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Thomas Valran - One of the best experts on this subject based on the ideXlab platform.
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influence of Coriolis force upon bottom boundary layers in a large scale gravity current experiment implications for evolution of sinuous deep water channel systems
Journal of Geophysical Research, 2020Co-Authors: Davarpanah S Jazi, Mathew G Wells, Jeff Peakall, R M Dorrell, Robert E Thomas, Gareth M Keevil, Stephen E Darby, Joel Sommeria, Samuel Viboud, Thomas ValranAbstract:Oceanic density currents in many deep‐water channels are strongly influenced by the Coriolis force. The dynamics of the bottom‐boundary layer in large geostrophic flows, and low Rossby number turbidity currents, are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large‐scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements, or in previous small‐scale rotating laboratory experiments. We present results from a large, 13 m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near‐bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ror=U/Rf, where U is the depth‐averaged velocity,the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer‐bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left‐ and right‐ turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Many of the largest currents in the oceans depths are dense, gravity‐driven, flows that pour down deep‐water channels. These large gravity currents include dense overflows, as well as sediment‐laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left‐turning versus a right‐turning bend. Our observations are relevant to the large deep‐water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous, however recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near‐bed patterns of erosion and deposition.
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Influence of Coriolis force upon bottom boundary layers in a large‐scale gravity current experiment: Implications for evolution of sinuous deep‐water channel systems
Journal of Geophysical Research. Oceans, 2020Co-Authors: Shahrzad Davarpanah Jazi, Mathew G Wells, Jeff Peakall, R M Dorrell, Robert E Thomas, Gareth M Keevil, Stephen E Darby, Joel Sommeria, Samuel Viboud, Thomas ValranAbstract:Oceanic density currents in many deep‐water channels are strongly influenced by the Coriolis force. The dynamics of the bottom‐boundary layer in large geostrophic flows, and low Rossby number turbidity currents, are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large‐scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements, or in previous small‐scale rotating laboratory experiments. We present results from a large, 13 m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near‐bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ror=U/Rf, where U is the depth‐averaged velocity,the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer‐bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left‐ and right‐ turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Many of the largest currents in the oceans depths are dense, gravity‐driven, flows that pour down deep‐water channels. These large gravity currents include dense overflows, as well as sediment‐laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left‐turning versus a right‐turning bend. Our observations are relevant to the large deep‐water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous, however recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near‐bed patterns of erosion and deposition.
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Influence of Coriolis Force Upon Bottom Boundary Layers in a Large‐Scale Gravity Current Experiment: Implications for Evolution of Sinuous Deep‐Water Channel Systems
Journal of Geophysical Research. Oceans, 2020Co-Authors: Shahrzad Davarpanah Jazi, Jeff Peakall, Joel Sommeria, Samuel Viboud, M Wells, R Dorrell, R Thomas, G Keevil, S Darby, Thomas ValranAbstract:Oceanic density currents in many deep-water channels are strongly influenced by the Coriolis force. The dynamics of the bottom boundary layer in large geostrophic flows and low Rossby number turbidity currents are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large-scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements or in previous small-scale rotating laboratory experiments. We present results from a large, 13-m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near-bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ro R = /Rf, where is the depth and time-averaged velocity, R is the radius of channel curvature, and f is the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left-and right-turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Plain Language Summary Many of the largest currents in the oceans depths are dense, gravity-driven, flows that pour down deep-water channels. These large gravity currents include dense overflows, as well as sediment-laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left-turning versus a right-turning bend. Our observations are relevant to the large deep-water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous; however, recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near-bed patterns of erosion and deposition.
Mathew G Wells - One of the best experts on this subject based on the ideXlab platform.
