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Observed deep energetic eddies by seamount wake.

Chen G, Wang D, Dong C, Zu T, Xue H, Shu Y, Chu X, Qi Y, Chen H - Sci Rep (2015)

Bottom Line: It remarkably deepens isotherm at deep layers by the amplitude of ~120 m and induces a maximal velocity amplitude about 0.18 m/s, which is far larger than the median velocity (0.02 m/s).The deep eddy is generated in a wake when a steering flow in the upper layer passes a seamount, induced by a surface cyclonic eddy.Deep eddies significantly increase the velocity intensity and enhance the mixing in the deep ocean, also have potential implication for deep-sea sediments transport.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.

ABSTRACT
Despite numerous surface eddies are observed in the ocean, deep eddies (a type of eddies which have no footprints at the sea surface) are much less reported in the literature due to the scarcity of their observation. In this letter, from recently collected current and temperature data by mooring arrays, a deep energetic and baroclinic eddy is detected in the northwestern South China Sea (SCS) with its intensity, size, polarity and structure being characterized. It remarkably deepens isotherm at deep layers by the amplitude of ~120 m and induces a maximal velocity amplitude about 0.18 m/s, which is far larger than the median velocity (0.02 m/s). The deep eddy is generated in a wake when a steering flow in the upper layer passes a seamount, induced by a surface cyclonic eddy. More observations suggest that the deep eddy should not be an episode in the area. Deep eddies significantly increase the velocity intensity and enhance the mixing in the deep ocean, also have potential implication for deep-sea sediments transport.

No MeSH data available.


Related in: MedlinePlus

Simulated currents at different depths.(a–e) Modeled current vectors at 50 m, 400 m, 600 m, 900 m and 1100 m. (f) Same as (e) but for the situation that the seamount shown in Fig. 1c is removed. Triangle and square represent the locations of the moorings A and B, respectively. The region in (b–f) is marked by red box in (a). Color shows the bathymetry, and white means the land. Maps are generated using MATLAB.
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f4: Simulated currents at different depths.(a–e) Modeled current vectors at 50 m, 400 m, 600 m, 900 m and 1100 m. (f) Same as (e) but for the situation that the seamount shown in Fig. 1c is removed. Triangle and square represent the locations of the moorings A and B, respectively. The region in (b–f) is marked by red box in (a). Color shows the bathymetry, and white means the land. Maps are generated using MATLAB.

Mentions: A South China Sea model (see Method for the analysis) is utilized to further the investigation of the effects of the seamount on the deep eddy qualitatively. The seamount reproduced by the model can be clearly identified although it is not exactly the same as that shown in Fig. 1b,c, because of the smoothed topography and model resolution. The model can reproduce the surface cyclonic eddy and the deep eddy as observed (Fig. 4). The cyclonic eddy at 400 m (the height of the seamount in the model) and the above can be seen clearly (Fig. 4a,b). At 600 m and deeper layer, the effect of seamount is evident: an anticyclonic eddy is generated to its north (Fig. 4c–e). When the seamount is removed by interpolating the surrounding depth to the seamount area, no anticyclonic deep eddy is found (Fig. 4f), which confirms the generation mechanism of the deep eddy as a steering flow passing a seamount.


Observed deep energetic eddies by seamount wake.

Chen G, Wang D, Dong C, Zu T, Xue H, Shu Y, Chu X, Qi Y, Chen H - Sci Rep (2015)

Simulated currents at different depths.(a–e) Modeled current vectors at 50 m, 400 m, 600 m, 900 m and 1100 m. (f) Same as (e) but for the situation that the seamount shown in Fig. 1c is removed. Triangle and square represent the locations of the moorings A and B, respectively. The region in (b–f) is marked by red box in (a). Color shows the bathymetry, and white means the land. Maps are generated using MATLAB.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663540&req=5

f4: Simulated currents at different depths.(a–e) Modeled current vectors at 50 m, 400 m, 600 m, 900 m and 1100 m. (f) Same as (e) but for the situation that the seamount shown in Fig. 1c is removed. Triangle and square represent the locations of the moorings A and B, respectively. The region in (b–f) is marked by red box in (a). Color shows the bathymetry, and white means the land. Maps are generated using MATLAB.
Mentions: A South China Sea model (see Method for the analysis) is utilized to further the investigation of the effects of the seamount on the deep eddy qualitatively. The seamount reproduced by the model can be clearly identified although it is not exactly the same as that shown in Fig. 1b,c, because of the smoothed topography and model resolution. The model can reproduce the surface cyclonic eddy and the deep eddy as observed (Fig. 4). The cyclonic eddy at 400 m (the height of the seamount in the model) and the above can be seen clearly (Fig. 4a,b). At 600 m and deeper layer, the effect of seamount is evident: an anticyclonic eddy is generated to its north (Fig. 4c–e). When the seamount is removed by interpolating the surrounding depth to the seamount area, no anticyclonic deep eddy is found (Fig. 4f), which confirms the generation mechanism of the deep eddy as a steering flow passing a seamount.

Bottom Line: It remarkably deepens isotherm at deep layers by the amplitude of ~120 m and induces a maximal velocity amplitude about 0.18 m/s, which is far larger than the median velocity (0.02 m/s).The deep eddy is generated in a wake when a steering flow in the upper layer passes a seamount, induced by a surface cyclonic eddy.Deep eddies significantly increase the velocity intensity and enhance the mixing in the deep ocean, also have potential implication for deep-sea sediments transport.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.

ABSTRACT
Despite numerous surface eddies are observed in the ocean, deep eddies (a type of eddies which have no footprints at the sea surface) are much less reported in the literature due to the scarcity of their observation. In this letter, from recently collected current and temperature data by mooring arrays, a deep energetic and baroclinic eddy is detected in the northwestern South China Sea (SCS) with its intensity, size, polarity and structure being characterized. It remarkably deepens isotherm at deep layers by the amplitude of ~120 m and induces a maximal velocity amplitude about 0.18 m/s, which is far larger than the median velocity (0.02 m/s). The deep eddy is generated in a wake when a steering flow in the upper layer passes a seamount, induced by a surface cyclonic eddy. More observations suggest that the deep eddy should not be an episode in the area. Deep eddies significantly increase the velocity intensity and enhance the mixing in the deep ocean, also have potential implication for deep-sea sediments transport.

No MeSH data available.


Related in: MedlinePlus