Air-sea interactions over the Gulf Stream region : benefits of higher-resolution in the representation of the physical mechanisms and climate impacts
This thesis aims at understanding the role of sea surface temperature (SST) fronts on air-sea interactions in the Gulf Stream region. We study the local response of the atmosphere to the SST mesoscale variability, not only within the marine atmospheric boundary layer (MABL), but also in the free tro...
Main Author: | |
---|---|
Other Authors: | , , , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | French |
Published: |
HAL CCSD
2020
|
Subjects: | |
Online Access: | https://theses.hal.science/tel-03667341 https://theses.hal.science/tel-03667341/document https://theses.hal.science/tel-03667341/file/2020TOU30318b.pdf |
id |
ftinsu:oai:HAL:tel-03667341v1 |
---|---|
record_format |
openpolar |
spelling |
ftinsu:oai:HAL:tel-03667341v1 2023-06-18T03:42:11+02:00 Air-sea interactions over the Gulf Stream region : benefits of higher-resolution in the representation of the physical mechanisms and climate impacts Étude des interactions océan-atmosphère sur le Gulf Stream : apport de la haute résolution sur la représentation des mécanismes physiques et des impacts climatiques Rousseau, Victor Climat, Environnement, Couplages et Incertitudes Toulouse (CECI) Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Université Paul Sabatier - Toulouse III Emilia Sanchez-Gomez Rym Msadek 2020-11-17 https://theses.hal.science/tel-03667341 https://theses.hal.science/tel-03667341/document https://theses.hal.science/tel-03667341/file/2020TOU30318b.pdf fr fre HAL CCSD NNT: 2020TOU30318 tel-03667341 https://theses.hal.science/tel-03667341 https://theses.hal.science/tel-03667341/document https://theses.hal.science/tel-03667341/file/2020TOU30318b.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-03667341 Océan, Atmosphère. Université Paul Sabatier - Toulouse III, 2020. Français. ⟨NNT : 2020TOU30318⟩ Air-sea interactions Gulf Stream SST fronts Synoptic anomalies Storm tracks Interactions océan-atmosphère Fronts de SST Anomalies synoptiques Routes dépressionnaires [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/doctoralThesis Theses 2020 ftinsu 2023-06-05T20:36:10Z This thesis aims at understanding the role of sea surface temperature (SST) fronts on air-sea interactions in the Gulf Stream region. We study the local response of the atmosphere to the SST mesoscale variability, not only within the marine atmospheric boundary layer (MABL), but also in the free troposphere. We also evaluate the impact of SST fronts beyond the Gulf Stream region, in particular on the North Atlantic atmospheric circulation and climate over Europe. We focus on the winter season (December-January-February), when air-sea contrasts and hence air-sea exchanges are the strongest. On this purpose, we perform and analyze numerical experiments, using the global atmospheric model ARPEGEv6 forced by observed daily SSTs at high resolution (1/4°). In the first part of this thesis we investigate two major MABL mechanisms responsible for the atmospheric response to the SST fronts over the Gulf Stream region. These mechanisms are the vertical mixing and the pressure adjustment mechanisms. Two sets of atmospheric simulations performed with two ARPEGEv6 configurations are considered: a low-resolution version (140 km) and a high resolution version (50 km). We analyze the response of the divergence of the near surface wind, because this is one of the main imprint of the MABL response to the SST front. While in most of previous studies monthly averages were used to study the response of the wind divergence to the SST fronts, our results highlight the key role of synoptic atmospheric perturbations on modulating the contribution of these two MABL mechanisms and hence on shaping the time-mean divergence of near surface wind. We show in particular that most of the winter-mean wind divergence simulated above the Gulf Stream region can be explained by the cyclonic anomalous circulation that occurs during extreme conditions of heat flux exchanges. The comparison of the results obtained with the high and low resolution versions of the atmospheric model shows that the impact of model resolution is small compared to internal ... Doctoral or Postdoctoral Thesis North Atlantic Institut national des sciences de l'Univers: HAL-INSU |
institution |
Open Polar |
collection |
Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
French |
topic |
Air-sea interactions Gulf Stream SST fronts Synoptic anomalies Storm tracks Interactions océan-atmosphère Fronts de SST Anomalies synoptiques Routes dépressionnaires [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
