Altimetry and surface currents

To help fishermen, CATSAT provides maps of sea level anomaly from altimetry. Altimetric maps are specially reliable as they are unaffected by the presence of clouds.

• red-orange zones correspond to positive anomalies or "highs" of the surface topography.
• blue zones correspond to negative anomalies or "lows" of the surface topography.
• the highs and lows can reach several tens of centimeters.

Away from the equator, these anomalies generate currents that rotate around highs and lows at the ocean surface, just like winds rotate around high and low pressure areas, in the atmosphere.
In the Northern Hemisphere, currents flow along the contour lines of the topography, leaving higher SLA values to their right and lower values to their left. In the Southern Hemisphere, currents flow in the opposite direction. Current velocity is proportional to the slope of the topography.