Observing mesoscale eddy effects on mode-water subduction and transport in the North Pacific

Xu, Lixiao; Li, Peiliang; Xie, Shang‐Ping; Liu, Qinyu; Liu, Cong; Gao, Wendian

doi:10.1038/ncomms10505

Cited by 95 publications

(97 citation statements)

References 47 publications

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“…According to Qu and Chen [42] and Wang et al [43], the STMW located between the isopycnal surfaces of 25.0 σ θ and 25.6 σ θ. Its volume varies significantly between 25 and 50 S v [44,45]. Thus, the observed SAE can transport 1 ~2% of the total STMW.…”

Section: Discussionmentioning

confidence: 98%

Observations of an Extra-Large Subsurface Anticyclonic Eddy in the Northwestern Pacific Subtropical Gyre

Nan¹,

Yu²,

Wei³

et al. 2017

J Marine Sci Res Dev

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An extra-large subsurface anticyclonic eddy (SAE) with horizontal scale of 470 km was detected in the northwestern Pacific subtropical gyre by in situ measurements in October 2014. The SAE exhibited a lens-shaped vertical structure with shoaling of the seasonal thermocline and deepening of the main thermocline. Consequently, the water in the eddy core was colder above 200 m and warmer below 200 m than the surrounding waters with maximum temperature anomalies of -1.2°C and 3.5°C located at ~100 m and ~450 m depths, respectively. The central water mass of the SAE was characterized as low potential vorticity water, i.e., the north Pacific Subtropical Mode Water (STMW). Swirl velocity of the SAE was directly observed by ship-mounted ADCP (Acoustic Doppler Current Profilers). The maximum azimuthal velocity reached 0.35 ms -1 near a 110 km radius at ~ 200 m depth, which was comparable with the maximum velocity of the northward Kuroshio east of Taiwan at the same depth. Threedimensional structure and evolutionary process of the SAE were also presented using Argo float profile data as well as the satellite altimeter data. The results indicated that the SAE was generated in the region of the STMW in February, then propagated westward over 1500 km at a mean speed of ~0.06 ms -1 and finally disappeared east of Taiwan in December, transporting ~0.5 Sv (Sv=10 6 m 3 s -1 ) STMW..

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Section: Discussionmentioning

confidence: 98%

Observations of an Extra-Large Subsurface Anticyclonic Eddy in the Northwestern Pacific Subtropical Gyre

Nan¹,

Yu²,

Wei³

et al. 2017

J Marine Sci Res Dev

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show abstract

“…The method is not suitable to follow deep vortexes that do not show a clear signature at surface, both on current and SSH fields. These vortexes can indeed occur in mode-water conditions, where a concurrent depression and elevation of isopycnal surfaces develops along the thermocline (Xu et al 2016;Gaube et al 2014). A further possible improvement concerns a more refined definition of rotational velocity, even though we think that it will not have a significant impact.…”

Section: Dmentioning

confidence: 96%

Benchmarking the mesoscale variability in global ocean eddy-permitting numerical systems

et al. 2017

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The role of data assimilation procedures on representing ocean mesoscale variability is assessed by applying eddy statistics to a state-of-the-art global ocean reanalysis (C-GLORS), a free global ocean simulation (performed with the NEMO system) and an observation-based dataset (ARMOR3D) used as an independent benchmark. Numerical results are computed on a 1/4 • horizontal grid (ORCA025) and share the same resolution with ARMOR3D dataset. This "eddy-permitting" resolution is sufficient to allow ocean eddies to form. Further to assessing the eddy statistics from three different datasets, a global threedimensional eddy detection system is implemented in order to bypass the need of regional-dependent definition of thresholds, typical of commonly adopted eddy detection algorithms. It thus provides full three-dimensional eddy Istituto Nazionale di Geofisica e Vulcanologia (INGV), Bologna, Italy statistics segmenting vertical profiles from local rotational velocities. This criterion is crucial for discerning real eddies from transient surface noise that inevitably affects any twodimensional algorithm. Data assimilation enhances and corrects mesoscale variability on a wide range of features that cannot be well reproduced otherwise. The free simulation fairly reproduces eddies emerging from western boundary currents and deep baroclinic instabilities, while underestimates shallower vortexes that populate the full basin. The ocean reanalysis recovers most of the missing turbulence, shown by satellite products , that is not generated by the model itself and consistently projects surface variability deep into the water column. The comparison with the statistically reconstructed vertical profiles from ARMOR3D show that ocean data assimilation is able to embed variability into the model dynamics, constraining eddies with in situ and altimetry observation and generating them consistently with local environment.

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“…Furthermore, SST and surface geostrophic currents (Equations (1)- (3)) were also adopted to further validate the tracking accuracy. Xu et al [45] deployed 17 Argo floats to track an anticyclonic eddy from 27 March 2014 to 10 September 2014 in the North Pacific Ocean. Three tracking methods were applied to track this anticyclonic eddy.…”

Section: Validationmentioning

confidence: 99%

An Improved Automatic Algorithm for Global Eddy Tracking Using Satellite Altimeter Data

et al. 2017

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Abstract:In this paper, we propose a new hybrid mesoscale eddy tracking method to enhance the eddy tracking accuracy from global satellite altimeter data. This method integrates both physical and geometric eddy properties (including the distance between eddies, the area and amplitude of eddy, and the shape of the eddy edge) via the output of detection and the calculation of Hausdorff distance, which could describe the similarity between eddy boundaries. We applied the proposed hybrid method to several previously reported eddies and compared the results with those from two traditional tracking methods. A quantitative comparison indicates that the hybrid algorithm can better reveal eddy signals in terms of their spatial scale, amplitude, lifespan, and splitting. The hybrid method was used for global mesoscale eddies tracking from 1993 to 2015. Global distributions of net eddy numbers revealed that the sources of eddies are located along the eastern boundaries of the world oceans, while the sinks of eddies are located along the western boundaries. The lifespan distribution of eddies exhibited steep growth from high and low latitudes to middle latitudes. A clear divergent pathway demonstrates that cyclonic/anticyclonic eddies tend to travel poleward/equatorward in the world oceans.

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Observing mesoscale eddy effects on mode-water subduction and transport in the North Pacific

Cited by 95 publications

References 47 publications

Observations of an Extra-Large Subsurface Anticyclonic Eddy in the Northwestern Pacific Subtropical Gyre

Observations of an Extra-Large Subsurface Anticyclonic Eddy in the Northwestern Pacific Subtropical Gyre

Benchmarking the mesoscale variability in global ocean eddy-permitting numerical systems

An Improved Automatic Algorithm for Global Eddy Tracking Using Satellite Altimeter Data

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