{"id":{"repo_id":"woods-hole","oai_identifier":"oai:darchive.mblwhoilibrary.org:1912/26126"},"canonical_url":"https://search.dev.ndltd.org/etd/woods-hole/oai:darchive.mblwhoilibrary.org:1912/26126","repository":{"repo_id":"woods-hole","name":"Woods Hole Oceanographic Institute","base_url":"https://darchive.mblwhoilibrary.org/server/oai/request"},"display":{"title":"Residual overturning circulation and its connection to Southern Ocean dynamics","abstract":"Over the last 20 years, our understanding of the meridional overturning circulation has improved, but primarily in a two-dimensional, zonally-averaged framework. In this thesis, I have pushed beyond this simplification and shown that the additional complexity of meanders, storm tracks, and other zonal asymmetries is necessary to reproduce the lowest-order behavior of the overturning circulation. First I examined the role of basin width for determining whether the Atlantic or Pacific oceans experience deep convection. I used a two layered model and a rectangular single-basin model to show that the basin width, in combination with scalings for the overturning circulation make the overturning relatively weaker in the wider basin, priming it for a convection shut down. In addition to this large-scale work, I have examined Southern Ocean-like meanders using a hierarchy of idealized models to understand the role of bottom topography in determining how the large-scale circulation responds to climate change scenarios. These are useful because they preserve the lowest-order behavior, while remaining simple enough to understand. I tested the response of the stratification and transport in the Southern Ocean to changes in wind using a highly-idealized two-layer quasi-geostrophic model. In addition to showing that meanders are necessary to reproduce the behavior of the Southern Ocean, I found that strong winds concentrate the baroclinic and barotropic instabilities downstream of the bottom topography and weaken the instabilities elsewhere due to a form-drag process. With weak winds, however, the system is essentially symmetric in longitude, like a flat-bottomed ocean. This result is consistent with observations of elevated turbulence downstream of major topography in the Southern Ocean. My next study investigated a more realistic Southern Ocean-like channel, with and without bottom topography, and examined the three-dimensional circulation in order to understand where vertical transport occurs and develop a picture of the pathways taken by each individual water parcel. I found that the vertical transport happens in very isolated locations, just downstream of topography. Finally, I added a biogeochemical model to my simulations and found that carbon fluxes are enhanced near topography, again highlighting the role of zonal asymmetries.","abstract_html":"Over the last 20 years, our understanding of the meridional overturning circulation has improved, but primarily in a two-dimensional, zonally-averaged framework. In this thesis, I have pushed beyond this simplification and shown that the additional complexity of meanders, storm tracks, and other zonal asymmetries is necessary to reproduce the lowest-order behavior of the overturning circulation. First I examined the role of basin width for determining whether the Atlantic or Pacific oceans experience deep convection. I used a two layered model and a rectangular single-basin model to show that the basin width, in combination with scalings for the overturning circulation make the overturning relatively weaker in the wider basin, priming it for a convection shut down. In addition to this large-scale work, I have examined Southern Ocean-like meanders using a hierarchy of idealized models to understand the role of bottom topography in determining how the large-scale circulation responds to climate change scenarios. These are useful because they preserve the lowest-order behavior, while remaining simple enough to understand. I tested the response of the stratification and transport in the Southern Ocean to changes in wind using a highly-idealized two-layer quasi-geostrophic model. In addition to showing that meanders are necessary to reproduce the behavior of the Southern Ocean, I found that strong winds concentrate the baroclinic and barotropic instabilities downstream of the bottom topography and weaken the instabilities elsewhere due to a form-drag process. With weak winds, however, the system is essentially symmetric in longitude, like a flat-bottomed ocean. This result is consistent with observations of elevated turbulence downstream of major topography in the Southern Ocean. My next study investigated a more realistic Southern Ocean-like channel, with and without bottom topography, and examined the three-dimensional circulation in order to understand where vertical transport occurs and develop a picture of the pathways taken by each individual water parcel. I found that the vertical transport happens in very isolated locations, just downstream of topography. Finally, I added a biogeochemical model to my simulations and found that carbon fluxes are enhanced near topography, again highlighting the role of zonal asymmetries.","abstract_has_math":false,"creators":["Youngs, Madeleine K."],"institution":"Massachusetts Institute of Technology and Woods Hole Oceanographic Institution","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020-09","date_published":"2020-09","updated_at":"2026-07-27T22:05:21Z","subjects":[],"languages":["en_US"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier.doi","label":"DOI","values":["10.1575/1912/26126"],"render_values":[{"text":"10.1575/1912/26126","href":"https://doi.org/10.1575/1912/26126","code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/1912/26126","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Youngs, Madeleine K."