Widespread shallow mesoscale circulations observed in the trades
International audience Understanding the drivers of cloud organization is crucial for accurately estimating cloud feedbacks and their contribution to climate warming. Shallow mesoscale circulations are thought to play an important role in cloud organization, but they have not been observed. Here we...
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ftecoleponts:oai:HAL:insu-04195491v1 2023-11-05T03:43:59+01:00 Widespread shallow mesoscale circulations observed in the trades George, Geet Stevens, Bjorn Bony, Sandrine Vogel, Raphaela Naumann, Ann Kristin Laboratoire de Météorologie Dynamique (UMR 8539) (LMD) Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris École normale supérieure - Paris (ENS-PSL) Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL) Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL) 2023 https://insu.hal.science/insu-04195491 https://doi.org/10.1038/s41561-023-01215-1 en eng HAL CCSD Nature Publishing Group info:eu-repo/semantics/altIdentifier/doi/10.1038/s41561-023-01215-1 insu-04195491 https://insu.hal.science/insu-04195491 BIBCODE: 2023NatGe.16.584G doi:10.1038/s41561-023-01215-1 ISSN: 1752-0894 Nature Geoscience https://insu.hal.science/insu-04195491 Nature Geoscience, 2023, 16, pp.584-589. ⟨10.1038/s41561-023-01215-1⟩ [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/article Journal articles 2023 ftecoleponts https://doi.org/10.1038/s41561-023-01215-1 2023-10-11T16:15:42Z International audience Understanding the drivers of cloud organization is crucial for accurately estimating cloud feedbacks and their contribution to climate warming. Shallow mesoscale circulations are thought to play an important role in cloud organization, but they have not been observed. Here we present observational evidence for the existence of shallow mesoscale overturning circulations using divergence measurements made during the EUREC 4 A field campaign in the North Atlantic trades. Meteorological re-analyses reproduce the observed low-level divergence well and confirm the circulations to be mesoscale features (around 200 km across). We find that the shallow mesoscale circulations are associated with large variability in mesoscale vertical velocity and amplify moisture variance at the cloud base. Through their modulation of cloud-base moisture, the circulations influence how efficiently the subcloud layer dries, thus producing moist ascending branches and dry descending branches. The observed moisture variance differs from expectations from large-eddy simulations, which show the largest variance near the cloud top and negligible subcloud variance. The ubiquity of shallow mesoscale circulations, and their coupling to moisture and cloud fields, suggests that the strength and scale of mesoscale circulations are integral to determining how clouds respond to climate change. Article in Journal/Newspaper North Atlantic École des Ponts ParisTech: HAL Nature Geoscience 16 7 584 589 |
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[SDU]Sciences of the Universe [physics] |
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[SDU]Sciences of the Universe [physics] George, Geet Stevens, Bjorn Bony, Sandrine Vogel, Raphaela Naumann, Ann Kristin Widespread shallow mesoscale circulations observed in the trades |
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[SDU]Sciences of the Universe [physics] |
description |
International audience Understanding the drivers of cloud organization is crucial for accurately estimating cloud feedbacks and their contribution to climate warming. Shallow mesoscale circulations are thought to play an important role in cloud organization, but they have not been observed. Here we present observational evidence for the existence of shallow mesoscale overturning circulations using divergence measurements made during the EUREC 4 A field campaign in the North Atlantic trades. Meteorological re-analyses reproduce the observed low-level divergence well and confirm the circulations to be mesoscale features (around 200 km across). We find that the shallow mesoscale circulations are associated with large variability in mesoscale vertical velocity and amplify moisture variance at the cloud base. Through their modulation of cloud-base moisture, the circulations influence how efficiently the subcloud layer dries, thus producing moist ascending branches and dry descending branches. The observed moisture variance differs from expectations from large-eddy simulations, which show the largest variance near the cloud top and negligible subcloud variance. The ubiquity of shallow mesoscale circulations, and their coupling to moisture and cloud fields, suggests that the strength and scale of mesoscale circulations are integral to determining how clouds respond to climate change. |
author2 |
Laboratoire de Météorologie Dynamique (UMR 8539) (LMD) Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris École normale supérieure - Paris (ENS-PSL) Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL) Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL) |
format |
Article in Journal/Newspaper |
author |
George, Geet Stevens, Bjorn Bony, Sandrine Vogel, Raphaela Naumann, Ann Kristin |
author_facet |
George, Geet Stevens, Bjorn Bony, Sandrine Vogel, Raphaela Naumann, Ann Kristin |
author_sort |
George, Geet |
title |
Widespread shallow mesoscale circulations observed in the trades |
title_short |
Widespread shallow mesoscale circulations observed in the trades |
title_full |
Widespread shallow mesoscale circulations observed in the trades |
title_fullStr |
Widespread shallow mesoscale circulations observed in the trades |
title_full_unstemmed |
Widespread shallow mesoscale circulations observed in the trades |
title_sort |
widespread shallow mesoscale circulations observed in the trades |
publisher |
HAL CCSD |
publishDate |
2023 |
url |
https://insu.hal.science/insu-04195491 https://doi.org/10.1038/s41561-023-01215-1 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
ISSN: 1752-0894 Nature Geoscience https://insu.hal.science/insu-04195491 Nature Geoscience, 2023, 16, pp.584-589. ⟨10.1038/s41561-023-01215-1⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1038/s41561-023-01215-1 insu-04195491 https://insu.hal.science/insu-04195491 BIBCODE: 2023NatGe.16.584G doi:10.1038/s41561-023-01215-1 |
op_doi |
https://doi.org/10.1038/s41561-023-01215-1 |
container_title |
Nature Geoscience |
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16 |
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7 |
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584 |
op_container_end_page |
589 |
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