflect the history of moist atmospheric processes encountered by the vapour since evaporating from the ocean, offering potential insights into the controls of shallow trade-wind cumuli. Given that these clouds, particularly their amount at the cloud base level, play an important role in the global radiative budget, improving our understanding of the hydrological cycle associated with them is crucial. This study examines the variability of water vapour isotopes at cloud base in the winter trades near Barbados and explores its connection to the atmospheric circulations ultimately governing cloud fraction. The analyses are based on nested COSMO iso simulations with explicit convection during the EUREC 4 A (Elucidating the role of clouds-circulation coupling in climate) field campaign. It is shown that the contrasting isotope and humidity characteristics in clear-sky versus cloudy environments at cloud base emerge due to vertical transport on timescales of 4 to 14 h associated with local, convective circulations. In addition, the cloud base isotopes are sensitive to variations in the large-scale circulation on timescales of 4 to 6 d, which shows on average a Hadley-type subsidence but occasionally much stronger descent related to extratropical dry intrusions. This investigation, based on high-resolution isotope-enabled simulations in combination with trajectory analyses, reveals how dynamical processes at different timescales act in concert to produce the observed humidity variations at the base of trade-wind cumuli. |
format |
Text |
author |
Villiger, Leonie Aemisegger, Franziska |
spellingShingle |
Villiger, Leonie Aemisegger, Franziska Water isotopic characterisation of the cloud–circulation coupling in the North Atlantic trades – Part 2: The imprint of the atmospheric circulation at different scales |
author_facet |
Villiger, Leonie Aemisegger, Franziska |
author_sort |
Villiger, Leonie |
title |
Water isotopic characterisation of the cloud–circulation coupling in the North Atlantic trades – Part 2: The imprint of the atmospheric circulation at different scales |
title_short |
Water isotopic characterisation of the cloud–circulation coupling in the North Atlantic trades – Part 2: The imprint of the atmospheric circulation at different scales |
title_full |
Water isotopic characterisation of the cloud–circulation coupling in the North Atlantic trades – Part 2: The imprint of the atmospheric circulation at different scales |
title_fullStr |
Water isotopic characterisation of the cloud–circulation coupling in the North Atlantic trades – Part 2: The imprint of the atmospheric circulation at different scales |
title_full_unstemmed |
Water isotopic characterisation of the cloud–circulation coupling in the North Atlantic trades – Part 2: The imprint of the atmospheric circulation at different scales |
title_sort |
water isotopic characterisation of the cloud–circulation coupling in the north atlantic trades – part 2: the imprint of the atmospheric circulation at different scales |
publishDate |
2024 |
url |
https://doi.org/10.5194/acp-24-957-2024 https://acp.copernicus.org/articles/24/957/2024/ |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
eISSN: 1680-7324 |
op_relation |
doi:10.5194/acp-24-957-2024 https://acp.copernicus.org/articles/24/957/2024/ |
op_doi |
https://doi.org/10.5194/acp-24-957-2024 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
24 |
container_issue |
2 |
container_start_page |
957 |
op_container_end_page |
976 |
_version_ |
1810463992043274240 |