Modelling large scale ocean circulation : the role of mixing location and meridional pressure gradients for the Atlantic overturning dynamics
Due to its relevance for global climate, the realistic representation of the Atlantic meridional overturning circulation (AMOC) in ocean models is a key task. In recent years, two paradigms have evolved around what are its driving mechanisms: diapycnal mixing and Southern Ocean winds. This work aims...
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ftubpotsdam:oai:kobv.de-opus4-uni-potsdam:244 2023-05-15T17:36:39+02:00 Modelling large scale ocean circulation : the role of mixing location and meridional pressure gradients for the Atlantic overturning dynamics Modellierung grossräumiger Ozeanzirkulation :die Rolle inhomoger verteilter Vermischung und meridionaler Druckgradienten für die Atlantische Tiefenzirkulation Griesel, Alexa 2005-05-04 application/x-gzip application/pdf https://publishup.uni-potsdam.de/opus4-ubp/frontdoor/index/index/docId/244 https://nbn-resolving.org/urn:nbn:de:kobv:517-opus-2609 https://publishup.uni-potsdam.de/opus4-ubp/files/244/container.tgz https://publishup.uni-potsdam.de/opus4-ubp/files/244/giesel.pdf eng eng https://publishup.uni-potsdam.de/opus4-ubp/frontdoor/index/index/docId/244 urn:nbn:de:kobv:517-opus-2609 https://nbn-resolving.org/urn:nbn:de:kobv:517-opus-2609 https://publishup.uni-potsdam.de/opus4-ubp/files/244/container.tgz https://publishup.uni-potsdam.de/opus4-ubp/files/244/giesel.pdf info:eu-repo/semantics/openAccess Thermohaline Zirkulation Parametrisierung Vermischung Atlantischer Ozean ddc:530 Institut für Physik und Astronomie doctoralthesis doc-type:doctoralThesis 2005 ftubpotsdam 2022-07-28T20:34:37Z Due to its relevance for global climate, the realistic representation of the Atlantic meridional overturning circulation (AMOC) in ocean models is a key task. In recent years, two paradigms have evolved around what are its driving mechanisms: diapycnal mixing and Southern Ocean winds. This work aims at clarifying what sets the strength of the Atlantic overturning components in an ocean general circulation model and discusses the role of spatially inhomogeneous mixing, numerical diffusion and winds. Furthermore, the relation of the AMOC with a key quantity, the meridional pressure difference is analyzed. Due to the application of a very low diffusive tracer advection scheme, a realistic Atlantic overturning circulation can be obtained that is purely wind driven. On top of the winddriven circulation, changes of density gradients are caused by increasing the parameterized eddy diffusion in the North Atlantic and Southern Ocean. The linear relation between the maximum of the Atlantic overturning and the meridional pressure difference found in previous studies is confirmed and it is shown to be due to one significant pressure gradient between the average pressure over high latitude deep water formation regions and a relatively uniform pressure between 30°N and 30°S, which can directly be related to a zonal flow through geostrophy. Under constant Southern Ocean windstress forcing, a South Atlantic outflow in the range of 6-16 Sv is obtained for a large variety of experiments. Overall, the circulation is winddriven but its strength not uniquely determined by the Southern Ocean windstress. The scaling of the Atlantic overturning components is linear with the background vertical diffusivity, not confirming the 2/3 power law for one-hemisphere models without wind forcing. The pycnocline depth is constant in the coarse resolution model with large vertical grid extends. It suggests the ocean model operates like the Stommel box model with a linear relation of the pressure difference and fixed vertical scale for the volume ... Doctoral or Postdoctoral Thesis North Atlantic Southern Ocean University of Potsdam: publish.UP Southern Ocean |
institution |
Open Polar |
collection |
University of Potsdam: publish.UP |
op_collection_id |
ftubpotsdam |
language |
English |
topic |
Thermohaline Zirkulation Parametrisierung Vermischung Atlantischer Ozean ddc:530 Institut für Physik und Astronomie |
spellingShingle |
