Guide
What is an ocean eddy?
An ocean eddy is a large, slowly rotating body of water, often tens to hundreds of kilometres across, that can last for weeks or months.
Highs and lows
Altimeter satellites measure the height of the sea surface. A raised area (a high) is a warm-core eddy; a depressed area (a low) is a cold-core eddy. Gannet View draws sea level as contours and tags each strong high and low with its height.
Where they come from
Eddies form wherever a strong current meanders: the Gulf Stream off the US East Coast, the East Australian Current, the Agulhas off South Africa and others. They break away from the main current and then drift for weeks.
What the contours mean
Closer-together contour lines mean the sea surface slopes faster, which goes with faster flow around the eddy. The map draws the real satellite sea level for the day and states which day it is.
How current it is
Sea level data arrive a day or more after the satellite passes, and the field is a mapped estimate with a feature scale of about 50 to 100 km.
Gannet View shows conditions. It does not tell you where fish are.