Structure and Kinematics of Synoptic Eddies in the Ocean: Theory and Modern Observations

G. K. Korotaev

Marine Hydrophysical Institute of RAS, Sevastopol, Russian Federation

e-mail: korotaevgren@mail.ru

Abstract

Purpose. Assessment of general ideas about the character of synoptic processes in the ocean which came out from the results of the experiment at the POLYMODE polygon, and quantitative verification of the previously developed model of intense eddies from the viewpoint of new data on the eddy characteristics in the open ocean obtained from the satellite altimetry observations constitute the aim of the article.

Methods and Results. Comparison of the characteristic features of synoptic variability in the ocean resulted from the observational data obtained at the POLYMODE polygon with the generalized analysis of modern satellite altimetry observations showed relevance of the previously formed notions implying that far from the jet currents, the eddies are relatively sparsely distributed over the ocean surface; at that they contain a significant portion of total energy on the synoptic scales. Quantitative verification of the previously constructed model of an intense synoptic eddy through its comparison with the eddy features revealed from the satellite altimetry observations showed, on the whole, satisfactory agreement between the theoretical characteristics and those observed. The altimetry-based median estimate of the eddy structure confirms existence of the eddy core including the main vorticity, and the trap zone in which the particles of the fluid surrounding the core are involved in the orbital motion. According to the observations, the cyclonic eddies drift mainly to the northwest, whereas the anticyclonic ones – to the southwest that is forecasted by the theoretical model. It is shown that the anomalous drift of the eddies along the meridian (the cyclonic eddies – to the south and the anticyclonic ones – to the north) is explained by the effect of mean currents. The distances, over which the eddies drift along the meridian, and the inclination angles of the eddy trajectories relative to the parallels are quantitatively close to those observed.

Conclusions. The results of processing the satellite altimetry observations confirm adequacy of the previously developed general notions about the character of the synoptic processes in the ocean and the physical prerequisites constituting a foundation for the theoretical model of an intense eddy radiating the Rossby waves. At that, interaction of the baroclinic and barotropic modes should be necessarily taken into account for more accurate reproduction of the eddy lifetime.

Keywords

synoptic eddies, Rossby waves, satellite altimetry, Polygon 70, POLYMODE program

Acknowledgements

The study was carried out in the Marine Hydrophysical Institute, RAS, at financial support of RSF (grant No. 17-77-30001).

Original russian text

Original Russian Text © G. K. Korotaev, 2020, published in MORSKOY GIDROFIZICHESKIY ZHURNAL, Vol. 36, Iss. 6, pp. 757-780 (2020)

For citation

Korotaev, G.K., 2020. Structure and Kinematics of Synoptic Eddies in the Ocean: Theory and Modern Observations. Physical Oceanography, 27(6), pp. 692-713. doi:10.22449/1573-160X-2020-6-692-713

DOI

10.22449/1573-160X-2020-6-692-713

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