Topographic Influence on Overflow Dynamics: Idealized Numerical Simulations and the Faroe Bank Channel Overflow
Properties of the North Atlantic Deep Water (NADW) depend on mixing that occurs in the Denmark Strait (DS) and the Faroe Bank Channel (FBC) overflow regions. How the sill's topography in those regions may affect mixing processes and downstream variability is thus investigated using a high-resol...
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ftolddominionuni:oai:digitalcommons.odu.edu:ccpo_pubs-1136 2023-05-15T16:00:38+02:00 Topographic Influence on Overflow Dynamics: Idealized Numerical Simulations and the Faroe Bank Channel Overflow Ezer, Tal 2006-01-01T08:00:00Z application/pdf https://digitalcommons.odu.edu/ccpo_pubs/127 https://digitalcommons.odu.edu/cgi/viewcontent.cgi?article=1136&context=ccpo_pubs unknown ODU Digital Commons https://digitalcommons.odu.edu/ccpo_pubs/127 https://digitalcommons.odu.edu/cgi/viewcontent.cgi?article=1136&context=ccpo_pubs CCPO Publications Boundary layer flow Channel flow Computer simulation Denmark Strait Flow Sensitivity analysis Steady flow Oceanography article 2006 ftolddominionuni 2021-03-02T18:08:41Z Properties of the North Atlantic Deep Water (NADW) depend on mixing that occurs in the Denmark Strait (DS) and the Faroe Bank Channel (FBC) overflow regions. How the sill's topography in those regions may affect mixing processes and downstream variability is thus investigated using a high-resolution terrain-following ocean model. Model results agree with observations that show enhanced mixing and entrainment downstream from the sill; however, mixing seems to occur over a longer distance downstream from the FBC sill and more abruptly downstream from the DS sill. Sensitivity experiments with various FBC sill widths demonstrate that the narrow sill is responsible for the enhanced mixing. The downstream flow variability, eddy propagation, and deep water properties are affected by sill width and background stratification. Similar to the laboratory overflow experiments of Cenedese et al. (2004), three distinct mixing regimes (characterized by the Froude number) are identified in the FBC simulations: a steady subcritical flow regime upstream from the sill, a supercritical wave-like flow regime downstream from the sill, and an irregular eddy-dominated regime farther away from the sill. Satellite altimeter data near the FBC show cyclonic anomalies propagating along the northern slope of the channel, resembling the surface eddies associated with the overflow variability in the model. A cross-channel circulation over the FBC sill, driven by frictional bottom boundary layers, resulted in convergence/divergence zones near the southern/northern slopes and pinching/spreading of isotherms across the channel, similar to the observation-based mechanism proposed by Johnson and Sanford (1992). Article in Journal/Newspaper Denmark Strait NADW North Atlantic Deep Water North Atlantic Old Dominion University: ODU Digital Commons Faroe Bank ENVELOPE(-8.667,-8.667,60.917,60.917) |
institution |
Open Polar |
collection |
Old Dominion University: ODU Digital Commons |
op_collection_id |
ftolddominionuni |
language |
unknown |
topic |
Boundary layer flow Channel flow Computer simulation Denmark Strait Flow Sensitivity analysis Steady flow Oceanography |
spellingShingle |
Boundary layer flow Channel flow Computer simulation Denmark Strait Flow Sensitivity analysis Steady flow Oceanography Ezer, Tal Topographic Influence on Overflow Dynamics: Idealized Numerical Simulations and the Faroe Bank Channel Overflow |
topic_facet |
Boundary layer flow Channel flow Computer simulation Denmark Strait Flow Sensitivity analysis Steady flow Oceanography |
description |
Properties of the North Atlantic Deep Water (NADW) depend on mixing that occurs in the Denmark Strait (DS) and the Faroe Bank Channel (FBC) overflow regions. How the sill's topography in those regions may affect mixing processes and downstream variability is thus investigated using a high-resolution terrain-following ocean model. Model results agree with observations that show enhanced mixing and entrainment downstream from the sill; however, mixing seems to occur over a longer distance downstream from the FBC sill and more abruptly downstream from the DS sill. Sensitivity experiments with various FBC sill widths demonstrate that the narrow sill is responsible for the enhanced mixing. The downstream flow variability, eddy propagation, and deep water properties are affected by sill width and background stratification. Similar to the laboratory overflow experiments of Cenedese et al. (2004), three distinct mixing regimes (characterized by the Froude number) are identified in the FBC simulations: a steady subcritical flow regime upstream from the sill, a supercritical wave-like flow regime downstream from the sill, and an irregular eddy-dominated regime farther away from the sill. Satellite altimeter data near the FBC show cyclonic anomalies propagating along the northern slope of the channel, resembling the surface eddies associated with the overflow variability in the model. A cross-channel circulation over the FBC sill, driven by frictional bottom boundary layers, resulted in convergence/divergence zones near the southern/northern slopes and pinching/spreading of isotherms across the channel, similar to the observation-based mechanism proposed by Johnson and Sanford (1992). |
format |
Article in Journal/Newspaper |
author |
Ezer, Tal |
author_facet |
Ezer, Tal |
author_sort |
Ezer, Tal |
title |
Topographic Influence on Overflow Dynamics: Idealized Numerical Simulations and the Faroe Bank Channel Overflow |
title_short |
Topographic Influence on Overflow Dynamics: Idealized Numerical Simulations and the Faroe Bank Channel Overflow |
title_full |
Topographic Influence on Overflow Dynamics: Idealized Numerical Simulations and the Faroe Bank Channel Overflow |
title_fullStr |
Topographic Influence on Overflow Dynamics: Idealized Numerical Simulations and the Faroe Bank Channel Overflow |
title_full_unstemmed |
Topographic Influence on Overflow Dynamics: Idealized Numerical Simulations and the Faroe Bank Channel Overflow |
title_sort |
topographic influence on overflow dynamics: idealized numerical simulations and the faroe bank channel overflow |
publisher |
ODU Digital Commons |
publishDate |
2006 |
url |
https://digitalcommons.odu.edu/ccpo_pubs/127 https://digitalcommons.odu.edu/cgi/viewcontent.cgi?article=1136&context=ccpo_pubs |
long_lat |
ENVELOPE(-8.667,-8.667,60.917,60.917) |
geographic |
Faroe Bank |
geographic_facet |
Faroe Bank |
genre |
Denmark Strait NADW North Atlantic Deep Water North Atlantic |
genre_facet |
Denmark Strait NADW North Atlantic Deep Water North Atlantic |
op_source |
CCPO Publications |
op_relation |
https://digitalcommons.odu.edu/ccpo_pubs/127 https://digitalcommons.odu.edu/cgi/viewcontent.cgi?article=1136&context=ccpo_pubs |
_version_ |
1766396639201722368 |