Influence of oceanic small-scale variability associated with the Gulf Stream on air-sea interactions and impact on North Atlantic atmospheric variability
This thesis aims at analyzing the influence of small-scale spatial variability of the sea surface temperature (SST) over an oceanic front on the climate variability at mid-latitudes. We focus on the effect of the Gulf Stream SST front on the marine atmospheric boundary layer and the free troposphere...
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Format: | Doctoral or Postdoctoral Thesis |
Language: | French |
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Online Access: | https://theses.hal.science/tel-01230012 https://theses.hal.science/tel-01230012/document https://theses.hal.science/tel-01230012/file/2015TOU30065.pdf |
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ftunivnantes:oai:HAL:tel-01230012v1 2023-05-15T17:29:02+02:00 Influence of oceanic small-scale variability associated with the Gulf Stream on air-sea interactions and impact on North Atlantic atmospheric variability Influence des petites échelles océaniques associées au Gulf Stream sur les interactions air-mer et impact sur la variabilité atmosphérique de l'Atlantique Nord Piazza, Marie Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS) Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique - CERFACS (CERFACS) Université Toulouse 3 Paul Sabatier Laurent Terray Julien Boé ANR-11-BS56-0014,ASIV,Interactions Océan-Atmosphère. Influence des gradients de SST et de la haute résolution sur la variabilité atmosphérique(2011) 2015-01-30 https://theses.hal.science/tel-01230012 https://theses.hal.science/tel-01230012/document https://theses.hal.science/tel-01230012/file/2015TOU30065.pdf fr fre HAL CCSD NNT: 2015TOU30065 tel-01230012 https://theses.hal.science/tel-01230012 https://theses.hal.science/tel-01230012/document https://theses.hal.science/tel-01230012/file/2015TOU30065.pdf http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-01230012 Océan, Atmosphère. Université Toulouse 3 Paul Sabatier, 2015. Français. ⟨NNT : 2015TOU30065⟩ ocean-atmosphere coupling small-scale air-sea interaction climate variability at midlatitudes North Atlantic storm track SST front couplage océan-atmosphère interaction air-mer de petite échelle variabilité climatique aux moyennes latitudes route dépressionnaire de l'Atlantique Nord Gulf Stream front océanique [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation info:eu-repo/semantics/doctoralThesis Theses 2015 ftunivnantes 2023-02-08T10:29:23Z This thesis aims at analyzing the influence of small-scale spatial variability of the sea surface temperature (SST) over an oceanic front on the climate variability at mid-latitudes. We focus on the effect of the Gulf Stream SST front on the marine atmospheric boundary layer and the free troposphere, and on the large-scale atmospheric variability over the Euro-North Atlantic basin. We follow an approach based on numerical experiments with a high resolution (approximately 50 km at mid-latitudes) global atmospheric model, first forced with daily observed SST then coupled with a dynamical oceanic model. The first part of this thesis deal with the effects of small-scale oceanic forcing on the atmosphere locally and on the large-scale variability over the North Atlantic, at seasonal to inter-annual timescales. Two ensembles (with 4 members) of forced simulations are performed, the first one with global SST at high resolution (0.25°) and the other one with smoothed SST at 4° in the Gulf Stream region, in order to filter the small-scale spatial variability on the frontal area. Locally, the model captures the response of the SST small-scale forcing on the small-scale spatial variability of wind-speed at surface during winter, but with an underestimation of about 1/3 compared to the observations. The evaluation of the model compared to reanalysis shows that the large-scale spatial variability (jet stream, weather regimes) is well reproduce at mid-latitudes over North Atlantic and Europe. Comparison between the two experiments shows that the influence of small-scale spatial variations of the SST in the Gulf Stream region deeply affect the atmospheric column and reach the free troposphere (wind convergence at surface due to pressure adjustment in the boundary layer, turbulent heat fluxes at surface increase due to boundary layer destabilization, convective precipitations increase on the southern (warmer) part of the front and decrease on the northern (cooler) part). Locally, extra-tropical storms show an increase of the ... Doctoral or Postdoctoral Thesis North Atlantic Université de Nantes: HAL-UNIV-NANTES |
institution |
Open Polar |
collection |
Université de Nantes: HAL-UNIV-NANTES |
op_collection_id |
ftunivnantes |
language |
French |
topic |
ocean-atmosphere coupling small-scale air-sea interaction climate variability at midlatitudes North Atlantic storm track SST front couplage océan-atmosphère interaction air-mer de petite échelle variabilité climatique aux moyennes latitudes route dépressionnaire de l'Atlantique Nord Gulf Stream front océanique [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation |
