Variability of low-level clouds over the southern oceans
International audience Climate model simulations of cloud radiative properties over the Southern Ocean (SO) show thatclouds reflect too little solar radiation compared with observations. This results in large errors inthe modelled sea surface temperature, atmospheric circulation and climate sensitiv...
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HAL CCSD
2022
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Online Access: | https://hal-insu.archives-ouvertes.fr/insu-03680894 https://doi.org/10.5194/egusphere-egu22-9550 |
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ftunivnantes:oai:HAL:insu-03680894v1 |
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Université de Nantes: HAL-UNIV-NANTES |
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ftunivnantes |
language |
English |
topic |
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph] |
spellingShingle |
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph] Bazantay, Clément Jourdan, Olivier Mioche, Guillaume Delanoë, Julien Cazenave, Quitterie Uitz, Julia Sellegri, Karine Variability of low-level clouds over the southern oceans |
topic_facet |
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph] |
description |
International audience Climate model simulations of cloud radiative properties over the Southern Ocean (SO) show thatclouds reflect too little solar radiation compared with observations. This results in large errors inthe modelled sea surface temperature, atmospheric circulation and climate sensitivity. Low-level(LL) mixed-phase clouds (MPCs) in the cold sectors of extratropical cyclones are identified as themain contributor to the SO radiation bias.In this study, LL clouds are investigated between 40°S and 82° S to provide a new insight into theirgeographical distribution, as well as their spatial and temporal variabilities. The methodologyrelies on DARDAR products which exploits the synergy of CALIPSO's lidar and CloudSat's radarspace-borne remote sensing observations. Based on DARDAR cloud-type products, a cloudclassification program was developed to establish cloud spatial and temporal distributions. Thisstudy concerns all types of cloud, including MPCs and supercooled-water containing clouds. Themean seasonal LL cloud cover for 2007-2010 over oceans (including sea-ice) varies from 64.4% inwinter to 68.4% in fall. Larger cloud covers are observed between 50°S and 65°S where clouds arepresent more than 80% of the time. Dividing the studied area into smaller regions allowed toextract homogeneous sectors in term of cloud coverage. This analysis draw attention on someregions, such as the Tasman Sea sector that undergoes the highest seasonal variations for MPCand USLC occurrence, and the Argentinian coasts that presents important differences with otherregions at the same latitudes. Over the Southern Ocean, the Weddell Sea sector stands out with arelatively low LL cloud occurrence.Statistical analyses were carried out to determine the influence of the meteorological andbiological conditions on cloud occurrence. Even though air temperature drives all cloud-typeoccurrences, it was found that the lower-tropospheric stability (LTS) is a good predictor of ice-cloud occurrence between 40°S and 50°S, particularly. With ... |
author2 |
Laboratoire de Météorologie Physique (LaMP) Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA) SPACE - LATMOS Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS) Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) Laboratoire d'océanographie de Villefranche (LOV) Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV) Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) |
format |
Conference Object |
author |
Bazantay, Clément Jourdan, Olivier Mioche, Guillaume Delanoë, Julien Cazenave, Quitterie Uitz, Julia Sellegri, Karine |
author_facet |
Bazantay, Clément Jourdan, Olivier Mioche, Guillaume Delanoë, Julien Cazenave, Quitterie Uitz, Julia Sellegri, Karine |
author_sort |
Bazantay, Clément |
title |
Variability of low-level clouds over the southern oceans |
title_short |
Variability of low-level clouds over the southern oceans |
title_full |
Variability of low-level clouds over the southern oceans |
title_fullStr |
Variability of low-level clouds over the southern oceans |
title_full_unstemmed |
Variability of low-level clouds over the southern oceans |
