Clouds over Greenland observed by CALIPSO
Over 80% of Greenland is covered by ice. Melting of this ice contributes to the sea level rise. By modulating the radiation reaching the surface, clouds can accelerate or slow down the melting. Through this thesis, we use CALIPSO satellite measurements (GOCCP product) to document clouds over Greenla...
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ftecoleponts:oai:HAL:tel-01506120v2 2024-09-09T19:42:13+00:00 Clouds over Greenland observed by CALIPSO Les nuages du Groenland observés par CALIPSO Lacour, Adrien Laboratoire de Météorologie Dynamique (UMR 8539) (LMD) Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X) Institut Polytechnique de Paris (IP Paris)-Institut Polytechnique de Paris (IP Paris)-École des Ponts ParisTech (ENPC)-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) Université Pierre et Marie Curie - Paris VI Hélène Chepfer Vincent Noël 2016-12-13 https://theses.hal.science/tel-01506120 https://theses.hal.science/tel-01506120v2/document https://theses.hal.science/tel-01506120v2/file/these_archivage_3369457o.pdf fr fre HAL CCSD NNT: 2016PA066460 tel-01506120 https://theses.hal.science/tel-01506120 https://theses.hal.science/tel-01506120v2/document https://theses.hal.science/tel-01506120v2/file/these_archivage_3369457o.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-01506120 Océan, Atmosphère. Université Pierre et Marie Curie - Paris VI, 2016. Français. ⟨NNT : 2016PA066460⟩ Clouds Greenland Summit ground station Nuages Groenland Effet radiatif Calotte polaire Station sol de Summit Modèle de climat [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/doctoralThesis Theses 2016 ftecoleponts 2024-08-13T23:47:27Z Over 80% of Greenland is covered by ice. Melting of this ice contributes to the sea level rise. By modulating the radiation reaching the surface, clouds can accelerate or slow down the melting. Through this thesis, we use CALIPSO satellite measurements (GOCCP product) to document clouds over Greenland, including their vertical structure, and understand their role in surface melting.We compare these observations with radar and lidar measurement taken from the Summit ground station in the middle of Greenland. The comparison shows that GOCCP does not include optically thin ice clouds (τ < 0.3). Extending this analysis over all Greenland shows that cloudiness follows different cloud annual cycles in North and South regions, and that Summit is one of the cloudiest regions of the Greenland especially for the liquid cloud cover.To understand the atmospheric conditions favorable to cloud formation, we follow two weather regime classification approaches. We do not find a clear relationship between cloud variability and atmospheric circulation. These results show the complexity of the interactions between clouds and synoptic circulation and highlight the need to accumulate more data over long time periods.Finally, we evaluate cloud representation over Greenland in simulated lidar profiles over output from CMIP5 climate models. We identify several biases that lead to models being unable to simulate surface melting. Models underestimate the surface temperature and the cloud cover. Also when clouds are simulated they are either too opaque or too thin to affect surface melting. Plus de 80% du Groenland est recouvert de glace. Sa fonte contribue à l’augmentation du niveau des océans. Cette fonte peut être accélérée ou ralentie par les nuages qui modulent le rayonnement qui atteint la surface. Dans cette thèse, nous avons utilisé les mesures du satellite CALIPSO (produit GOCCP) pour documenter les nuages au-dessus du Groenland et éclaircir leur rôle sur la fonte de surface.Comparer ces observations avec des mesures radar ... Doctoral or Postdoctoral Thesis Greenland Groenland École des Ponts ParisTech: HAL Greenland |
institution |
Open Polar |
collection |
École des Ponts ParisTech: HAL |
op_collection_id |
ftecoleponts |
language |
French |
topic |
Clouds Greenland Summit ground station Nuages Groenland Effet radiatif Calotte polaire Station sol de Summit Modèle de climat [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
spellingShingle |
Clouds Greenland Summit ground station Nuages Groenland Effet radiatif Calotte polaire Station sol de Summit Modèle de climat [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere Lacour, Adrien Clouds over Greenland observed by CALIPSO |
topic_facet |
Clouds Greenland Summit ground station Nuages Groenland Effet radiatif Calotte polaire Station sol de Summit Modèle de climat [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
description |
Over 80% of Greenland is covered by ice. Melting of this ice contributes to the sea level rise. By modulating the radiation reaching the surface, clouds can accelerate or slow down the melting. Through this thesis, we use CALIPSO satellite measurements (GOCCP product) to document clouds over Greenland, including their vertical structure, and understand their role in surface melting.We compare these observations with radar and lidar measurement taken from the Summit ground station in the middle of Greenland. The comparison shows that GOCCP does not include optically thin ice clouds (τ < 0.3). Extending this analysis over all Greenland shows that cloudiness follows different cloud annual cycles in North and South regions, and that Summit is one of the cloudiest regions of the Greenland especially for the liquid cloud cover.To understand the atmospheric conditions favorable to cloud formation, we follow two weather regime classification approaches. We do not find a clear relationship between cloud variability and atmospheric circulation. These results show the complexity of the interactions between clouds and synoptic circulation and highlight the need to accumulate more data over long time periods.Finally, we evaluate cloud representation over Greenland in simulated lidar profiles over output from CMIP5 climate models. We identify several biases that lead to models being unable to simulate surface melting. Models underestimate the surface temperature and the cloud cover. Also when clouds are simulated they are either too opaque or too thin to affect surface melting. Plus de 80% du Groenland est recouvert de glace. Sa fonte contribue à l’augmentation du niveau des océans. Cette fonte peut être accélérée ou ralentie par les nuages qui modulent le rayonnement qui atteint la surface. Dans cette thèse, nous avons utilisé les mesures du satellite CALIPSO (produit GOCCP) pour documenter les nuages au-dessus du Groenland et éclaircir leur rôle sur la fonte de surface.Comparer ces observations avec des mesures radar ... |
author2 |
Laboratoire de Météorologie Dynamique (UMR 8539) (LMD) Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X) Institut Polytechnique de Paris (IP Paris)-Institut Polytechnique de Paris (IP Paris)-École des Ponts ParisTech (ENPC)-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) Université Pierre et Marie Curie - Paris VI Hélène Chepfer Vincent Noël |
format |
Doctoral or Postdoctoral Thesis |
author |
Lacour, Adrien |
author_facet |
Lacour, Adrien |
author_sort |
Lacour, Adrien |
title |
Clouds over Greenland observed by CALIPSO |
title_short |
Clouds over Greenland observed by CALIPSO |
title_full |
Clouds over Greenland observed by CALIPSO |
title_fullStr |
Clouds over Greenland observed by CALIPSO |
title_full_unstemmed |
Clouds over Greenland observed by CALIPSO |
title_sort |
clouds over greenland observed by calipso |
publisher |
HAL CCSD |
publishDate |
2016 |
url |
https://theses.hal.science/tel-01506120 https://theses.hal.science/tel-01506120v2/document https://theses.hal.science/tel-01506120v2/file/these_archivage_3369457o.pdf |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Groenland |
genre_facet |
Greenland Groenland |
op_source |
https://theses.hal.science/tel-01506120 Océan, Atmosphère. Université Pierre et Marie Curie - Paris VI, 2016. Français. ⟨NNT : 2016PA066460⟩ |
op_relation |
NNT: 2016PA066460 tel-01506120 https://theses.hal.science/tel-01506120 https://theses.hal.science/tel-01506120v2/document https://theses.hal.science/tel-01506120v2/file/these_archivage_3369457o.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1809911502226849792 |