Most of the kinetic energy of ocean circulation is contained in ubiquitous mesoscale eddies. Their prominent signatures in sea surface height have rendered satellite altimetry highly effective in observing global ocean eddies. Our knowledge of ocean eddy dynamics has grown by leaps and bounds since the advent of satellite altimetry in the early 1980s. A satellite’s fast sampling allows a broad view of the global distribution of eddy variability and its spatial structures. Since the early 1990s, the combination of data available from two simultaneous flying altimeters has resulted in a time-series record of global maps of ocean eddies. Despite the moderate resolution, these maps provide an opportunity to study the temporal and spatial variability of the surface signatures of eddies at a level of detail previously unavailable. A global census of eddies has been constructed to assess their population, polarity, intensity, and nonlinearity. The velocity and pattern of eddy propagation, as well as eddy transports of heat and salt, have been mapped globally. For the first time, the cascade of eddy energy through various scales has been computed from observations, providing evidence for the theory of ocean turbulence. Notwithstanding the tremendous progress made using existing observations, their limited resolution has prevented study of variability at wavelengths shorter than 100 km, where important eddy processes take place, ranging from energy dissipation to mixing and transport of water properties that are critical to understanding the ocean’s roles in Earth’s climate. The technology of radar interferometry promises to allow wide-swath measurement of sea surface height at a resolution that will resolve eddy structures down to 10 km. This approach holds the potential to meet the challenge of extending the observations to submesoscales and to set a standard for future altimetric measurement of the ocean.

Fu, L.-L., D.B. Chelton, P.-Y. Le Traon, and R. Morrow. 2010. Eddy dynamics from satellite altimetry. Oceanography 23(4):14–25, https://doi.org/10.5670/oceanog.2010.02.

Brachet, S., P.Y. Le Traon, and C. Le Provost. 2004. Mesoscale variability from a high-resolution model and from altimeter data in the North Atlantic Ocean. Journal of Geophysical Research 109, C12025. [CrossRef]
1. Capet, X., P. Klein, B.L. Hua, G. Lapeyre, and J.C. McWilliams. 2008. Surface kinetic energy transfer in surface quasi-geostrophic flows. Journal of Fluid Mechanics 604:165–174. [CrossRef]
2. Chaigneau, S., A. Gizolme, and C. Grados. 2008. Mesoscale eddies off Peru in altimeter records: Identification algorithms and eddy spatio-temporal patterns. Progress in Oceanography 79:106–119. [CrossRef]
3. Charney, J.G. 1971. Geostrophic turbulence. Journal of Atmospheric Science 28:1,087–1,095.
4. Chelton, D.B., M.G. Schlax, R.M. Samelson, and R.A. de Szoeke. 2007. Global observations of large oceanic eddies. Geophysical Research Letters 34, L15606. [CrossRef]
5. Chelton, D.B., M.G. Schlax, and R.M. Samelson. In press. Global observations of nonlinear mesoscale eddies. Progress in Oceanography.
6. Cheney, R.E., J.G. March, and B.D. Beckley. 1983. Global mesoscale variability from collinear tracks of Seasat altimeter data. Journal of Geophysical Research 88:4,343–4,354.
7. Cushman-Roisin, B., E.P. Chassignet, and B. Tang. 1990. Westward motion of mesoscale eddies. Journal of Physical Oceanography 20:758–768.
8. Ducet, N., P.Y. Le Traon, and G. Reverdin. 2000. Global high resolution mapping of ocean circulation from the combination of TOPEX/POSEIDON and ERS-1/2. Journal of Geophysical Research 105:19,477–19,498. [CrossRef]
9. Durand, M., L.-L. Fu, D.P. Lettenmaier, D.E. Alsdorf, E. Rodrigues, and D. Esteban-Fernandez. 2010. The Surface Water and Ocean Topography mission: Observing terrestrial surface water and oceanic submesoscale eddies. Proceedings of IEEE 98(5):766–779. [CrossRef]
10. Fu, L.-L. 1983. On the wavenumber spectrum of oceanic mesoscale variability observed by the Seasat altimeter. Journal of Geophysical Research 88:4,331–4,341.
