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| Feucher, Charlene; Maze, Guillaume; Mercier, Herle. |
| In the North Atlantic subtropical gyre, the oceanic vertical structure of density is characterized by a region of rapid increase with depth. This layer is called the permanent pycnocline. The pycnocline is the transition layer between light, low-latitude, surface water masses which are ventilated every winter when penetrated locally by the mixed layer and dense, deeper water masses whose properties are set in the high latitudes. Assessing the structure and variability of the permanent pycnocline is of a major interest in the under- standing of the climate system because the pycnocline embeds the warm water sphere and most of the wind-forced horizontal circulation. We characterized the large scale structure of the permanent pycnocline with in-situ data... |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00257/36818/35450.pdf |
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| Maze, Guillaume; Feucher, Charlene; Mercier, Herle; Dewar, William. |
| In a changing climate, a description of the permanent pycnocline, which is globally coherent and independant from any thermohaline properties, is required in order to provide a reference state for the identification of the warm water sphere variability. Using a recently developped pattern recognition method applied to stratification profiles from Argo in situ data, this study presents such a reference state for the subtropical latitudes and the 2000-2015 period. With this method, a mode water core is recognised as a stratification minimum that is, possibly temporarely, trapped below the seasonal pycnocline. The permanent pycnocline is recognised as the stratification maximum localised below that mode water core. First, we will show that away from... |
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| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00435/54641/56060.pdf |
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| Feucher, Charlene; Maze, Guillaume; Mercier, Herle. |
| In the north Atlantic subtropical gyre, the oceanic vertical structure of density is characterized by a region of rapid increase with depth. This layer is called the permanent pycnocline. The permanent pycnocline is found below a surface mode water ,which are ventilated every winter when penetrated locally by the mixed layer. Assessing the structure and variability of the permanent pycnocline is of a major interest in the understanding of the climate system because the pycnocline layer delimits important heat and anthropogenic reservoir. Moreover, the heat content structure translate into changes in the large scale stratification feature, such as the permanent pycnocline. We developed a new objective algorithm for the characterization of the large scale... |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00318/42870/42351.pdf |
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| Feucher, Charlene; Maze, Guillaume; Mercier, Herle. |
| A new Objective Algorithm for the Characterization of the permanent Pycnocline (OACP) in subtropical gyres is proposed. OAC-P is based on a pragmatic analysis of vertical density gradient features to identify the permanent pycnocline: OAC-P identifies the permanent pycnocline as the stratified layer found below surface mode waters. OAC-P provides the permanent pycnocline depth, unequivocally associated with a local maximum in the stratification, and top and bottom thicknesses, associated with upward and downward decreases in stratification. OAC-P uses half Gaussian curves as asymmetric non-linear analytical models of the stratification peak. It is the first time that an algorithm is proposed to characterize objectively the permanent pycnocline for a region... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00326/43710/44712.pdf |
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| Feucher, Charlene; Maze, Guillaume; Mercier, Herle. |
| A global reference state of the subtropical mode waters and permanent pycnoclines properties for the 2000‐2015 period is presented. The climatology is obtained from a pattern recognition algorithm applied to stratification profiles from the Argo global array. The stratification features are identified as permanent upper ocean pycnostad and pycnocline even when the seasonal pycnocline is developed. The climatology shows that both Northern Hemisphere subtropical gyres have a qualitatively very similar stratification structure. The permanent pycnocline in the North Atlantic and North Pacific show two deep centers colocated with thick subtropical and subpolar mode waters. These centers coincide with modes in the density and stratification space. These deep... |
| Tipo: Text |
Palavras-chave: Subtropical gyre; Pycnocline; Argo; Global ocean; Stratification. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00480/59176/61817.pdf |
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| Feucher, Charlene; Maze, Guillaume; Mercier, Herle. |
| In the north Atlantic subtropical gyre, the oceanic vertical structure of density is characterized by a region of rapid increase with depth. This layer is called the permanent pycnocline because this density feature is observed throughout the year. The pycnocline is the transition layer between light, low-latitude, surface water masses which are ventilated every winter when penetrated locally by the mixed layer and dense, deeper water masses whose properties are set in the high latitudes and circulate equatorward. In-situ data from the Argo array provide temperature/salinity profiles allowing the characterization in space and time of the permanent pycnocline. We thus developed a new method to characterize its depth, thickness and thermohaline... |
| Tipo: Text |
Palavras-chave: Argo; Quality Control; Pattern; Clustering; North Atlantic; Subtropical gyre; Stratification. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00242/35315/33838.pdf |
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