Identification of Marine Eddies from Altimetric Maps

Isern‐Fontanet, Jordi; Garcı́a-Ladona, Emilio; Font, Jordi

doi:10.1175/1520-0426(2003)20<772:iomefa>2.0.co;2

Cited by 285 publications

(229 citation statements)

References 31 publications

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“…Eddy detection and tracking algorithms based on altimetry data have been widely used to investigate mesoscale structures in both space and time (Isern-Fontanet and E. Garcìa-Ladona, 2003;Chelton et al, 2007Chelton et al, , 2011Escudier et al, 2016;Yi et al, 2014;Schütte et al, 2016;Mason and Pascual, 2013). These algorithms, applied on global and regional scales, have been successful in the characterization of several properties, such as polarity, propagation pathway, lifetime, radius and amplitude.…”

Section: Methodsmentioning

confidence: 99%

“…The former are based on the calculation of some dynamic fields and define eddies based on the 10 closed contours of a threshold value. The physical fields computed are SLA, Sea Surface Height (SSH) Chaigneau et al, 2009), vorticity (McWilliams, 1999 and velocity gradient tensor or Okubo-Weiss parameter (W) (Penven and Echevin, 2005;Chelton et al, 2007;Isern-Fontanet and E. Garcìa-Ladona, 2003 are based on the curvature or shape of the instantaneous flow field. Several studies make use of both physical and geometrical methods to better explain the structure of mesoscale eddies.…”

Section: Methodsmentioning

confidence: 99%

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Mesoscale Eddies in the Algerian Basin: do they differ as a function of their formation site?

Pessini¹,

Olita²,

Cotroneo³

et al. 2018

Preprint

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Abstract. The circulation of the Western Mediterranean Sea (WMED) is dominated by highly variable and heterogeneous mesoscale circulation, strongly driven by the formation and propagation of eddies (cyclonic and anticyclonic) mainly acting in the Algerian Basin. Anticyclones are characterized by longer life, so potentially contributing to a large extent to the mesoscale characterization of the basin. Hereafter we will take into account only anticyclonic structures.In order to investigate the spatial and temporal distribution of eddy generation and their respective paths in the Algerian Basin, We find that anticyclonic short-life eddies mostly occur in the northern portion of the domain, north of 39•

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Mesoscale Eddies in the Algerian Basin: do they differ as a function of their formation site?

Pessini¹,

Olita²,

Cotroneo³

et al. 2018

Preprint

View full text Add to dashboard Cite

show abstract

“…To reduce the measurement noise, a 7-point stencil width was used for computation of the dynamic parameters, as recommended in Arbic et al (2012). At the surface, meddy signatures were often mixed with other dynamical structures; therefore we identified meddy surface signals from local extrema of the sea-level (Isern-Fontanet et al, 2003). These extrema are given by the Laplacian of sea-level height: ω 0 = g f ζ .…”

Section: Methodsmentioning

confidence: 99%

Surface signature of Mediterranean water eddies in the Northeastern Atlantic: effect of the upper ocean stratification

Bashmachnikov

Carton

2012

Ocean Sci.

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Abstract. Meddies, intra-thermocline eddies of Mediterranean water, can often be detected at the sea surface as positive sea-level anomalies. Here we study the surface signature of several meddies tracked with RAFOS floats and AVISO altimetry.While pushing its way through the water column, a meddy raises isopycnals above. As a consequence of potential vorticity conservation, negative relative vorticity is generated in the upper layer. During the initial period of meddy acceleration after meddy formation or after a stagnation stage, a cyclonic signal is also generated at the sea-surface, but mostly the anticyclonic surface signal follows the meddy.Based on geostrophy and potential vorticity balance, we present theoretical estimates of the intensity of the surface signature. It appears to be proportional to the meddy core radius and to the Coriolis parameter, and inversely proportional to the core depth and buoyancy frequency. This indicates that surface signature of a meddy may be strongly reduced by the upper ocean stratification. Using climatic distribution of the stratification intensity, we claim that the southernmost limit for detection in altimetry of small meddies (with radii on the order of 10-15 km) should lie in the subtropics (35-45 • N), while large meddies (with radii of 25-30 km) could be detected as far south as the northern tropics (25-35 • N). Those results agree with observations.

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“…While the results are not strongly sensitive to the details, the tracking can be improved somewhat regionally by fine tuning the tracking parameters [Isern-Fontanet et al, 2003Morrow et al, 2004]. For example, smaller values of W result in more tracked eddies in regions of small SSH variance but reduce the number of tracked eddies in regions of large SSH variance.…”

Section: Appendix A: Automated Eddy-tracking Proceduresmentioning

confidence: 99%

Global observations of large oceanic eddies

Chelton

Schlax

Samelson

et al. 2007

Geophysical Research Letters

1,011

939

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[1] Ten years of sea-surface height (SSH) fields constructed from the merged TOPEX/Poseidon (T/P) and ERS-1/2 altimeter datasets are analyzed to investigate mesoscale variability in the global ocean. The higher resolution of the merged dataset reveals that more than 50% of the variability over much of the World Ocean is accounted for by eddies with amplitudes of 5 -25 cm and diameters of 100-200 km. These eddies propagate nearly due west at approximately the phase speed of nondispersive baroclinic Rossby waves with preferences for slight poleward and equatorward deflection of cyclonic and anticyclonic eddies, respectively. The vast majority of the eddies are found to be nonlinear.

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Identification of Marine Eddies from Altimetric Maps

Cited by 285 publications

References 31 publications

Mesoscale Eddies in the Algerian Basin: do they differ as a function of their formation site?

Mesoscale Eddies in the Algerian Basin: do they differ as a function of their formation site?

Surface signature of Mediterranean water eddies in the Northeastern Atlantic: effect of the upper ocean stratification

Global observations of large oceanic eddies

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