11. Fu, L.-L. 2009. Pattern and velocity of propagation of the global ocean eddy variability. Journal of Geophysical Research 114, C11017. [CrossRef]
12. Fu, L.-L., and R. Ferrari. 2008. Observing oceanic submesoscale processes from space. Eos, Transactions American Geophysical Union 89(48):488. [CrossRef]
13. Fu, L.-L., and R. Rodriguez. 2004. High-resolution measurement of ocean surface topography by radar interferometry for oceanographic and geophysical applications. Pp. 209–224 in State of the Planet: Frontiers and Challenges. R.S.J. Sparks and C.J. Hawkesworth, eds, AGU Geophysical Monograph 150, IUGG Vol. 19.
14. Holloway, G. 1986. Estimation of oceanic eddy transports from satellite altimetry. Nature 323:243–244. [CrossRef]
15. Huang, N.E., C.D. Leitao, and C.G. Para. 1978. Large-scale Gulf Stream frontal study using GEOS3 radar altimeter data. Journal of Geophysical Research 83:4,673–4,682.
16. Isern-Fontanet, J., E. Garcia-Ladona, and J. Font. 2003. Identification of marine eddies from altimetric maps. Journal of Atmospheric and Oceanic Technology 20:772–778.
17. Jacobs, G.A., C.N. Barron, and R.C. Rhodes. 2001. Mesoscale characteristics. Journal of Geophysical Research 106:19,581–19,595. [CrossRef]
18. Klein, P., J. Isern-Fontanet, G. Lapeyre, G. Roullet, E. Danioux, B. Chapron, S. Le Gentil, and H. Sasaki. 2009. Diagnosis of vertical velocities in the upper ocean from high-resolution sea surface height. Geophysical Research Letters 36, L12603. [CrossRef]
19. Kuragano, T., and M. Kamachi. 2000. Global statistical space-time scales of oceanic variability estimated from the TOPEX/POSEIDON altimeter data. Journal of Geophysical Research 105(C1):955–974. [CrossRef]
20. Lapeyre, G., and P. Klein. 2006. Impact of the small-scale elongated filaments on the oceanic vertical pump. Journal of Marine Research 64:835–851. [CrossRef]
21. Le Traon, P.-Y., and R. Morrow. 2001. Ocean currents and eddies. Pp. 171–210 in Satellite Altimetry and Earth Sciences: A Handbook for Techniques and Applications. L.-L. Fu and A. Cazenave, eds, Academic Press, San Diego.
22. Le Traon, P.-Y. 1993. Comment on “Mesoscale variability in the Atlantic ocean from Geosat altimetry and WOCE high resolution numerical modeling by D. Stammer and C.W. Böning.” Journal of Physical Oceanography 23:2,729–2,732.
23. Le Traon, P.-Y., and G. Dibarboure. 2002. Velocity mapping capabilities of present and future altimeter missions: The role of high frequency signals. Journal of Atmospheric and Oceanic Technology 19:2,077–2,088.
24. Le Traon, P.-Y., F. Nadal, and N. Ducet. 1998. An improved mapping method of multi-satellite altimeter data. Journal of Atmospheric and Oceanic Technology 15:522–534.
25. Le Traon, P.-Y., P. Klein, B.L. Hua, and G. Dibarboure. 2008. Do altimeter data agree with interior or surface quasi-geostrophic theory? Journal of Physical Oceanography 38(5):1,137–1,142.
26. Marshall, J., E. Shuckburgh, H. Jones, and C. Hill. 2006. Estimates and implications of surface eddy diffusivity in the Southern Ocean derived from tracer transport. Journal of Physical Oceanography 36:1,806–1,821.
27. McWilliams, J.C., and G.R. Flierl. 1979. On the evolution of isolated, nonlinear vortices. Journal of Physical Oceanography 9:1,155–1,182.
28. Morrow, R.A., R. Coleman, J.A. Church, and D.B. Chelton. 1994. Surface eddy momentum flux and velocity variance in the Southern Ocean from GEOSAT altimetry. Journal of Physical Oceanography 24:2,050–2,071.