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2020-08-27T14:34:14Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2020-08-27T14:34:14Z"]},{"key":"dc:date.issued","label":"Date","values":["2020-09"]},{"key":"dc:publisher","label":"Institution","values":["Massachusetts Institute of Technology and Woods Hole Oceanographic Institution"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en_US"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.doi","label":"DOI","values":["10.1575/1912/26126"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/1912/26126"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2020."]},{"key":"dc:description.abstract","label":"Abstract","values":["Over the last 20 years, our understanding of the meridional overturning circulation has improved, but primarily in a two-dimensional, zonally-averaged framework. In this thesis, I have pushed beyond this simplification and shown that the additional complexity of meanders, storm tracks, and other zonal asymmetries is necessary to reproduce the lowest-order behavior of the overturning circulation. First I examined the role of basin width for determining whether the Atlantic or Pacific oceans experience deep convection. I used a two layered model and a rectangular single-basin model to show that the basin width, in combination with scalings for the overturning circulation make the overturning relatively weaker in the wider basin, priming it for a convection shut down. In addition to this large-scale work, I have examined Southern Ocean-like meanders using a hierarchy of idealized models to understand the role of bottom topography in determining how the large-scale circulation responds to climate change scenarios. These are useful because they preserve the lowest-order behavior, while remaining simple enough to understand. I tested the response of the stratification and transport in the Southern Ocean to changes in wind using a highly-idealized two-layer quasi-geostrophic model. In addition to showing that meanders are necessary to reproduce the behavior of the Southern Ocean, I found that strong winds concentrate the baroclinic and barotropic instabilities downstream of the bottom topography and weaken the instabilities elsewhere due to a form-drag process. With weak winds, however, the system is essentially symmetric in longitude, like a flat-bottomed ocean. This result is consistent with observations of elevated turbulence downstream of major topography in the Southern Ocean. My next study investigated a more realistic Southern Ocean-like channel, with and without bottom topography, and examined the three-dimensional circulation in order to understand where vertical transport occurs and develop a picture of the pathways taken by each individual water parcel. I found that the vertical transport happens in very isolated locations, just downstream of topography. Finally, I added a biogeochemical model to my simulations and found that carbon fluxes are enhanced near topography, again highlighting the role of zonal asymmetries."]},{"key":"dc:title","label":"Title","values":["Residual overturning circulation and its connection to Southern Ocean dynamics"]}]}],"canonical_facts":{"dc:creator":["Youngs, Madeleine K."],"dc:date.accessioned":["2020-08-27T14:34:14Z"],"dc:date.available":["2020-08-27T14:34:14Z"],"dc:date.issued":["2020-09"],"dc:description":["Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2020."],"dc:description.abstract":["Over the last 20 years, our understanding of the meridional overturning circulation has improved, but primarily in a two-dimensional, zonally-averaged framework. In this thesis, I have pushed beyond this simplification and shown that the additional complexity of meanders, storm tracks, and other zonal asymmetries is necessary to reproduce the lowest-order behavior of the overturning circulation. First I examined the role of basin width for determining whether the Atlantic or Pacific oceans experience deep convection. I used a two layered model and a rectangular single-basin model to show that the basin width, in combination with scalings for the overturning circulation make the overturning relatively weaker in the wider basin, priming it for a convection shut down. In addition to this large-scale work, I have examined Southern Ocean-like meanders using a hierarchy of idealized models to understand the role of bottom topography in determining how the large-scale circulation responds to climate change scenarios. These are useful because they preserve the lowest-order behavior, while remaining simple enough to understand. I tested the response of the stratification and transport in the Southern Ocean to changes in wind using a highly-idealized two-layer quasi-geostrophic model. In addition to showing that meanders are necessary to reproduce the behavior of the Southern Ocean, I found that strong winds concentrate the baroclinic and barotropic instabilities downstream of the bottom topography and weaken the instabilities elsewhere due to a form-drag process. With weak winds, however, the system is essentially symmetric in longitude, like a flat-bottomed ocean. This result is consistent with observations of elevated turbulence downstream of major topography in the Southern Ocean. My next study investigated a more realistic Southern Ocean-like channel, with and without bottom topography, and examined the three-dimensional circulation in order to understand where vertical transport occurs and develop a picture of the pathways taken by each individual water parcel. I found that the vertical transport happens in very isolated locations, just downstream of topography. Finally, I added a biogeochemical model to my simulations and found that carbon fluxes are enhanced near topography, again highlighting the role of zonal asymmetries."],"dc:identifier.doi":["10.1575/1912/26126"],"dc:identifier.uri":["https://hdl.handle.net/1912/26126"],"dc:language.iso":["en_US"],"dc:publisher":["Massachusetts Institute of Technology and Woods Hole Oceanographic Institution"],"dc:title":["Residual overturning circulation and its connection to Southern Ocean dynamics"],"dc:type":["Thesis"]},"updated_at":"2026-07-27T22:05:21Z"}