SSS (Blended)
How salty the surface is, blended from satellites, floats and ships into a complete daily map with no gaps. It runs six to seven days behind — our slowest layer — so read it for big fronts, not today's plume.
Updates daily
More detail
Open ocean runs around 35. Lower means fresher water, from river outflow or heavy rain, and higher means saltier. The layer is made by the Copernicus Marine Service, the European Union's ocean data service, which blends satellite, float and ship measurements into one map.
It shows big features only. The method fills every spot, including where nothing was measured nearby. Measurements are blended over a radius of about 270 nautical miles, so it cannot show a river plume. Within about 108 nautical miles (200 km) of land the provider adds values from a long-term average to the real measurements, so part of what is drawn there is not this week's water. Use it for the broad pattern of where fresher and saltier water meet offshore. The layer covers the Gulf of America, the East Coast and Baja.
How it relates to the other salinity layers. SSS (SMAP) is the satellite measurement on its own: fresher, with nothing filled in, but with gaps where the satellite did not pass. Use SSS (SMAP) for the fresher, measured picture offshore, and SSS (Blended) for a complete picture of the broad pattern. SSS (SMAP) is unreliable within about 50 nautical miles of land. Sea Surface Salinity, from HYCOM (U.S. Navy model), is a forecast, not a measurement, and Salinity at Depth is the same forecast below the surface. The salinity layers share one color scale, 33 to 37.
The numbers
| How often it updates | Once a day, one frame per day |
| How fresh it usually is | Six to seven days behind |
| How detailed it is | About 8 nautical miles per cell, but measurements are blended over about 270 nautical miles |
| Where it covers | Gulf of America, East Coast and Baja |
| How far back you can look | 8 days back |
| Goes blank under cloud? | Never |
| Observed or modeled | A blend of measurements, with a long-term average added within about 108 nautical miles of land |
| What you see on screen | PSU, the standard salinity unit. Surface only |
| Published accuracy | The producer reports a typical error of about 0.33 offshore and 0.59 overall |
Source: a satellite picture from Copernicus blended salinity observations: satellites, floats and ships.