29. Morrow, R., F. Birol, D. Griffin, and J. Sudre. 2004. Divergent pathways of cyclonic and anti-cyclonic ocean eddies. Geophysical Research Letters 31, L24311. [CrossRef]
30. NRC (National Research Council). 2007. Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond. Committee on Earth Science and Applications from Space: A Community Assessment and Strategy for the Future, National Academies Press, Washington, DC, 456 pp.
31. Okubo, A. 1970. Horizontal dispersion of floatable particles in the vicinity of velocity singularities such as convergences. Deep-Sea Research 17:445–454.
32. Pascual, A., Y. Faugere, G. Larnicol, and P.-Y. Le Traon. 2006. Improved description of the ocean mesoscale variability by combining four satellite altimeters. Geophysical Research Letters 33, L02611. [CrossRef]
33. Qiu, B., and S. Chen. 2005. Eddy-induced heat transport in the subtropical North Pacific from Argo, TMI, and altimetry measurements. Journal of Physical Oceanography 35:458–473. [CrossRef]
34. Qiu, B., R.B. Scott, and S. Chen. 2008. Length scales of eddy generation and nonlinear evolution of the seasonally modulated South Pacific Subtropical Countercurrent. Journal of Physical Oceanography 38(7):1,515–1,528.
35. Rhines, P.B. 1977. The dynamics of unsteady currents. Pp. 189–318 in The Sea, vol. 6. E.D. Goldberg, I.N. McCave, J.J. O’Brien, and J.H. Steele, eds, John Wiley and Sons.
36. Robinson, A.R., ed. 1983. Eddies in Marine Science. Springer-Verlag, 609 pp.
37. Roemmich, D., and J. Gilson. 2001. Eddy transport of heat and thermocline waters in the North Pacific: A key to interannual/decadal climate variability? Journal of Physical Oceanography 31:675–687.
38. Sallée, J.B., K. Speer, R. Morrow, and R. Lumpkin. 2008. An estimate of Lagrangian eddy statistics and diffusion in the mixed layer of the Southern Ocean. Journal of Marine Research 66(4):441–463.
39. Samelson, R.M., and S. Wiggins. 2006. Lagrangian Transport in Geophysical Jets and Waves. Springer-Verlag, New York, 147 pp.
40. Schlax, M.G., and D.B. Chelton. 2003. The accuracies of crossover and parallel-track estimates of geostrophic velocities from TOPEX/POSEIDON and Jason altimeter data. Journal of Atmospheric and Oceanic Technology 20:1,196–1,211.
41. Scharffenberg, M.G., and D. Stammer. 2010. Seasonal variations of the large-scale geostrophic flow field and eddy kinetic energy inferred from the TOPEX/Poseidon and Jason-1 tandem mission data. Journal of Geophysical Research 115, C2. [CrossRef]
42. Scott, R.B., and F. Wang. 2005. Direct evidence of an oceanic inverse kinetic energy cascade from satellite altimetry Journal of Physical Oceanography 35(9):1,650–1,666.
43. Smith, K.S. 2007. The geography of linear baroclinic instability in Earth’s oceans. Journal of Marine Research 65:655–683. [CrossRef]
44. Stammer, D. 1997. Global characteristics of ocean variability estimated from regional TOPEX/POSEIDON altimeter measurements. Journal of Physical Oceanography 27:1,743–1,769.
45. Stammer, D. 1998. On eddy characteristics, eddy transports, and mean flow properties. Journal of Physical Oceanography 28:727–739.
46. Weiss, J. 1991. The dynamics of enstrophy transfer in two-dimensional hydrodynamics. Physica D 48:273–294. [CrossRef]
47. Wunsch, C. 1999. Where do ocean eddy heat fluxes matter? Journal of Geophysical Research 104:13,235–13,249. [CrossRef]
48. Zlotnicki, V., L.-L. Fu, and W. Patzert. 1989. Seasonal variability in a global sea level observed with GEOSAT altimetry. Journal of Geophysical Research 94:17,959–17,969. [CrossRef]

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.