Currents (DUACS)
How fast the surface current runs, from the satellite-measured slope of the sea surface. No wind push and no tide, so it reads smoother and slower than the forecast current layer.
Updates daily
More detail
The colors run from dark purple for still water through blue, green and yellow to dark red for the fastest. It is worked out once a day from satellite measurements of the height of the sea surface, and the newest picture is about a day old. The Copernicus Marine Service, the European Union's ocean data service, makes it with a system called DUACS. It has no cloud gaps, and a blank spot is land.
The smallest real feature is about 95 nautical miles across: the Loop Current and the big eddies, not a rip or a tide line. The layer covers the Gulf of America, the East Coast and Baja.
It shows speed only. For direction, turn on the Currents button on the bottom bar: with the Observed tab chosen in Data Layers, its moving arrows or streaks follow this same measured current.
The color scale runs from still water to about 3.4 knots. On the website the crosshair readout gives the speed in knots when your distance unit is nautical miles.
A number can change within the week: the provider publishes each day's map again three and six days later.
How it relates to the other current layers. Currents and Currents at Depth, on the Forecast tab, are the HYCOM (U.S. Navy model) forecast, with wind and tide and finer detail, up to 7 days ahead. Currents (GlobCurrent) is also worked out from satellite measurements, with a wind-driven push added, but its cells are coarser and it is less reliable close to the coast. Use Currents (DUACS) for the big flow from the slope of the sea surface alone, Currents (GlobCurrent) to see the same flow with the wind's push added, and the forecast Currents layer for the shelf break, the tide and anything close to shore. All of them share one color scale.
The numbers
| How often it updates | Once a day, one frame per day |
| How fresh it usually is | About 1 day; a value settles after about 6 days |
| How detailed it is | About 8 nautical miles per cell, but the smallest real feature is about 95 nautical miles across |
| Where it covers | Gulf of America, East Coast and Baja |
| How far back you can look | 8 days back |
| Goes blank under cloud? | No. Blank means land |
| Observed or modeled | Worked out from the satellites' measurement of sea surface height, without wind push, tide or short-lived motion |
| What you see on screen | Speed only. Surface only |
Source: a satellite picture from DUACS satellite altimetry (Copernicus).