Diapycnal mixing in the subpolar North Atlantic
Model simulations of climate change and global overturning circulation are quite sensitive to the strength and distribution of mixing. However, the field observations are only sparsely available. The strength of diapycnal mixing was estimated from more than 700 profiles of hydrographic and velocity...
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Universität Bremen
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Online Access: | https://media.suub.uni-bremen.de/handle/elib/546 https://nbn-resolving.org/urn:nbn:de:gbv:46-00103429-11 |
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ftsubbremen:oai:media.suub.uni-bremen.de:Publications/elib/546 2023-05-15T16:00:41+02:00 Diapycnal mixing in the subpolar North Atlantic Diapyknische Vermischung im Subpolaren Nordatlantik Li, Mingming Rhein, Monika Greatbatch, Richard J. 2013-10-16 application/pdf https://media.suub.uni-bremen.de/handle/elib/546 https://nbn-resolving.org/urn:nbn:de:gbv:46-00103429-11 eng eng Universität Bremen FB1 Physik/Elektrotechnik https://media.suub.uni-bremen.de/handle/elib/546 urn:nbn:de:gbv:46-00103429-11 info:eu-repo/semantics/openAccess diapycnal mixing diffusivity dissipation finescale parameterization 550 550 Earth sciences and geology ddc:550 Dissertation doctoralThesis 2013 ftsubbremen 2022-11-09T07:09:23Z Model simulations of climate change and global overturning circulation are quite sensitive to the strength and distribution of mixing. However, the field observations are only sparsely available. The strength of diapycnal mixing was estimated from more than 700 profiles of hydrographic and velocity measurements in the subpolar North Atlantic (SPNA). These measurements were collected during hydrographic surveys from 2003 to 2011, ranging from 40 N to 62 N in latitude. Furthermore, 28 Micro-scale structure profiles were collected at 7 stations over the Mid-Atlantic Ridge and at the western boundary during the cruise in 2008, providing supplement of direct measurements and an agent to evaluate the overall estimation. Under the assumption of a steady state, spatial distribution and vertical structure of diapycnal diffusivity were mapped in this area. The inferred diffusivity is generally elevated compared to the background diffusivity in the open ocean and shows large variability in the SPNA. diffusivity of at least one magnitude larger can be seen nearly in the whole area several hundread of meters within seafloor. Strong mixing at mid-depth of one to two orders larger than the background value are found at western boundary, over Mid-Atlantic ridge and in the pathway of North Atlantic Current and deep currents. The possible connections between enhanced mixing and several environmental parameters including seafloor roughness, geostrophic currents and meso-scale eddies are analysed. Conversions between components of the North Atlantic Deep Water associated with mixing are estimated from vertical motion inferred from density field and turbulent diffusivity based on an advection-diffusion balance model. In vertical direction, averaged diffusivity is found to decrease with the height above seafloor within the deepest 1500 m and to be constant. A transformation of around 1.6 Sv from Gibbs Fracture Zone Water to overlying Labrador Sea water is derived; the transformation between lowest Denmark Strait Overflow Water to ... Doctoral or Postdoctoral Thesis Denmark Strait Labrador Sea north atlantic current North Atlantic Deep Water North Atlantic Media SuUB Bremen (Staats- und Universitätsbibliothek Bremen) Mid-Atlantic Ridge |
institution |
Open Polar |
collection |
Media SuUB Bremen (Staats- und Universitätsbibliothek Bremen) |
op_collection_id |
ftsubbremen |
language |
English |
topic |
diapycnal mixing diffusivity dissipation finescale parameterization 550 550 Earth sciences and geology ddc:550 |
spellingShingle |
diapycnal mixing diffusivity dissipation finescale parameterization 550 550 Earth sciences and geology ddc:550 Li, Mingming Diapycnal mixing in the subpolar North Atlantic |
topic_facet |
diapycnal mixing diffusivity dissipation finescale parameterization 550 550 Earth sciences and geology ddc:550 |
description |
Model simulations of climate change and global overturning circulation are quite sensitive to the strength and distribution of mixing. However, the field observations are only sparsely available. The strength of diapycnal mixing was estimated from more than 700 profiles of hydrographic and velocity measurements in the subpolar North Atlantic (SPNA). These measurements were collected during hydrographic surveys from 2003 to 2011, ranging from 40 N to 62 N in latitude. Furthermore, 28 Micro-scale structure profiles were collected at 7 stations over the Mid-Atlantic Ridge and at the western boundary during the cruise in 2008, providing supplement of direct measurements and an agent to evaluate the overall estimation. Under the assumption of a steady state, spatial distribution and vertical structure of diapycnal diffusivity were mapped in this area. The inferred diffusivity is generally elevated compared to the background diffusivity in the open ocean and shows large variability in the SPNA. diffusivity of at least one magnitude larger can be seen nearly in the whole area several hundread of meters within seafloor. Strong mixing at mid-depth of one to two orders larger than the background value are found at western boundary, over Mid-Atlantic ridge and in the pathway of North Atlantic Current and deep currents. The possible connections between enhanced mixing and several environmental parameters including seafloor roughness, geostrophic currents and meso-scale eddies are analysed. Conversions between components of the North Atlantic Deep Water associated with mixing are estimated from vertical motion inferred from density field and turbulent diffusivity based on an advection-diffusion balance model. In vertical direction, averaged diffusivity is found to decrease with the height above seafloor within the deepest 1500 m and to be constant. A transformation of around 1.6 Sv from Gibbs Fracture Zone Water to overlying Labrador Sea water is derived; the transformation between lowest Denmark Strait Overflow Water to ... |
author2 |
Rhein, Monika Greatbatch, Richard J. |
format |
Doctoral or Postdoctoral Thesis |
author |
Li, Mingming |
author_facet |
Li, Mingming |
author_sort |
Li, Mingming |
title |
Diapycnal mixing in the subpolar North Atlantic |
title_short |
Diapycnal mixing in the subpolar North Atlantic |
title_full |
Diapycnal mixing in the subpolar North Atlantic |
title_fullStr |
Diapycnal mixing in the subpolar North Atlantic |
title_full_unstemmed |
Diapycnal mixing in the subpolar North Atlantic |
title_sort |
diapycnal mixing in the subpolar north atlantic |
publisher |
Universität Bremen |
publishDate |
2013 |
url |
https://media.suub.uni-bremen.de/handle/elib/546 https://nbn-resolving.org/urn:nbn:de:gbv:46-00103429-11 |
geographic |
Mid-Atlantic Ridge |
geographic_facet |
Mid-Atlantic Ridge |
genre |
Denmark Strait Labrador Sea north atlantic current North Atlantic Deep Water North Atlantic |
genre_facet |
Denmark Strait Labrador Sea north atlantic current North Atlantic Deep Water North Atlantic |
op_relation |
https://media.suub.uni-bremen.de/handle/elib/546 urn:nbn:de:gbv:46-00103429-11 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1766396700606332928 |