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influence of Coriolis force upon bottom boundary layers in a large scale gravity current experiment implications for evolution of sinuous deep water channel systems
Journal of Geophysical Research, 2020Co-Authors: Davarpanah S Jazi, Mathew G Wells, Jeff Peakall, R M Dorrell, Robert E Thomas, Gareth M Keevil, Stephen E Darby, Joel Sommeria, Samuel Viboud, Thomas ValranAbstract:Oceanic density currents in many deep‐water channels are strongly influenced by the Coriolis force. The dynamics of the bottom‐boundary layer in large geostrophic flows, and low Rossby number turbidity currents, are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large‐scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements, or in previous small‐scale rotating laboratory experiments. We present results from a large, 13 m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near‐bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ror=U/Rf, where U is the depth‐averaged velocity,the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer‐bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left‐ and right‐ turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Many of the largest currents in the oceans depths are dense, gravity‐driven, flows that pour down deep‐water channels. These large gravity currents include dense overflows, as well as sediment‐laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left‐turning versus a right‐turning bend. Our observations are relevant to the large deep‐water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous, however recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near‐bed patterns of erosion and deposition.
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Influence of Coriolis force upon bottom boundary layers in a large‐scale gravity current experiment: Implications for evolution of sinuous deep‐water channel systems
Journal of Geophysical Research. Oceans, 2020Co-Authors: Shahrzad Davarpanah Jazi, Mathew G Wells, Jeff Peakall, R M Dorrell, Robert E Thomas, Gareth M Keevil, Stephen E Darby, Joel Sommeria, Samuel Viboud, Thomas ValranAbstract:Oceanic density currents in many deep‐water channels are strongly influenced by the Coriolis force. The dynamics of the bottom‐boundary layer in large geostrophic flows, and low Rossby number turbidity currents, are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large‐scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements, or in previous small‐scale rotating laboratory experiments. We present results from a large, 13 m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near‐bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ror=U/Rf, where U is the depth‐averaged velocity,the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer‐bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left‐ and right‐ turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Many of the largest currents in the oceans depths are dense, gravity‐driven, flows that pour down deep‐water channels. These large gravity currents include dense overflows, as well as sediment‐laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left‐turning versus a right‐turning bend. Our observations are relevant to the large deep‐water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous, however recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near‐bed patterns of erosion and deposition.
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Coriolis forces influence the secondary circulation of gravity currents flowing in large scale sinuous submarine channel systems
Geophysical Research Letters, 2010Co-Authors: Remo Cossu, Mathew G WellsAbstract:A combination of centrifugal and Coriolis forces drive the secondary circulation of turbidity currents in sinuous channels, and hence determine where erosion and deposition of sediment occur. Using laboratory experiments we show that when centrifugal forces dominate, the density interface shows a superelevation at the outside of a channel bend. However when Coriolis forces dominate, the interface is always deflected to the right (in the Northern Hemisphere) for both left and right turning bends. The relative importance of either centrifugal or Coriolis forces can be described in terms of a Rossby number defined as Ro = U/fR, where U is the mean downstream velocity, f the Coriolis parameter and R the radius of curvature of the channel bend. Channels with larger bends at high latitudes have ∣Ro∣ < 1 and are dominated by Coriolis forces, whereas smaller, tighter bends at low latitudes have ∣Ro∣ ≫ 1 and are dominated by centrifugal forces.
Jeff Peakall - One of the best experts on this subject based on the ideXlab platform.
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influence of Coriolis force upon bottom boundary layers in a large scale gravity current experiment implications for evolution of sinuous deep water channel systems
Journal of Geophysical Research, 2020Co-Authors: Davarpanah S Jazi, Mathew G Wells, Jeff Peakall, R M Dorrell, Robert E Thomas, Gareth M Keevil, Stephen E Darby, Joel Sommeria, Samuel Viboud, Thomas ValranAbstract:Oceanic density currents in many deep‐water channels are strongly influenced by the Coriolis force. The dynamics of the bottom‐boundary layer in large geostrophic flows, and low Rossby number turbidity currents, are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large‐scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements, or in previous small‐scale rotating laboratory experiments. We present results from a large, 13 m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near‐bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ror=U/Rf, where U is the depth‐averaged velocity,the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer‐bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left‐ and right‐ turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Many of the largest currents in the oceans depths are dense, gravity‐driven, flows that pour down deep‐water channels. These large gravity currents include dense overflows, as well as sediment‐laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left‐turning versus a right‐turning bend. Our observations are relevant to the large deep‐water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous, however recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near‐bed patterns of erosion and deposition.
