On the Pathways of the Return Flow of the Meridional Overturning Circulation in the Tropical Atlantic
A numerical model of the tropical Atlantic ocean is used to investigate the upper layer pathways of the Meridional Overturning Circulation (MOC) in the tropical Atlantic. The main focus of this thesis is on those parts of the tropical circulation that are thought to be important for the MOC return f...
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ftdtic:ADA408850 2023-05-15T17:32:38+02:00 On the Pathways of the Return Flow of the Meridional Overturning Circulation in the Tropical Atlantic Jochum, Markus MASSACHUSETTS INST OF TECH CAMBRIDGE 2002-06 text/html http://www.dtic.mil/docs/citations/ADA408850 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA408850 en eng http://www.dtic.mil/docs/citations/ADA408850 APPROVED FOR PUBLIC RELEASE DTIC AND NTIS Physical and Dynamic Oceanography Fluid Mechanics *OCEAN CURRENTS *FLOW MATHEMATICAL MODELS THESES EDDIES(FLUID MECHANICS) TROPICAL REGIONS EULER EQUATIONS ATLANTIC OCEAN THERMOCLINES ROSSBY WAVES EULERIAN MEAN FLOW MERIDIONAL OVERTURNING CIRCULATION Text 2002 ftdtic 2016-02-21T04:12:59Z A numerical model of the tropical Atlantic ocean is used to investigate the upper layer pathways of the Meridional Overturning Circulation (MOC) in the tropical Atlantic. The main focus of this thesis is on those parts of the tropical circulation that are thought to be important for the MOC return flow, but whose dynamics have not been understood yet. It is shown how the particular structure of the tropical gyre and the MOO act to inhibit the flow of North Atlantic water into the equatorial thermocline. As a result, the upper layers of the tropical Atlantic are mainly fed by water from the South Atlantic. The processes that carry the South Atlantic water across the tropical Atlantic into the North Atlantic as part of the MOO are described here, and three processes that were hitherto not understood are explained as follows: The North Brazil Current rings are created as the result of the reflection of Rossby waves at the South American coast. These Rossby waves are generated by the barotropically unstable North Equatorial Countercurrent. The deep structure of the rings can be explained by merger of the wave's anticyclones with the deeper intermediate eddies that are generated as the intermediate western boundary current crosses the equator. The bands of strong zonal velocity in intermediate depths along the equator have hitherto been explained as intermediate currents. Here, an alternative interpretation of the observations is offered: The Eulerian mean flow along the equator is negligible and the observations are the signature of strong seasonal Rossby waves. The previous interpretation of the observations can then be explained as aliasing of the tropical wave field. The Tsuchyia Jets are driven by the Eliassen-Palm flux of the tropical instability waves. The equatorial current system with its strong shears is unstable and generates tropical instability waves. Prepared in cooperation with Woods Hole Oceanographic Institution, MA. Text North Atlantic Defense Technical Information Center: DTIC Technical Reports database |
institution |
Open Polar |
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Defense Technical Information Center: DTIC Technical Reports database |
op_collection_id |
ftdtic |
language |
English |
topic |
Physical and Dynamic Oceanography Fluid Mechanics *OCEAN CURRENTS *FLOW MATHEMATICAL MODELS THESES EDDIES(FLUID MECHANICS) TROPICAL REGIONS EULER EQUATIONS ATLANTIC OCEAN THERMOCLINES ROSSBY WAVES EULERIAN MEAN FLOW MERIDIONAL OVERTURNING CIRCULATION |
spellingShingle |
Physical and Dynamic Oceanography Fluid Mechanics *OCEAN CURRENTS *FLOW MATHEMATICAL MODELS THESES EDDIES(FLUID MECHANICS) TROPICAL REGIONS EULER EQUATIONS ATLANTIC OCEAN THERMOCLINES ROSSBY WAVES EULERIAN MEAN FLOW MERIDIONAL OVERTURNING CIRCULATION Jochum, Markus On the Pathways of the Return Flow of the Meridional Overturning Circulation in the Tropical Atlantic |
topic_facet |
Physical and Dynamic Oceanography Fluid Mechanics *OCEAN CURRENTS *FLOW MATHEMATICAL MODELS THESES EDDIES(FLUID MECHANICS) TROPICAL REGIONS EULER EQUATIONS ATLANTIC OCEAN THERMOCLINES ROSSBY WAVES EULERIAN MEAN FLOW MERIDIONAL OVERTURNING CIRCULATION |
description |
A numerical model of the tropical Atlantic ocean is used to investigate the upper layer pathways of the Meridional Overturning Circulation (MOC) in the tropical Atlantic. The main focus of this thesis is on those parts of the tropical circulation that are thought to be important for the MOC return flow, but whose dynamics have not been understood yet. It is shown how the particular structure of the tropical gyre and the MOO act to inhibit the flow of North Atlantic water into the equatorial thermocline. As a result, the upper layers of the tropical Atlantic are mainly fed by water from the South Atlantic. The processes that carry the South Atlantic water across the tropical Atlantic into the North Atlantic as part of the MOO are described here, and three processes that were hitherto not understood are explained as follows: The North Brazil Current rings are created as the result of the reflection of Rossby waves at the South American coast. These Rossby waves are generated by the barotropically unstable North Equatorial Countercurrent. The deep structure of the rings can be explained by merger of the wave's anticyclones with the deeper intermediate eddies that are generated as the intermediate western boundary current crosses the equator. The bands of strong zonal velocity in intermediate depths along the equator have hitherto been explained as intermediate currents. Here, an alternative interpretation of the observations is offered: The Eulerian mean flow along the equator is negligible and the observations are the signature of strong seasonal Rossby waves. The previous interpretation of the observations can then be explained as aliasing of the tropical wave field. The Tsuchyia Jets are driven by the Eliassen-Palm flux of the tropical instability waves. The equatorial current system with its strong shears is unstable and generates tropical instability waves. Prepared in cooperation with Woods Hole Oceanographic Institution, MA. |
author2 |
MASSACHUSETTS INST OF TECH CAMBRIDGE |
format |
Text |
author |
Jochum, Markus |
author_facet |
Jochum, Markus |
author_sort |
Jochum, Markus |
title |
On the Pathways of the Return Flow of the Meridional Overturning Circulation in the Tropical Atlantic |
title_short |
On the Pathways of the Return Flow of the Meridional Overturning Circulation in the Tropical Atlantic |
title_full |
On the Pathways of the Return Flow of the Meridional Overturning Circulation in the Tropical Atlantic |
title_fullStr |
On the Pathways of the Return Flow of the Meridional Overturning Circulation in the Tropical Atlantic |
title_full_unstemmed |
On the Pathways of the Return Flow of the Meridional Overturning Circulation in the Tropical Atlantic |
title_sort |
on the pathways of the return flow of the meridional overturning circulation in the tropical atlantic |
publishDate |
2002 |
url |
http://www.dtic.mil/docs/citations/ADA408850 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA408850 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
DTIC AND NTIS |
op_relation |
http://www.dtic.mil/docs/citations/ADA408850 |
op_rights |
APPROVED FOR PUBLIC RELEASE |
_version_ |
1766130834846253056 |