Getting smaller details

Image of the Month - September 2012

Comparisons between in situ results from a multi-sensor experiment north of Mallorca (14 May 2009) and data computed from altimetry using different processing,. The grey dots are the trajectories of drifting buoys launched at the same time (number “1” indicates the initial position, number “2” indicates the final position). The dynamic height computed from in situ (glider and CTD temperature and salinity fields) (a) is better matched by the absolute dynamic topography and derived geostrophic current from the high resolution plus bathymetry computation (d) on the same day than by the classical AVISO (b), or even the high resolution (c) computation. (Credits IMEDEA)

The merging of multiple altimeter missions improves the resolution of altimetry-derived maps. But the present configuration still lacks enough resolution for correctly sampling regional and coastal features. The Mediterranean Sea is an especially difficult area in this respect, since we are never far from shore. On the other hand, quite a lot of observations are available within this Sea.

To be able to detect smaller features, a second processing is done, to interpolate at smaller scale. The bathymetry is also taken into account, as it affects coastal circulation.

The future SWOT mission will completely change this kind of approach, by providing an image thanks to the swath measurements. In the meantime, and even afterwards to complete this mission, combining altimetry missions between them, and with other kind of data will enable better space/time resolutions.

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