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Influence of Coriolis force upon bottom boundary layers in a large‐scale gravity current experiment: Implications for evolution of sinuous deep‐water channel systems
Journal of Geophysical Research. Oceans, 2020Co-Authors: Shahrzad Davarpanah Jazi, Mathew G Wells, Jeff Peakall, R M Dorrell, Robert E Thomas, Gareth M Keevil, Stephen E Darby, Joel Sommeria, Samuel Viboud, Thomas ValranAbstract:Oceanic density currents in many deep‐water channels are strongly influenced by the Coriolis force. The dynamics of the bottom‐boundary layer in large geostrophic flows, and low Rossby number turbidity currents, are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large‐scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements, or in previous small‐scale rotating laboratory experiments. We present results from a large, 13 m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near‐bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ror=U/Rf, where U is the depth‐averaged velocity,the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer‐bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left‐ and right‐ turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Many of the largest currents in the oceans depths are dense, gravity‐driven, flows that pour down deep‐water channels. These large gravity currents include dense overflows, as well as sediment‐laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left‐turning versus a right‐turning bend. Our observations are relevant to the large deep‐water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous, however recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near‐bed patterns of erosion and deposition.
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Influence of Coriolis Force Upon Bottom Boundary Layers in a Large‐Scale Gravity Current Experiment: Implications for Evolution of Sinuous Deep‐Water Channel Systems
Journal of Geophysical Research. Oceans, 2020Co-Authors: Shahrzad Davarpanah Jazi, Jeff Peakall, Joel Sommeria, Samuel Viboud, M Wells, R Dorrell, R Thomas, G Keevil, S Darby, Thomas ValranAbstract:Oceanic density currents in many deep-water channels are strongly influenced by the Coriolis force. The dynamics of the bottom boundary layer in large geostrophic flows and low Rossby number turbidity currents are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large-scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements or in previous small-scale rotating laboratory experiments. We present results from a large, 13-m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near-bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ro R = /Rf, where is the depth and time-averaged velocity, R is the radius of channel curvature, and f is the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left-and right-turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Plain Language Summary Many of the largest currents in the oceans depths are dense, gravity-driven, flows that pour down deep-water channels. These large gravity currents include dense overflows, as well as sediment-laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left-turning versus a right-turning bend. Our observations are relevant to the large deep-water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous; however, recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near-bed patterns of erosion and deposition.
Joel Sommeria - One of the best experts on this subject based on the ideXlab platform.
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influence of Coriolis force upon bottom boundary layers in a large scale gravity current experiment implications for evolution of sinuous deep water channel systems
Journal of Geophysical Research, 2020Co-Authors: Davarpanah S Jazi, Mathew G Wells, Jeff Peakall, R M Dorrell, Robert E Thomas, Gareth M Keevil, Stephen E Darby, Joel Sommeria, Samuel Viboud, Thomas ValranAbstract:Oceanic density currents in many deep‐water channels are strongly influenced by the Coriolis force. The dynamics of the bottom‐boundary layer in large geostrophic flows, and low Rossby number turbidity currents, are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large‐scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements, or in previous small‐scale rotating laboratory experiments. We present results from a large, 13 m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near‐bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ror=U/Rf, where U is the depth‐averaged velocity,the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer‐bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left‐ and right‐ turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Many of the largest currents in the oceans depths are dense, gravity‐driven, flows that pour down deep‐water channels. These large gravity currents include dense overflows, as well as sediment‐laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left‐turning versus a right‐turning bend. Our observations are relevant to the large deep‐water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous, however recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near‐bed patterns of erosion and deposition.