spellingShingle |
ocean-atmosphere coupling small-scale air-sea interaction climate variability at midlatitudes North Atlantic storm track SST front couplage océan-atmosphère interaction air-mer de petite échelle variabilité climatique aux moyennes latitudes route dépressionnaire de l'Atlantique Nord Gulf Stream front océanique [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation Piazza, Marie Influence of oceanic small-scale variability associated with the Gulf Stream on air-sea interactions and impact on North Atlantic atmospheric variability |
topic_facet |
ocean-atmosphere coupling small-scale air-sea interaction climate variability at midlatitudes North Atlantic storm track SST front couplage océan-atmosphère interaction air-mer de petite échelle variabilité climatique aux moyennes latitudes route dépressionnaire de l'Atlantique Nord Gulf Stream front océanique [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation |
description |
This thesis aims at analyzing the influence of small-scale spatial variability of the sea surface temperature (SST) over an oceanic front on the climate variability at mid-latitudes. We focus on the effect of the Gulf Stream SST front on the marine atmospheric boundary layer and the free troposphere, and on the large-scale atmospheric variability over the Euro-North Atlantic basin. We follow an approach based on numerical experiments with a high resolution (approximately 50 km at mid-latitudes) global atmospheric model, first forced with daily observed SST then coupled with a dynamical oceanic model. The first part of this thesis deal with the effects of small-scale oceanic forcing on the atmosphere locally and on the large-scale variability over the North Atlantic, at seasonal to inter-annual timescales. Two ensembles (with 4 members) of forced simulations are performed, the first one with global SST at high resolution (0.25°) and the other one with smoothed SST at 4° in the Gulf Stream region, in order to filter the small-scale spatial variability on the frontal area. Locally, the model captures the response of the SST small-scale forcing on the small-scale spatial variability of wind-speed at surface during winter, but with an underestimation of about 1/3 compared to the observations. The evaluation of the model compared to reanalysis shows that the large-scale spatial variability (jet stream, weather regimes) is well reproduce at mid-latitudes over North Atlantic and Europe. Comparison between the two experiments shows that the influence of small-scale spatial variations of the SST in the Gulf Stream region deeply affect the atmospheric column and reach the free troposphere (wind convergence at surface due to pressure adjustment in the boundary layer, turbulent heat fluxes at surface increase due to boundary layer destabilization, convective precipitations increase on the southern (warmer) part of the front and decrease on the northern (cooler) part). Locally, extra-tropical storms show an increase of the ... |
author2 |
Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS) Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique - CERFACS (CERFACS) Université Toulouse 3 Paul Sabatier Laurent Terray Julien Boé ANR-11-BS56-0014,ASIV,Interactions Océan-Atmosphère. Influence des gradients de SST et de la haute résolution sur la variabilité atmosphérique(2011) |
format |
Doctoral or Postdoctoral Thesis |
author |
Piazza, Marie |
author_facet |
Piazza, Marie |
author_sort |
Piazza, Marie |
title |
Influence of oceanic small-scale variability associated with the Gulf Stream on air-sea interactions and impact on North Atlantic atmospheric variability |
title_short |
Influence of oceanic small-scale variability associated with the Gulf Stream on air-sea interactions and impact on North Atlantic atmospheric variability |
title_full |
Influence of oceanic small-scale variability associated with the Gulf Stream on air-sea interactions and impact on North Atlantic atmospheric variability |
title_fullStr |
Influence of oceanic small-scale variability associated with the Gulf Stream on air-sea interactions and impact on North Atlantic atmospheric variability |
title_full_unstemmed |
Influence of oceanic small-scale variability associated with the Gulf Stream on air-sea interactions and impact on North Atlantic atmospheric variability |
title_sort |
influence of oceanic small-scale variability associated with the gulf stream on air-sea interactions and impact on north atlantic atmospheric variability |
publisher |
HAL CCSD |
publishDate |
2015 |
url |
https://theses.hal.science/tel-01230012 https://theses.hal.science/tel-01230012/document https://theses.hal.science/tel-01230012/file/2015TOU30065.pdf |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
https://theses.hal.science/tel-01230012 Océan, Atmosphère. Université Toulouse 3 Paul Sabatier, 2015. Français. ⟨NNT : 2015TOU30065⟩ |
op_relation |
NNT: 2015TOU30065 tel-01230012 https://theses.hal.science/tel-01230012 https://theses.hal.science/tel-01230012/document https://theses.hal.science/tel-01230012/file/2015TOU30065.pdf |
op_rights |
http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess |
_version_ |
1766122344330297344 |