spellingShingle |
Air-sea interactions Gulf Stream SST fronts Synoptic anomalies Storm tracks Interactions océan-atmosphère Fronts de SST Anomalies synoptiques Routes dépressionnaires [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere Rousseau, Victor Air-sea interactions over the Gulf Stream region : benefits of higher-resolution in the representation of the physical mechanisms and climate impacts |
topic_facet |
Air-sea interactions Gulf Stream SST fronts Synoptic anomalies Storm tracks Interactions océan-atmosphère Fronts de SST Anomalies synoptiques Routes dépressionnaires [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
description |
This thesis aims at understanding the role of sea surface temperature (SST) fronts on air-sea interactions in the Gulf Stream region. We study the local response of the atmosphere to the SST mesoscale variability, not only within the marine atmospheric boundary layer (MABL), but also in the free troposphere. We also evaluate the impact of SST fronts beyond the Gulf Stream region, in particular on the North Atlantic atmospheric circulation and climate over Europe. We focus on the winter season (December-January-February), when air-sea contrasts and hence air-sea exchanges are the strongest. On this purpose, we perform and analyze numerical experiments, using the global atmospheric model ARPEGEv6 forced by observed daily SSTs at high resolution (1/4°). In the first part of this thesis we investigate two major MABL mechanisms responsible for the atmospheric response to the SST fronts over the Gulf Stream region. These mechanisms are the vertical mixing and the pressure adjustment mechanisms. Two sets of atmospheric simulations performed with two ARPEGEv6 configurations are considered: a low-resolution version (140 km) and a high resolution version (50 km). We analyze the response of the divergence of the near surface wind, because this is one of the main imprint of the MABL response to the SST front. While in most of previous studies monthly averages were used to study the response of the wind divergence to the SST fronts, our results highlight the key role of synoptic atmospheric perturbations on modulating the contribution of these two MABL mechanisms and hence on shaping the time-mean divergence of near surface wind. We show in particular that most of the winter-mean wind divergence simulated above the Gulf Stream region can be explained by the cyclonic anomalous circulation that occurs during extreme conditions of heat flux exchanges. The comparison of the results obtained with the high and low resolution versions of the atmospheric model shows that the impact of model resolution is small compared to internal ... |
author2 |
Climat, Environnement, Couplages et Incertitudes Toulouse (CECI) Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Université Paul Sabatier - Toulouse III Emilia Sanchez-Gomez Rym Msadek |
format |
Doctoral or Postdoctoral Thesis |
author |
Rousseau, Victor |
author_facet |
Rousseau, Victor |
author_sort |
Rousseau, Victor |
title |
Air-sea interactions over the Gulf Stream region : benefits of higher-resolution in the representation of the physical mechanisms and climate impacts |
title_short |
Air-sea interactions over the Gulf Stream region : benefits of higher-resolution in the representation of the physical mechanisms and climate impacts |
title_full |
Air-sea interactions over the Gulf Stream region : benefits of higher-resolution in the representation of the physical mechanisms and climate impacts |
title_fullStr |
Air-sea interactions over the Gulf Stream region : benefits of higher-resolution in the representation of the physical mechanisms and climate impacts |
title_full_unstemmed |
Air-sea interactions over the Gulf Stream region : benefits of higher-resolution in the representation of the physical mechanisms and climate impacts |
title_sort |
air-sea interactions over the gulf stream region : benefits of higher-resolution in the representation of the physical mechanisms and climate impacts |
publisher |
HAL CCSD |
publishDate |
2020 |
url |
https://theses.hal.science/tel-03667341 https://theses.hal.science/tel-03667341/document https://theses.hal.science/tel-03667341/file/2020TOU30318b.pdf |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
https://theses.hal.science/tel-03667341 Océan, Atmosphère. Université Paul Sabatier - Toulouse III, 2020. Français. ⟨NNT : 2020TOU30318⟩ |
op_relation |
NNT: 2020TOU30318 tel-03667341 https://theses.hal.science/tel-03667341 https://theses.hal.science/tel-03667341/document https://theses.hal.science/tel-03667341/file/2020TOU30318b.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1769008056064016384 |