Subthermocline Eddies over the Washington Continental Slope as Observed by Seagliders, 2003–09

Pelland, Noel A.; Eriksen, Charles C.; Lee, Craig M.

doi:10.1175/jpo-d-12-086.1

Cited by 97 publications

(148 citation statements)

References 91 publications

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“…For example, Klymak et al (2015) reported coherent eddies of California Undercurrent Water in the eastern subpolar North Pacific, likely spun off of topographic features along the eastern boundary (Pelland et al 2013). Reported variability in observed submesoscale spectral slopes (Klymak et al 2015;Callies and Ferrari 2013) may be in part a signature of these features.…”

Section: (Vi) Nonstationarity or Inhomogeneitymentioning

confidence: 99%

Submesoscale Water-Mass Spectra in the Sargasso Sea

Kunze

Klymak

Lien

et al. 2015

Journal of Physical Oceanography

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Submesoscale stirring contributes to the cascade of tracer variance from large to small scales. Multiple nested surveys in the summer Sargasso Sea with tow-yo and autonomous platforms captured submesoscale water-mass variability in the seasonal pycnocline at 20-60-m depths. To filter out internal waves that dominate dynamic signals on these scales, spectra for salinity anomalies on isopycnals were formed. Salinitygradient spectra are approximately flat with slopes of 20.2 6 0.2 over horizontal wavelengths of 0.03-10 km. While the two to three realizations presented here might be biased, more representative measurements in the literature are consistent with a nearly flat submesoscale passive tracer gradient spectrum for horizontal wavelengths in excess of 1 km. A review of mechanisms that could be responsible for a flat passive tracer gradient spectrum rules out (i) quasigeostrophic eddy stirring, (ii) atmospheric forcing through a relict submesoscale winter mixed layer structure or nocturnal mixed layer deepening, (iii) a downscale vortical-mode cascade, and (iv) horizontal diffusion because of shear dispersion of diapycnal mixing. Internal-wave horizontal strain appears to be able to explain horizontal wavenumbers of 0.1-7 cycles per kilometer (cpkm) but not the highest resolved wavenumbers (7-30 cpkm). Submesoscale subduction cannot be ruled out at these depths, though previous observations observe a flat spectrum well below subduction depths, so this seems unlikely. Primitive equation numerical modeling suggests that nonquasigeostrophic subinertial horizontal stirring can produce a flat spectrum. The last need not be limited to mode-one interior or surface Rossby wavenumbers of quasigeostrophic theory but may have a broaderband spectrum extending to smaller horizontal scales associated with frontogenesis and frontal instabilities as well as internal waves.

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Section: (Vi) Nonstationarity or Inhomogeneitymentioning

confidence: 99%

Submesoscale Water-Mass Spectra in the Sargasso Sea

Kunze

Klymak

Lien

et al. 2015

Journal of Physical Oceanography

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“…By comparing its dead reckoning navigation and GPS fixes at the surface, they also deduce a current between two surfacings-hereafter referred to as the ''depth-average currents'' (DAC)-representing the mean currents averaged over each dive. A compass calibration has been carried out before each deployment allowing DAC to be used to reference geostrophic velocities as commonly done in previous studies [Gourdeau et al, 2008;Davis et al, 2008;Bouffard et al, 2010Bouffard et al, , 2012Pietri et al, 2013;Høydalsvik et al, 2013;Pelland et al, 2013;Pietri et al, 2014;Bosse et al, 2015;Thomsen et al, 2016].…”

Section: Gliders Datamentioning

confidence: 99%

“…By allowing a relatively high horizontal resolution (distance between consecutive profiles $2-4 km), gliders can dynamically characterize small-scale SCVs [Martin et al, 2009;Fan et al, 2013;Pelland et al, 2013;Bosse et al, 2015;Thomsen et al, 2016].…”

Section: Introductionmentioning

confidence: 99%

Scales and dynamics of Submesoscale Coherent Vortices formed by deep convection in the northwestern Mediterranean Sea

et al. 2016

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Since 2010, an intense effort in the collection of in situ observations has been carried out in the northwestern Mediterranean Sea thanks to gliders, profiling floats, regular cruises, and mooring lines. This integrated observing system enabled a year‐to‐year monitoring of the deep waters formation that occurred in the Gulf of Lions area during four consecutive winters (2010–2013). Vortical structures remnant of wintertime deep vertical mixing events were regularly sampled by the different observing platforms. These are Submesoscale Coherent Vortices (SCVs) characterized by a small radius (∼5–8 km), strong depth‐intensified orbital velocities (∼10–20 cm s−1) with often a weak surface signature, high Rossby (∼0.5) and Burger numbers O(0.5–1). Anticyclones transport convected waters resulting from intermediate (∼300 m) to deep (∼2000 m) vertical mixing. Cyclones are characterized by a 500–1000 m thick layer of weakly stratified deep waters (or bottom waters that cascaded from the shelf of the Gulf of Lions in 2012) extending down to the bottom of the ocean at ∼2500 m. The formation of cyclonic eddies seems to be favored by bottom‐reaching convection occurring during the study period or cascading events reaching the abyssal plain. We confirm the prominent role of anticyclonic SCVs and shed light on the important role of cyclonic SCVs in the spreading of a significant amount (∼30%) of the newly formed deep waters away from the winter mixing areas. Since they can survive until the following winter, they can potentially have a great impact on the mixed layer deepening through a local preconditioning effect.

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“…These subsurface anticyclonic eddies (SAEs) play an important role in the near-coastal salinity, oxygen, and nutrient distributions [14]. Pelland et al [15] detected 20 SAEs and 10 subsurface cyclonic eddies (SCEs) in the California Current System associated with the California Undercurrent.…”

Section: Introductionmentioning

confidence: 99%

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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Subthermocline Eddies over the Washington Continental Slope as Observed by Seagliders, 2003–09

Cited by 97 publications

References 91 publications

Submesoscale Water-Mass Spectra in the Sargasso Sea

Submesoscale Water-Mass Spectra in the Sargasso Sea

Scales and dynamics of Submesoscale Coherent Vortices formed by deep convection in the northwestern Mediterranean Sea

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

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