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Influence of Coriolis force upon bottom boundary layers in a large‐scale gravity current experiment: Implications for evolution of sinuous deep‐water channel systems
Journal of Geophysical Research. Oceans, 2020Co-Authors: Shahrzad Davarpanah Jazi, Mathew G Wells, Jeff Peakall, R M Dorrell, Robert E Thomas, Gareth M Keevil, Stephen E Darby, Joel Sommeria, Samuel Viboud, Thomas ValranAbstract:Oceanic density currents in many deep‐water channels are strongly influenced by the Coriolis force. The dynamics of the bottom‐boundary layer in large geostrophic flows, and low Rossby number turbidity currents, are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large‐scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements, or in previous small‐scale rotating laboratory experiments. We present results from a large, 13 m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near‐bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ror=U/Rf, where U is the depth‐averaged velocity,the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer‐bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left‐ and right‐ turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Many of the largest currents in the oceans depths are dense, gravity‐driven, flows that pour down deep‐water channels. These large gravity currents include dense overflows, as well as sediment‐laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left‐turning versus a right‐turning bend. Our observations are relevant to the large deep‐water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous, however recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near‐bed patterns of erosion and deposition.
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Influence of Coriolis Force Upon Bottom Boundary Layers in a Large‐Scale Gravity Current Experiment: Implications for Evolution of Sinuous Deep‐Water Channel Systems
Journal of Geophysical Research. Oceans, 2020Co-Authors: Shahrzad Davarpanah Jazi, Jeff Peakall, Joel Sommeria, Samuel Viboud, M Wells, R Dorrell, R Thomas, G Keevil, S Darby, Thomas ValranAbstract:Oceanic density currents in many deep-water channels are strongly influenced by the Coriolis force. The dynamics of the bottom boundary layer in large geostrophic flows and low Rossby number turbidity currents are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large-scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements or in previous small-scale rotating laboratory experiments. We present results from a large, 13-m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near-bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ro R = /Rf, where is the depth and time-averaged velocity, R is the radius of channel curvature, and f is the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left-and right-turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Plain Language Summary Many of the largest currents in the oceans depths are dense, gravity-driven, flows that pour down deep-water channels. These large gravity currents include dense overflows, as well as sediment-laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left-turning versus a right-turning bend. Our observations are relevant to the large deep-water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous; however, recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near-bed patterns of erosion and deposition.
Samuel Viboud - One of the best experts on this subject based on the ideXlab platform.
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influence of Coriolis force upon bottom boundary layers in a large scale gravity current experiment implications for evolution of sinuous deep water channel systems
Journal of Geophysical Research, 2020Co-Authors: Davarpanah S Jazi, Mathew G Wells, Jeff Peakall, R M Dorrell, Robert E Thomas, Gareth M Keevil, Stephen E Darby, Joel Sommeria, Samuel Viboud, Thomas ValranAbstract:Oceanic density currents in many deep‐water channels are strongly influenced by the Coriolis force. The dynamics of the bottom‐boundary layer in large geostrophic flows, and low Rossby number turbidity currents, are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large‐scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements, or in previous small‐scale rotating laboratory experiments. We present results from a large, 13 m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near‐bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ror=U/Rf, where U is the depth‐averaged velocity,the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer‐bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left‐ and right‐ turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Many of the largest currents in the oceans depths are dense, gravity‐driven, flows that pour down deep‐water channels. These large gravity currents include dense overflows, as well as sediment‐laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left‐turning versus a right‐turning bend. Our observations are relevant to the large deep‐water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous, however recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near‐bed patterns of erosion and deposition.
