Dissolved Oxygen (O₂)

More detail

Set the depth first. Surface oxygen is near saturation almost everywhere, so the surface map is flat. Set the depth in Layer Settings to 656 feet (200 meters) or more before you read anything into it. It reaches from the surface to about 2,960 feet.

The app shows oxygen in mmol/m3. Where low-oxygen water comes up shallow, the water billfish and bigeye can use is squeezed toward the surface.

The model is Copernicus Marine's, and RipIQ puts it on the map. The model does not take in oxygen measurements as it runs. Each value covers a square about 15 nautical miles across, so use it for the broad pattern.

Its limits. The provider says its model puts the low-oxygen layer about 230 feet too deep and a little too oxygen-rich, so the layer shows less of a squeeze than there really is. The last couple of weeks are re-run daily, so a recent value can change. The time slider reaches up to 7 days ahead as a forecast. The layer covers the Gulf of America, the East Coast and Baja.

How it relates to the other layers. It comes from the same Copernicus Marine model as Chlorophyll Concentration and Phytoplankton Carbon.

The numbers

How often it updates	Once a day, one frame per day
How fresh it usually is	Same day the provider publishes it
How detailed it is	About 15 nautical miles per grid cell; from the surface to about 2,960 feet
Where it covers	Gulf of America, East Coast and Baja. Outside the regions the map shows the chart alone; the layers stop at the region's edge.
How far back you can look	8 days back
How far forward you can look	Up to 7 days ahead, as a forecast
Observed or modeled	Modeled. It never goes blank for cloud
What you see on screen	mmol/m3
Known bias	The low-oxygen layer is drawn about 230 feet too deep, and slightly too oxygen-rich

Source: the Copernicus model.