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- Dec. 1999: Measuring waves... with waves.
- Nov. 1999: Eddies: two sides to the story.
- Oct. 1999: Mediterranean tides are more than meets the eye.
- Sep. 1999: Mare nostrum, Mare incognita ?.
- Aug. 1999: Great Lakes as seen by Topex/Poseidon.
- Jul. 1999: Aral Sea could be rising from the dust.
- Jun. 1999: An eddy blown by the wind.
- May 1999: A turbulent sea.
- Apr. 1999: Jason-1 put to the test.
- Mar 1999: Observing the ocean to improve forecasting.
- Feb. 1999: Route du Rhum 1998.
- Jan. 1999: A glassy sea... of ridges and valleys.
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Eddies: two sides to the story
Image of the Month - November 1999
Algerian current eddy: sea surface temperature and altimetry, April 19, 1993. White lines show current velocity, derived from altimetry data, along the T/P satellite ground track; black lines show altimetric sea level measurements; colors indicate temperature (blue to red). (Credits Istituto di Fisica dell'Atmosfera CNR)
Satellite altimeters provide a very clear view of eddy structures, but other sensors are also capable of locating them. For example, sea surface temperature sensors "see" eddies as warm or cold spirals, whereas altimeters see the same structures as peaks and valleys. Depending on whether an eddy is a peak or valley, and depending on whether it is in the northern or southern hemisphere, we can determine its direction of rotation. Further, by looking at a peak's slope we can determine the velocity of the current inside the eddy, i.e., the steeper the slope the faster the current.
See also:
- Image of the month, January 2006 : Merging of altimetry data: proofs from other measurements
- Satellites Monitor The Mediterranean Pulse (pdf, 3.3 Mb).