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Influence of Coriolis force upon bottom boundary layers in a large‐scale gravity current experiment: Implications for evolution of sinuous deep‐water channel systems
Journal of Geophysical Research. Oceans, 2020Co-Authors: Shahrzad Davarpanah Jazi, Mathew G Wells, Jeff Peakall, R M Dorrell, Robert E Thomas, Gareth M Keevil, Stephen E Darby, Joel Sommeria, Samuel Viboud, Thomas ValranAbstract:Oceanic density currents in many deep‐water channels are strongly influenced by the Coriolis force. The dynamics of the bottom‐boundary layer in large geostrophic flows, and low Rossby number turbidity currents, are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large‐scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements, or in previous small‐scale rotating laboratory experiments. We present results from a large, 13 m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near‐bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ror=U/Rf, where U is the depth‐averaged velocity,the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer‐bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left‐ and right‐ turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Many of the largest currents in the oceans depths are dense, gravity‐driven, flows that pour down deep‐water channels. These large gravity currents include dense overflows, as well as sediment‐laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left‐turning versus a right‐turning bend. Our observations are relevant to the large deep‐water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous, however recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near‐bed patterns of erosion and deposition.
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Influence of Coriolis Force Upon Bottom Boundary Layers in a Large‐Scale Gravity Current Experiment: Implications for Evolution of Sinuous Deep‐Water Channel Systems
Journal of Geophysical Research. Oceans, 2020Co-Authors: Shahrzad Davarpanah Jazi, Jeff Peakall, Joel Sommeria, Samuel Viboud, M Wells, R Dorrell, R Thomas, G Keevil, S Darby, Thomas ValranAbstract:Oceanic density currents in many deep-water channels are strongly influenced by the Coriolis force. The dynamics of the bottom boundary layer in large geostrophic flows and low Rossby number turbidity currents are very important for determining the erosion and deposition of sediment in channelized contourite currents and many large-scale turbidity currents. However, these bottom boundary layers are notoriously difficult to resolve with oceanic field measurements or in previous small-scale rotating laboratory experiments. We present results from a large, 13-m diameter, rotating laboratory platform that is able to achieve both stratified and highly turbulent flows in regimes where the rotation is sufficiently rapid that the Coriolis force can potentially dominate. By resolving the dynamics of the turbulent bottom boundary in straight and sinuous channel sections, we find that the Coriolis force can overcome centrifugal force to switch the direction of near-bed flows in channel bends. This occurs for positive Rossby numbers less than +0.8, defined as Ro R = /Rf, where is the depth and time-averaged velocity, R is the radius of channel curvature, and f is the Coriolis parameter. Density and velocity fields decoupled in channel bends, with the densest fluid of the gravity current being deflected to the outer bend of the channel by the centrifugal force, while the location of velocity maximum shifted with the Coriolis force, leading to asymmetries between left-and right-turning bends. These observations of Coriolis effects on gravity currents are synthesized into a model of how sedimentary structures might evolve in sinuous turbidity current channels at various latitudes. Plain Language Summary Many of the largest currents in the oceans depths are dense, gravity-driven, flows that pour down deep-water channels. These large gravity currents include dense overflows, as well as sediment-laden turbidity currents and contourite flows. The dynamics of these gravity currents can be strongly affected by the Coriolis force. This study examines the effect of the Coriolis force on the flow structure of oceanic gravity currents flowing through straight and sinuous channels. A set of 22 experiments were carried out on the world's largest rotating experimental facility, the LEGI Coriolis platform in Grenoble, France. Our detailed measurements of velocity and internal density structure imply that at higher latitudes Coriolis force dominates and changes the direction of the flow near the bed leading to differences between flows going around a left-turning versus a right-turning bend. Our observations are relevant to the large deep-water channels formed on the ocean floor by successive turbidity currents. Near the Equator these channels tend to be noticeably sinuous; however, recent studies have shown that this sinuosity decreases with latitude. One possibility is that latitudinal variations in the Coriolis force may influence the evolution of these channels through changing near-bed patterns of erosion and deposition.