Mean and Eddy Dynamics of the Main Thermocline

A downward blowing isothermal wall jet at moderate Reynolds numbers (1,500 to 8,500) with significant inflow turbulence (ca. 6%) was investigated. The flow configuration is an idealization of the air curtains of refrigerated display cases. Flow visualization using particle seeding was employed to identify the flow field eddy dynamics. Particle Image Velocimetry was used to examine the velocity fields in terms of mean and fluctuating values. These diagnostics showed that the air curtain entrainment was dominated by a large variety of eddies that engulfed ambient air into the air curtain. The velocity fields generally showed linear spreading, significant deceleration and high turbulence levels (ca. 25%). It was observed that the air curtain dynamics, velocity fields and growth were not significantly sensitive to Reynolds number variation between Re=3,800 and Re=8,500. However, at low air velocities (Re=1,500), the curtain was found to detach, leading to a large air curtain thickness and high curtain entrainment.

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Profile of an Isopycnal Surface in the Main Thermocline of the Sargasso Sea

Journal of Physical Oceanography ◽

10.1175/1520-0485(1973)003<0448:poaisi>2.0.co;2 ◽

1973 ◽

Vol 3 (4) ◽

pp. 448-457 ◽

Cited By ~ 26

Author(s):

Eli Joel Katz

Keyword(s):

Sargasso Sea ◽

Isopycnal Surface ◽

Main Thermocline

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Eddy Dynamics Near Sharp Interfaces and in Straining Flows

Progress in Industrial Mathematics at ECMI 2008 - Mathematics in Industry ◽

10.1007/978-3-642-12110-4_39 ◽

2010 ◽

pp. 267-272 ◽

Cited By ~ 2

Author(s):

J. C. R. Hunt ◽

I. Eames ◽

J. Westerweel

Keyword(s):

Eddy Dynamics ◽

Sharp Interfaces

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Advancing the simulation of mesoscale eddies: Backscatter schemes in eddy-permitting ocean simulations

10.5194/egusphere-egu21-12418 ◽

2021 ◽

Author(s):

Stephan Juricke ◽

Sergey Danilov ◽

Marcel Oliver ◽

Nikolay Koldunov ◽

Dmitry Sidorenko ◽

...

Keyword(s):

Kinetic Energy ◽

Large Scale ◽

Mesoscale Eddy ◽

Ocean Model ◽

Mean Flow ◽

Ocean Coupling ◽

Climate Simulations ◽

Flow Interactions ◽

To Come ◽

Eddy Dynamics

<p>Capturing mesoscale eddy dynamics is crucial for accurate simulations of the large-scale ocean currents as well as oceanic and climate variability. Eddy-mean flow interactions affect the position, strength and variations of mean currents and eddies are important drivers of oceanic heat transport and atmosphere-ocean-coupling. However, simulations at eddy-permitting resolutions are substantially underestimating eddy variability and eddy kinetic energy many times over. Such eddy-permitting simulations will be in use for years to come, both in coupled and uncoupled climate simulations. We present a set of kinetic energy backscatter schemes with different complexity as alternative momentum closures that can alleviate some eddy related biases such as biases in the mean currents, in sea surface height variability and in temperature and salinity. The complexity of the schemes reflects in their computational costs, the related simulation improvements and their adaptability to different resolutions. However, all schemes outperform classical viscous closures and are computationally less expensive than a related necessary resolution increase to achieve similar results. While the backscatter schemes are implemented in the ocean model FESOM2, the concepts can be adjusted to any ocean model including NEMO.</p>

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Anatomy of a Cyclonic Eddy in the Kuroshio Extension Based on High-Resolution Observations

Atmosphere ◽

10.3390/atmos10090553 ◽

2019 ◽

Vol 10 (9) ◽

pp. 553 ◽

Cited By ~ 2

Author(s):

Yongchui Zhang ◽

Xi Chen ◽

Changming Dong

Keyword(s):

High Resolution ◽

Mixed Layer ◽

Kuroshio Extension ◽

Mesoscale Eddies ◽

Cyclonic Eddy ◽

Intermediate Water ◽

Dipole Structure ◽

Significant Difference ◽

The Kuroshio ◽

Main Thermocline

Mesoscale eddies are common in the ocean and their surface characteristics have been well revealed based on altimetric observations. Comparatively, the knowledge of the three-dimensional (3D) structure of mesoscale eddies is scarce, especially in the open ocean. In the present study, high-resolution field observations of a cyclonic eddy in the Kuroshio Extension have been carried out and the anatomy of the observed eddy is conducted. The temperature anomaly exhibits a vertical monopole cone structure with a maximum of −7.3 °C located in the main thermocline. The salinity anomaly shows a vertical dipole structure with a fresh anomaly in the main thermocline and a saline anomaly in the North Pacific Intermediate Water (NPIW). The cyclonic flow displays an equivalent barotropic structure. The mixed layer is deep in the center of the eddy and thin in the periphery. The seasonal thermocline is intensified and the permanent thermocline is upward domed by 350 m. The subtropical mode water (STMW) straddled between the seasonal and permanent thermoclines weakens and dissipates in the eddy center. The salinity of NPIW distributed along the isopycnals shows no significant difference inside and outside the eddy. The geostrophic relation is approximately set up in the eddy. The nonlinearity—defined as the ratio between the rotational speed to the translational speed—is 12.5 and decreases with depth. The eddy-wind interaction is examined by high resolution satellite observations. The results show that the cold eddy induces wind stress aloft with positive divergence and negative curl. The wind induced upwelling process is responsible for the formation of the horizontal monopole pattern of salinity, while the horizontal transport results in the horizontal dipole structure of temperature in the mixed layer.

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