title_sort |
variability of low-level clouds over the southern oceans |
publisher |
HAL CCSD |
publishDate |
2022 |
url |
https://hal-insu.archives-ouvertes.fr/insu-03680894 https://doi.org/10.5194/egusphere-egu22-9550 |
op_coverage |
Online, France |
geographic |
Southern Ocean Weddell Weddell Sea |
geographic_facet |
Southern Ocean Weddell Weddell Sea |
genre |
Sea ice Southern Ocean Weddell Sea |
genre_facet |
Sea ice Southern Ocean Weddell Sea |
op_source |
EGU General Assembly 2022 https://hal-insu.archives-ouvertes.fr/insu-03680894 EGU General Assembly 2022, May 2022, Online, France. ⟨10.5194/egusphere-egu22-9550⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/egusphere-egu22-9550 insu-03680894 https://hal-insu.archives-ouvertes.fr/insu-03680894 doi:10.5194/egusphere-egu22-9550 |
op_doi |
https://doi.org/10.5194/egusphere-egu22-9550 |
_version_ |
1766195653226004480 |
spelling |
ftunivnantes:oai:HAL:insu-03680894v1 2023-05-15T18:18:54+02:00 Variability of low-level clouds over the southern oceans Bazantay, Clément Jourdan, Olivier Mioche, Guillaume Delanoë, Julien Cazenave, Quitterie Uitz, Julia Sellegri, Karine Laboratoire de Météorologie Physique (LaMP) Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA) SPACE - LATMOS Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS) Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) Laboratoire d'océanographie de Villefranche (LOV) Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV) Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) Online, France 2022-05 https://hal-insu.archives-ouvertes.fr/insu-03680894 https://doi.org/10.5194/egusphere-egu22-9550 en eng HAL CCSD info:eu-repo/semantics/altIdentifier/doi/10.5194/egusphere-egu22-9550 insu-03680894 https://hal-insu.archives-ouvertes.fr/insu-03680894 doi:10.5194/egusphere-egu22-9550 EGU General Assembly 2022 https://hal-insu.archives-ouvertes.fr/insu-03680894 EGU General Assembly 2022, May 2022, Online, France. ⟨10.5194/egusphere-egu22-9550⟩ [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph] info:eu-repo/semantics/conferenceObject Conference papers 2022 ftunivnantes https://doi.org/10.5194/egusphere-egu22-9550 2023-02-08T02:48:33Z International audience Climate model simulations of cloud radiative properties over the Southern Ocean (SO) show thatclouds reflect too little solar radiation compared with observations. This results in large errors inthe modelled sea surface temperature, atmospheric circulation and climate sensitivity. Low-level(LL) mixed-phase clouds (MPCs) in the cold sectors of extratropical cyclones are identified as themain contributor to the SO radiation bias.In this study, LL clouds are investigated between 40°S and 82° S to provide a new insight into theirgeographical distribution, as well as their spatial and temporal variabilities. The methodologyrelies on DARDAR products which exploits the synergy of CALIPSO's lidar and CloudSat's radarspace-borne remote sensing observations. Based on DARDAR cloud-type products, a cloudclassification program was developed to establish cloud spatial and temporal distributions. Thisstudy concerns all types of cloud, including MPCs and supercooled-water containing clouds. Themean seasonal LL cloud cover for 2007-2010 over oceans (including sea-ice) varies from 64.4% inwinter to 68.4% in fall. Larger cloud covers are observed between 50°S and 65°S where clouds arepresent more than 80% of the time. Dividing the studied area into smaller regions allowed toextract homogeneous sectors in term of cloud coverage. This analysis draw attention on someregions, such as the Tasman Sea sector that undergoes the highest seasonal variations for MPCand USLC occurrence, and the Argentinian coasts that presents important differences with otherregions at the same latitudes. Over the Southern Ocean, the Weddell Sea sector stands out with arelatively low LL cloud occurrence.Statistical analyses were carried out to determine the influence of the meteorological andbiological conditions on cloud occurrence. Even though air temperature drives all cloud-typeoccurrences, it was found that the lower-tropospheric stability (LTS) is a good predictor of ice-cloud occurrence between 40°S and 50°S, particularly. With ... Conference Object Sea ice Southern Ocean Weddell Sea Université de Nantes: HAL-UNIV-NANTES Southern Ocean Weddell Weddell Sea |