Thermohaline Zirkulation Parametrisierung Vermischung Atlantischer Ozean ddc:530 Institut für Physik und Astronomie Griesel, Alexa Modelling large scale ocean circulation : the role of mixing location and meridional pressure gradients for the Atlantic overturning dynamics |
topic_facet |
Thermohaline Zirkulation Parametrisierung Vermischung Atlantischer Ozean ddc:530 Institut für Physik und Astronomie |
description |
Due to its relevance for global climate, the realistic representation of the Atlantic meridional overturning circulation (AMOC) in ocean models is a key task. In recent years, two paradigms have evolved around what are its driving mechanisms: diapycnal mixing and Southern Ocean winds. This work aims at clarifying what sets the strength of the Atlantic overturning components in an ocean general circulation model and discusses the role of spatially inhomogeneous mixing, numerical diffusion and winds. Furthermore, the relation of the AMOC with a key quantity, the meridional pressure difference is analyzed. Due to the application of a very low diffusive tracer advection scheme, a realistic Atlantic overturning circulation can be obtained that is purely wind driven. On top of the winddriven circulation, changes of density gradients are caused by increasing the parameterized eddy diffusion in the North Atlantic and Southern Ocean. The linear relation between the maximum of the Atlantic overturning and the meridional pressure difference found in previous studies is confirmed and it is shown to be due to one significant pressure gradient between the average pressure over high latitude deep water formation regions and a relatively uniform pressure between 30°N and 30°S, which can directly be related to a zonal flow through geostrophy. Under constant Southern Ocean windstress forcing, a South Atlantic outflow in the range of 6-16 Sv is obtained for a large variety of experiments. Overall, the circulation is winddriven but its strength not uniquely determined by the Southern Ocean windstress. The scaling of the Atlantic overturning components is linear with the background vertical diffusivity, not confirming the 2/3 power law for one-hemisphere models without wind forcing. The pycnocline depth is constant in the coarse resolution model with large vertical grid extends. It suggests the ocean model operates like the Stommel box model with a linear relation of the pressure difference and fixed vertical scale for the volume ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Griesel, Alexa |
author_facet |
Griesel, Alexa |
author_sort |
Griesel, Alexa |
title |
Modelling large scale ocean circulation : the role of mixing location and meridional pressure gradients for the Atlantic overturning dynamics |
title_short |
Modelling large scale ocean circulation : the role of mixing location and meridional pressure gradients for the Atlantic overturning dynamics |
title_full |
Modelling large scale ocean circulation : the role of mixing location and meridional pressure gradients for the Atlantic overturning dynamics |
title_fullStr |
Modelling large scale ocean circulation : the role of mixing location and meridional pressure gradients for the Atlantic overturning dynamics |
title_full_unstemmed |
Modelling large scale ocean circulation : the role of mixing location and meridional pressure gradients for the Atlantic overturning dynamics |
title_sort |
modelling large scale ocean circulation : the role of mixing location and meridional pressure gradients for the atlantic overturning dynamics |
publishDate |
2005 |
url |
https://publishup.uni-potsdam.de/opus4-ubp/frontdoor/index/index/docId/244 https://nbn-resolving.org/urn:nbn:de:kobv:517-opus-2609 https://publishup.uni-potsdam.de/opus4-ubp/files/244/container.tgz https://publishup.uni-potsdam.de/opus4-ubp/files/244/giesel.pdf |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
North Atlantic Southern Ocean |
genre_facet |
North Atlantic Southern Ocean |
op_relation |
https://publishup.uni-potsdam.de/opus4-ubp/frontdoor/index/index/docId/244 urn:nbn:de:kobv:517-opus-2609 https://nbn-resolving.org/urn:nbn:de:kobv:517-opus-2609 https://publishup.uni-potsdam.de/opus4-ubp/files/244/container.tgz https://publishup.uni-potsdam.de/opus4-ubp/files/244/giesel.pdf |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1766136219142455296 |