Surface currents, a pinch of winds with altimetry

Image of the Month - April 2013

Map averaged for the 2000-2008 period of high resolution currents computed from altimetry and scatterometer data (Credits Legos/CNRS).

Ocean surface topography is not the whole story of currents. Winds play a definite role in surface currents. So, to know more accurately ocean surface circulation, one have to mix altimetry-derived currents (geostrophic) with wind-derived components also called "Ekman currents" from the theory described by Dr V. W. Ekman, a Swedish oceanographer.

However, satellites can also be used, even though not altimetric ones. Scatterometers enable to measure winds speeds and directions at the surface of the oceans. Mixing geostrophic currents and scatterometers-derived ones, one can obtain more realistics and useful currents to explain, e.g. surface drifters trajectories, but also biology including cholorophyll concentration in the ocean.

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References:

  • Sudre Joël, Christophe Maes and Véronique Garçon, 2013. On the global estimates of geostrophic and Ekman surface currents, Limnology and Oceanography: Fluids and Environments (L&O:F&E), Volume 3 (2013): 1–20, DOI: 10.1215/21573689-2071927