Each image provided on these web pages is, in fact, based on altimeter data straddling the epoch mentioned in the top right corner. Generally about eight days worth of data before and eights after the epoch is used to make one image for a certain day. That is mainly why the most recent image that can be computed is at least a week old.
Below is an example of the map of current velocities of the Gulf Stream in the vicinity of the East coast of North America.
This is the situation on 5 September 2005. The Gulf Stream main current is following the coast until it separates near Cape Hatteras. Just north of the Gulf Stream you can see a small warm-core eddy. This clockwise rotating eddy traps warm water from the south of the current (Sargasso Sea). South of the main current you see a huge counter-clockwise rotating eddy. This cold-core eddy has trapped a huge chunk of cold water from the Labrador Sea. You can also see how a meander is forming in the main current. Later this meander closes and sheds of another cold-core eddy like the one west of it.
The velocities of the currents are represented by colours as well as by arrows. Brighter colours indicate higher velocities. As the colour bar on the bottom shows, velocities are in the range of 0.1 to 1.0 m/s (meters per second), which corresponds roughly to 0.2 to 2.0 knots (nautical miles per hour). The size of the arrows also refer to the magnitude of the velocity, an arrow of 1 m/s (approx. 2 knots) is drawn in the lower right corner, next to the colour bar. The directions in which the arrows point is the direction of the current. Thus, an arrow pointing to the right indicates an eastward flow.
|DEOS | Gulf Stream velocities | Animations | Related links | Monitoring El Niño||