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Journal of Geophysical Research: Oceans

Can meddies be detected by satellite altimetry?


  • Detlef Stammer,

  • Hans-Harald Hinrichsen,

  • Rolf H. Käse


Geosat Exact Repeat Mission altimeter data have been used to estimate the sea surface height anomaly relative to a 2-year mean reference surface in the eastern North Atlantic Ocean. Horizontal maps of the sea surface height anomaly for various periods were constructed by means of an objective analysis procedure. The mean sea level was approximated by the dynamic topography from climatological hydrographic data. Results were compared to the dynamic topography calculated from hydrographic ground truth data sampled during March 1988 on an eddy-resolving station network in the Iberian Basin. Despite the low signal-to-noise ratio of the altimeter data in this part of the ocean, the agreement of the altimeter signal with hydrographic measurements is found to be significant. Individual cyclonic and anticyclonic eddies in the Mediterranean outflow are identified in the altimetric maps. The information visible in the sea surface height is significantly correlated with the dynamic topography of the layer 500/3000 dbar containing the core of the Mediterranean outflow and maximum velocities of the baroclinic eddies. The successive development of the identified eddies as studied from a sequence of sea surface height maps indicates a slight westward drift of the most pronounced feature with approximately 1.9 cm/s propagation velocity. The inferred path of that feature is consistent with additional information from moored current meter data.

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